Is there any point in my trying to DIY AC not blowing cold?

I've had the card about 1.5 years. The AC blew meh cold in the spring of last year but it was pretty useless during the summer. Now that we're coming back into summer I really want some cold AC. But before I go down a rabbit hole of checking, pressures and ambient air, and from what I've read on other posts, not a lot of conclusive results that those bring, wanted to know if it's worth the time. I do have the black foam in vents issue so I'm almost positive the blend doors are shot. Is there any harm in trying to just add a can of refrigerant and see what happens? I can hear my AC condenser turn on. I've cleaned out all the gunk from my bumper radiators. The cap from the low-side (refill port) is missing, so I wonder if any refrigerant has been leaking from there. I don't have a gauge for the high-side, just a low-side gauge and can puncture adapter. So before I start buying stuff, want to know if it's worth it. Most posts end in "go see an AC mechanic".

If it were me I would sacrifice a can or two of refrigerant to see what happens . And get a cap on that fitting . Schrader valves can leak the cap is a secondary protection . Whatever you do please don't add stop leak goop to the system . If you have a leak fix it right .

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First thing to do is see how much, if any, Freon is still in the system. Put your low side gauge on, see how much psi is there with engine off . Depending on your region/ambient�, should have somewhere around 70 psi on gauge this time of year if you haven't leaked it all out. If there is pressure in system then try the next step. Start engine. Make sure compressor is running, ac set to hi fan and lowest temp setting. see what psi is at idle, if you have over 25 psi, bring rpm up to 2500 and recheck low side psi. Report back what you find.

Just watch a few youtube videos on how to fill your system, sounds like you have a slow leak. If it lasts 3 months, then you will have to find the location of the leak and fix it, or have somebody fix it for you. At that point you completely evacuate the system and charge the proper amount. I would get one of the "AC Pro's" bottles, somebody I know just bought one and it even bluetooths to your phone and gives you a lot more info for people who have not done this before. I don't think it's more than $50. Best of luck.

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Well off to good start... I hooked up low side gauge, and didn't have the valve on other end fully close, so vented the system right from the start (this is why we wear protective equipment!) I yanked it right now, but now after closing it the gauge reads 15psi. I don't know how much I vented, or how fast it loses pressure, so I can't say now what it was to start. I then started car, ran at idle and rev'd to 2500 and the gauge never moved (video recorded it). When turning on AC, the engine drags so I know the compressor is kicking in. And both radiators are blowing in front when AC is on. So, 15 is obviously low, but how fast it lose pressure I can't tell you. Does the lack of it changing PSI mean anything? It's chilly out here today, under 60F.

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Yeh, I saw those, but figured a dedicated gauge, and a can from AZ, would be cheaper, and I just like analogue over digital.

AC is not something you really want to mess with. After 20 plus years (my car 7/98 so still on factory fill), last summer my AC was cool but not cold. I contemplated the same thing...just get a can of refrigerant from the auto parts store and put it in...but then I read up on it some more and decided to book an appointment for an AC professional with the proper equipment. He was well versed in British/American/Porsche cars. He hooked it up to his machine, evacuated the system, then filled it with nitrogen and pressure tested it for 30 minutes. No leaks. While it was still hooked up, he filled with proper amount of refrigerant AND oil for the compressor. Also added a very small amount of UV dye so in the future, if a leak occurs it will be simple to find. The AC blows freezing cold air now. And, all my foam blew out the vents 15 years ago and I never did anything about it except clean it up. Finally stopped. All in for the AC professional...$133. It was well worth it. Best thing was I got to spend a little over an hour looking at all the cool cars he had in the shop, from old MG's to Ferrari's to some exotics. I also was able to bend his ear over all kinds of stuff during that time. I do all of my own DIY work on the car, but AC is best left to a knowledgeable professional. https://rennlist.com/forums/996-foru...-recharge.html

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Yeh, that's kinda exactly what I'm thinking. If these initial tests yield inconclusive results, just gotta find the right indy, who wants to do a quick job. Everyone is so focused on big service work now with their bookings backing up. "No I don't need a new clutch with my AC refill"

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Well, at 15psi on cold car at 60�ambient, you've got a leak for sure, maybe not a massive leak or it would be at 0. But a considerable one never the less. Reason psi doesn't change when engine running, is the low pressure switch won't engage the compressor clutch @ 15psi. Couple of options. 1)Bring it to a pro and pay. 2)Or since you do still have some pressure in the system, try dumping in a can of r134a with leak detector dye in the can. And 1 can of 134 with oil charge would also be nice. Finish your charge with the oil/freon can. iirr it takes around 2lbs 134. Charge slowly with all windows open, ac on hi fan and set to lowest temp, on a warmer day if possible. Charge slow, being so low on freon the clutch will kick out from low pressure switch till you get the charge up in operating range. You'll hear it and see on the gauges when the compressor kicks in, keep dumping in freon till it kicks in. Finish Charge till a thermometer in the dash vents reads mid 40�. Run it and see how long the charge lasts for. Once it leaks out you should be able to see the leaked dye at the point of the leak. Might be surprised, could last for many months, or not. Once you find the leak you can do it right. Fix the leak, might only be a o-ring, or could be the compressor seal, evaporator coils, condenser coils, x-valve, or piping. The dye should eventually tell you exactly what is leaking... Once the leak is fixed, change out the drier, see if you can borrow/rent a vac pump and gauges. Some auto parts stores loan/rent vac pumps & gauges out. . Vac it down for at least an hour to remove any moisture, shut off gauges tight and make sure all hose connections are very tight. Leave system in a vac and make sure it holds vacuum. Then re-charge it the same way with correct amount of 134.

Do not EVER put A/C leak sealer in this car, or any car for that matter. The easiest way to get an estimate in if the A/C is charged is to do this: (works best when it's hot out) Run engine. Doors open. A/C on MAX cold, fresh air (not recirculate) Blower on MAX Rev it up to 1500 or 1800 for a minute or two Feel suction pipe into compressor. This is the larger of the 2 pipes. It should be cold. If so refrigerant level is probably OK.

So I tried to refill today. I ran the engine with the AC on max. Hooked up the gauge with the 12oz can of 134. Slowly released the valve and let the system refill. However, it went from 15 psi to 40 psi in a few minutes, but the can of 134 still feels very full. And the AC still doesn't blow cold. I do hear the engine drop when the AC is turned on. Any ideas? (I forgot to check the pipe into the compressor to see if it felt cold or not)

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What is the idle low side pressure, what is 2500rpm low side pressure..? What is ambient temp there..?

If the gauge is only showing low side pressure you will be completely in the dark. That said, the variable compressor and thermal expansion valve setup on these cars will (should) keep the low side pressure around 40 PSI unless the system is completely empty. Since you saw 15 PSI when staring I would assume the system was almost completely empty. Hate to say it but you should use a sniffer to find the leak and fix it. I would suspect the condenser(s). Look for oily spots on the condenser fins. General rules for R134a A/C systems using a thermal expansion valve and variable compressor: low side should be about 40 PSI, high side should be ambient temperature multiplied by 2 or 3. The pressures don't tell the state of charge on this type of system - really need to either start empty and add the correct weight of refrigerant or use the temperature of the compressor suction to see how full it is.

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Ok I should probably not be doing this as I'm still not clear what is to be expected in terms of pressures, and have read so far that it's not really a good indication of a working system. Pulled car into sun. 75F outside. Connected gauge and 134 can in OFF. Turned on car, brought it up a little bit in temp at 1500rpm (hate idling the car). Pressure on gauge was at 30ish pis. Turned on AC full blast heard the Engine engage. Went and opened valve and let 134 slowly flow. It held the 30psi mark. Continued to allow it to flow and rev'd engine and recorded gauge but didn't see it do much. Got almost all the 134 in and did start to feel the AC get cold. Switched off car, but then the gauge started to go into the red up to 80. Freaked out cause I realize i have no idea what this all means. Now i am at a total loss of what to do. Have I over filled the system? Why does it sky rocket after the car is turned off? On compressor side, small tube is hot, large tube is cool (as in not hot) but not cold.

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Idle was 30. Revving it maybe got to 35? Ambient is 75F (I pulled car out of garage into sun). See notes above as well. If you're filling from a can, How do you know when to STOP? This is what I don't understand... Looking a chart online, 75F should equal 40-45 psi (but I just want to confirm that). And make sure that when car is off, the 80 psi I was seeing is not some danger zone....

I know this may be a longshot, have you checked your front fans and resistor packs on them? If bad the ac won’t work. I found this out a few summers back on 05 degree day.

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I have cleaned out the front radiators (bumper off) and confirmed they blow, but haven't checked the resistor packs (i have to admit, not ever sure what those are). The AC did start to get cold as it got closer to the end of the first can, so I suspect freon is part of the issue, but I am really going blind here. Initially reading online, it seemed so straight forward to recharge system... turns out there's math involved!

If you have durametric you can turn them on and off. Other test is turn on ac. Go to front of car and see if the fans are sucking air. If the fans are our There is a diy for the resistor packs or you can buy the whole fan assembly.

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Don't worry, there is a hi&low pressure switch that will shut things down if needed. Lowside line should be cold when fully charged. theprf is correct, that charging a maybe leaking, unknown current charge state without full view of hi&low side pressure is less than ideal. But can be done successfully to get you in the ballpark.. I'm hoping maybe we can get your ac into the ballpark of operating temps. What now is the center vent temp when driving at 2500rpm or so...? You can get small digital thermometers cheap of Amazon. Amazon Amazon If you have a substantial leak, theprf is also correct in that a professional would do a leak check when he finds a system low on refrigerant. It is the right thing to do as a professional will have all the equipment needed to do this. On the other hand, we are a diy project here, and have no idea how long its taken the freon to leak out. In a car system, eventually(maybe many many years/decades) freon will seep out past comp seal, orings, etc, without a substantial leak. For the diy a can of freon is cheap way to see how long a charge lasts and give one an idea if they do need to go for a leak search. If you do find a substantial leak, and don't have a quality leak detector,,, You can also use a Freon with LEAK DYE to help pinpoint a leak without a freon leak detector. Don't mistake leak dye for a freon with leak stop , 2 very different things. Never use leak stop in any ac. Take my 996.1 car. When I got it a few years ago with 31,000 miles the ac wasn't blowing cold. Put my gauges on, it was low, under 20psi low side at idle. Dumped not even a full can in and got it to where I liked the pressures and was blowing 45� out of the center vent. Just got in car today low 80's ambient temp here. I keep a digital thermometer in my center vent, it still read 47� after short ride, 3 years after I charged it up. Did notice when I pulled off the gauge hose a slight leak in the low side schrader service port. I always put some soap suds leak detector on service ports after I pull gauges as they seem to be a common slow leak/seep area in all types of ac. Tightened the service port cap down tight, and will have to deal with that eventually, but its been 3 years is my point... To answer your question... "Switched off car, but then the gauge started to go into the red up to 80. Freaked out cause I realize i have no idea what this all means." Normal, don't worry. As soon as the compressor stops hi & low sides pressure will start to equalize till they meet. Freon is an organic gas, pressure is temperature. A jug of freon normalized in a 70� room will have the same pressure always at that temperature regardless of how much freon is in the jug, 1lb or 25lbs, doesn't matter, temperature is pressure. Same jug of freon in a truck bed in the sun on a 90� day will have a very much higher pressure.

What allcool said. You were probably about empty on refrigerant. I don't have the manual handy, but I would bet it takes about 1.8 to 2.2 pounds of refrigerant to fill the system. How much does a can hold, should say on the can. I haven't bought cans in years I buy the stuff by the 30 pound jug... I would think you need quite a bit more refrigerant. The amount of refrigerant needed should be on a sticker somewhere near the fill ports. When to stop filling? Without a high side gauge it's a bit of a guess. The best way to tell is what I mentioned earlier: A/C on max low, fan on high, doors open to put the highest load possible on the A/C. Then add refrigerant a little at a time until the suction pipe at the compressor is cold. When it's cold to the touch and water is condensing on it that's the minimum amount of refrigerant. Add a tiny bit more and call it done. Do check the fans although I doubt that is the problem. Just turn on the A/C and feel for air exiting under each front fender in front of the wheel. The fans should run on low speed as soon as the A/C is switched on, even if there is no refrigerant in the system at all. Edited to add, if there is a persistent leak and the system is repeatedly refilled eventually there won't be enough oil in the system. This is because when refrigerant leaks out some oil leaks out too. Eventually there is not enough oil to lube the compressor and it seizes up. This is a super common problem on Chrysler cars from the 90's through 2015 or so as the evaporators always leak, and it's a really big job to change the evaporator, so people just keep refilling the A/C until the compressor self destructs.

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Thank you both for taking time to reply. I did some more reading up online and saw the low side reading high pressure was normal after system turned off. I will try again tomorrow and see if the compressor pipe gets actually "cold". I found a layman's 134a chart online and 75F ambient should equate to 40-45 PSI low side. I'll try not to stress when turning OFF the car and watching gauge climb. Both radiator fans kick on and blow no problem. As mentioned, I did feel the "coldest" air in there since I bought the car 17 months ago after that partial can. So fingers crossed it really has just leaked out. I can't make it through another summer with no AC (cab or not!). Car came with 99k miles and I've put 3k on. Just replaced water pump,thermo this past weekend, and judging by that the freon may never have been serviced in who knows how long.

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My 99 goes from 675 RPM to 800 RPM when I press the AC button. It doesn�t drop.

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Yes typo.

Further update. I bought another can of 134 with UV dye. Brought car out into 75F sun. Ran it with 134 and gauge connected. At cold and off it was at 80psi. I turned on full AC and it dropped to 38PSI. I opened the valve and let the freon flow in while revving engine around 2k. Put a thermometer in the vents: 70F (it was 80F ambient in the car). When I revved engine, thermo pen temp would raise to 76F. Here's the odd part now. Gauge is sticking to 38psi, valve is open, can is cold, so freon moving, but going very slow. I suddenly hear the pasenger side radiator fan kick on high. Realizing it was running at all. Drive side is running constantly. (they did indeed run before because i tested them a few months back, but something may have changed, I did just change the water/pump coolant). When passenger side radiator kicks on on high, the pressure on the low side drops to 25psi. Fan then turns off and psi rises back up. This happened on and off with car is at operating temp with needle straight up. Is there something wrong with my fans? They obviously work, but I thought it should have been on all the time when AC on. Also I remember them kicking on when I got home and idled, and now they come on for a brief moment. Even when coolant temp got to 208F (turned car off at that point). Temp on thermopen did get to 60F. Probably the lowest it's been since I've owned it. I felt the rubber pipes in engine bay. One is very hot, the other is just normal temp. I removed the 134 as I just get nervous. It still feels very full.

The radiator fans should run on low speed as soon as the A/C is turned on. When the high side pressure exceeds some value, probably around 180-220 PSI the fan shifts to high speed. That is pretty normal with the car not moving and the A/C under high load. But, both fans should come on the same speed so if the driver's fan was not on high then something is up with the fans. Do check they both work. There is a pressure switch mounted next to the filler ports in the cowl that does three things: #1. Disables the compressor (but not the radiator fans) if the A/C system is empty; #2. Disables the compressor (but not the radiator fans) if the high side pressure is too high (like 450-500 PSI); #3. Turns the fans on high speed when the high side pressure is moderately high, which forces more air over the condensers, which brings the pressure down, which switches the fans back to low speed, and the cycle repeats. At this point you really need to figure out the high side pressure. Also I suspect the blend door in your heater box is probably not sealing because the noise deadening foam is long gone so you are getting heat from the heater core mixing with the cold air from the A/C evaporator. That will never work properly, the heater is many times more powerful than the A/C. When you say the "rubber" pipes, those are the air conditioning pipes? The output from the compressor will always be very hot which is what it is supposed to be. With the other being "normal" you probably are close to the correct amount of refrigerant.

Something sounds strange in your charging set up...? Can you take a pic of the setup you're using to charge with..? Might be time for a cheapy Amazon set of gauges and vac pump. This is not an industrial quality every day professional use type tools, but more than sufficient for the diy guy, Amazon ac tools ac tools Look around on Amazon, lot of these type diy kits, make sure to get one good for cars 134 Then you can start from scratch and see hi&low pressure that will help troubleshoot the system. If you do need to change out a leaky component you'll need these.

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Yeh, i'm pretty lost at this point. I had read somewhere the blend doors didn't affect temp that much, but if they do, then this whole process is useless cause mine are likely very shot considering all the foam i've cleaned up over past year. Here's the gauge, also from Amazon. Didn't know at the time I needed high side too. Most general diy ac docs made it seem like just a can-o-134 solved all. And of course now I have to diagnosis both fans not turning on with AC and why high speed takes so long (if at all) to kick on. Sigh.

how many full cans have you put in the system..?

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probably a little over one? had some technical difficulties with thr first one. and second, even though it was on low for a while, still feels pretty full. im really nervous of over filling

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Our cars take iirr 32 oz r134a. I'd try dumping the rest of that can in and see if your vent temps go down. Not sure what you meant by technical difficulties, assume you're having trouble getting the freon in. Make sure on your set up to fully turn in the needle valve to puncture the can fully, then back it out all the way. Charge at 1500-2000 rpm. Our cars have a long pipe run from the low side service port- to the compressor, so you can dump some liquid in for a few seconds at a time (invert can briefly a few times) might help to get all the dye in and charge faster with a small can... The foam vent seal problem theprf explained is interesting, never thought of that. Without the compressor * on, but in hi fan/max cooling mode, does heat come out your vents, what temp do you get compared to ambeint..?

You really do need to fix the blend doors. When the foam's gone they are a piece of galvanized steel sheet that's about 30% holes. It's never going to be "cold" with that much hot air leaking in.

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So fully open the valve? I was reading it should only be done "slowly" but of course I don't know how slow or fast the valve lets the freon out. Per technical difficulties: Let's just say the EPA would not be impressed... and I'm glad I wore very heavy leather fire proof gloves while working with it.... I'll try to do the rest of the 12oz can with dye tomorrow. Any idea why when the passenger side fan kicks on (high) the low side pressure drops significatinly? And then goes back up when it turns off. Can't believe i gotta start trouble shooting the fans now. They used to kick on when I turned the car off, now they don't. Yes vents might be an issue. Heater works 100% blasts hot air. And I just replaced water pump and full coolant flush from green to pink (trying to solve why it only took 5 gallons of coolant too, fun times here in home diy garage).

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As long as your set up is connected correctly to can and service port with no leaks, you can't charge to fast with those little cans in a 996. Most of the time the problem with the small cans is you can't get it in fast enough or at all. Ok, after looking at your pic, not sure if you have the puncture type can that uses pointy needle type set up, and backing out the needle once can is punctured opens the can valve. or the self sealing can that can only use the flat nose needle that can only be used on the self sealing cans. Some of these self sealing epa can systems have funky valves that are fully open in the middle position, some in the full down position, iirr. I really don't like the new little can setups, but once understood they do work. Bottom line, figure what setup you have and when the can valve is fully open. then use it fully open. If you're having problems with the can/valve leaking and haven't figured out how to connect leak tight yet, don't use the freon leak dye cans as it will lightly stain anything it touches if its dripping down from a leaky can/valve/hose/etc.... Best to have a leak free charging setup before you use freon with leak dye in it... However, its a good idea for you to have some dye in there as we know you have a leak, just don't know where/how big it is and the dye will show that. Make sure to have the ac drain clear as the water/condensate that leaves puddles under you car will have dye in it if the evap is leaking... Keep at it, you'll get it. Hopefully its a very small leak that took a long time to leak down. Or not, and you easily see the dye and change out the leaky part. As for the vent door foam problem, wasn't asking you if your heater works. Was trying to figure a way to see how much hot air they were leaking in the cabin on full cooling mode. Hence me asking you to turn ac on max cool fan and lowest temp, then turn off the compressor * button on the control panel. Then measure vent temperature and compare it with outside ambient temps to see how much heat was being introduced by the missing foam seal. Let it run like this for a few minutes with doors windows open before noting temps. jmo....

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I'm not familiar with the vent doors on our 996, although have read about the foam problem. Seen many automotive vent doors, just not a 996. No idea of the condition of my 996.1 & 996.2 vent door foam seals as I've never had problems or foam blowing around. But my top is down most of the time so that might blow the foam out of my car before I see it..? But both cars ac works great with mid 40� vent temps when its hot out... So, if I understand you correctly, the vent doors have holes (30%of the doors surface area..?) all thru them like Swiss cheese and the foam covers these holes blocking air from passing thru the holes..? Any diagrams/pics of the doors we're taking about. What should i search for to see this..?

This is what the blend door looks like. The white showing through the holes is cardboard that I glued on to the opposite side. It's easy to see why the blend door does not do much once the foam is gone.

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Thanks for the pic, it explains everything. Is there a good test to see if the foam is gone.?

I suppose an endoscope would do the job. I think the temperature blend door can be easily seen from the access hole in the frunk used to change the heater core.

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I'm sure my blend doors are shot. But when it warms up later today plan to keep going with the can of freon. 1. I think the connection is tight, yeh don't want to be staining everything connecting the can. The gauge is a needle valve, god I just assumed the can was the same. Says is a "self-sealing can", though I'd dare not disconnect it considering the first time I connected it I froze my leather glove solid 2. Will connect it all, and turn on car. High AC (it's bugging me the front right fan isn't turning on with AC) 3. Open valve fully, rev engine to 1500ish and keep checking the PSI. 4. Cross fingers. 5. Measure vent temp with temp thermo-pen gauge. Have a infrared gun too. Questions: 1. Is it possible to over fill the compressor? is there a symptom to look out for? 2. Why would the low side pressure drop significantly when the fan speed goes from low ( don't forget low on passenger side is not running ) to HIGH? (both fans work on high) (NOTE found I have a missing relay which is why Fan 2 Low was not engaging. Popped in the high one to test, now both fans turn on low--- sheeeesh!) Also a tad concerned that the high fans only turn on for a few seconds, even though coolant temp (via OBD) were getting up to 210F. I DID just change coolant and put in a low-temp LN thermostat. And I had the engine bay open the entire time, and read the engine bay temp can be used to trigger fan speeds. So many questions!

Here is a good chart on what a healthy A/C system reading should be.

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I must have checked fans at high at some point and assumed they worked. I did find low speed was not working on one side - and now like an idiot, found I'm missing the relay entirely for that fan+speed. So that's one less thing to troubleshoot!

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If the system pressure get so high that it's dangerous the pressure switch will shut off the compressor. You don't want to let it get that high. Essentially if you are loading the A/C system up by running it with the doors open (or the top down, I don't have any convertibles so I never think of this) AND it's hot out, like 75F or higher, you want the radiator fans to be shifting from high speed to low speed constantly several times a minute. That's plenty enough refrigerant. When the fans shift to high speed there is much more air over the condensers, which cools off the refrigerant more, so the pressures go down. Then when the pressure goes down the fans shift back to low speed, the refrigerant gets hotter, the pressures increase, and the fans shift back to high speed. If you are in traffic on a hot day you should hear every car doing this. But seriously, you really ought to get a real refrigerant gauge set. High side pressure tells the story. Sometimes you can rent them from Autozone. You can get a nice set from Amazon for about $60. www.amazon.com/dp/B088RLQKR6

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Found this thread when checking your profile to see what 996 you drive as I replied to 'hot engine:..' Your valve and can are not compatible! I experienced it myself not knowing that self-sealing cans had appeared on the market and trying exactly what you did. Your only option is to replace the valve with one for self-sealing cans. The center pin in that kind of valve moves down onto the valve in the can and opens it and the r134a then flows around it into the hose. It must stay turned down for as long as the r134a is to flow. Once done, turn the **** in order to retreat the center pin and the can will be sealed again. After that you can safely unscrew the whole valve from the can.

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Huh, that might explain why it seems it's going to take forever, if ever. I did empty one can successfully, but who knows what I did there. The valve on the gauge I bough, has a needle that when turned all the way blocks the flow (in order to pierce the foil). But I guess I see your point, that if I turn it all the way OUT, then the can would seal itself. I just searched the answers section on the product in Amazon for "self" and low and behold the seller says "no" it doesn't work with self-sealing cans. Some reviews said it work, but... sigh. I don't usually return items to amazon that I legit used, but I am going to return this one. Thank you for the note!

[QUOTE=Ben8jam;19428924 The valve on the gauge I bough, has a needle that when turned all the way blocks the flow (in order to pierce the foil). But I guess I see your point, that if I turn it all the way OUT, then the can would seal itself. [/QUOTE] Like I said above, they both use a needle. But, The needles are different. The puncture cans have a pointy needle, the self seal cans use a flat nose needle. Look at the the end of the needle, if its sharp pointy, its for a puncture can. If it has a flat nose, its for self seal cans.

Update: I bought a gauge set, with correct self-sealing tap. And tried again. I had run the car and it was hot. It was also about 90-95 degrees F out and was working in the sun. Connected High and Low and let car idle with AC on full. This is what it equalized at: I connected the R134 to the tap, and after a LOT of annoyance, finally started to see the freon go in via the wet-portal. I used a can with Dye. It was impossible to tell when the freon was flowing as it seemed to go in spurts, and depended on the valve being more in or more out, so I think it went in fairly quickly. I forgot to take the after pic of course, but the Low was reading about 45 psi and the high 225-250 psi. This would be the second can now of 12 oz 134a. Some may have been lost in the process of filling. I checked the temp in the vents and it was only able to get it down to about 59F. Last time it was mid 40s, but it was also 20 degrees cooler ambient. Next I have PAG oil coming and will add a min of 4oz to be safe. YES I know I should do a vac down etc, but I'm just so busy with other things in life, these small half-victories are big for me. Only mishap is when I was turning the gauge cluster towards me, the high pressure line that connects into the gauge started to un-twist and sprayed yellow dye everywhere. I had tightened them down quite a lot too. I'm glad I was still wearing gloves. It's going to be interesting when i check the hood interior with a black light tonight

U should fill through the low pressure side.. If u full high pressure u have to turn the can upside down so it adds as.a liquid. Do not add any oil if u did not take any out (i.e. drained and clean the system) . Look ip charts for r134a as frein is a brand name and not what u r adding for the correct pressures.

Quotes source post: 19577904

Yes I added the freon via low pressure side. Per oil, a few commented above to add some oil as if there is a leak over past 25 years, oil probably went out with the freon. Is that not the case?

Couple things. See the scales on the blue low pressure dial? Look at the one that says R134a. The temperature under the needle on that scale is the coldest it will get. Typical low side pressures should be about 38 PSI. 45 psi low is too much, which means either (1) not enough refrigerant so not enough cooling capacity or (2) inability to cool enough due to excessive heat load or (3) something wrong with the txv. Now idling is hard on everything. No forced airflow through the condensers is big. With 90F ambient and high humidity I would expect minimum of 225-250 high side pressure at idle (rule of thumb is 2 � ambient temp + 50). So you may still be low on refrigerant. But first check high side at 3000 RPM. If over 300 PSI do not add any more refrigerant. The best way to check fill state is to see if the suction pipe at the compressor is cold. If so, system full. I still think the blend doors are allowing the heater to reheat the chilled air. Check this by setting the climate control to "low" and shutting off the A/C. The air out of the vents ought to be ambient temperature; if not the blend door is a problem. I would not add oil unless there has been a large oil loss or something has been replaced. Too much oil is way worse than too little. I have seen these Sanden compressors swallow an oil slug and have the housings literally explode. That's less likely on a 996 with the compressor the highest part of the system but still possible. Also the oil is useless for transferring heat while displacing quite a bit of refrigerant. If you insist on adding oil add no more than 1/2 ounce. The oil blowing out of the high side hose shows there is plenty of oil in the system.

I would not add oil unless y know there is none in there the dye is a lube too. Adding too much can lock up a compressor and cause pressure issues. Its really a hard call to know whats in the system.... the only way to know for sure is flush/clean the entire system and drain the compressor. Chances r very little came out with the refrigerant as it leaks as a vapor. The reality is the oil and the system has been charged for 20 years and it has only leaked for a very short time. Doenst take long for a system to empty, at that point the oil just sits in the lines and compressor .

Never open the high side to charge the system unless you have vacuumed the system and the engine is not running. Having the high side opened while the compressor is running can cause the can to explode while you're holding it. Doing so will give you some REALLY nice scars.

Quotes source post: 19578058

Yes never opening high side valve. No one is opening the high side. No high side was used in the charging of the system.

Quotes source post: 19577771

The reason we r talking about the high side is this comment above.... u should so nothing or ar almost nothing in the wet bulb when fulling from the low side as it should all be vapor. The wet bulb indicator is for high side filling and confused me when i read your post and i made an assumption. Now the hard work.....get your eyes in an the tight places where the pipe connections r to find the leak.

Quotes source post: 19578323

If you turn the can upside down, you get liquid. Isn't that pretty standard procedure? I think the can even says to flip and agitate while filling. I had mentioned the high side bc the adapter had unthreaded a bit where it connects to the gauge spraying a bit of liquid freon out. The valve on the gauge for the high side will and always will remain closed.

I dont really use the cans. I guess any way u can get it to fill from a small can works.... When using a large 30lb bottle u fill upright (vapor) through the low side. U can flip the bottle anf fill (liquid) through the high side. As said above u can nuke a bottle filling from that side so that should only be done with the proper machine. i would guess your issue with filling from the can is when u loose refrigerant the pressure in the system equalize and now u r using the compressor to pull the vapor in. When u use a machine or a vacuum pump the negative pressure pulls the vapor (or liquid) in. Also without pumping the system down moisture can remain and cause ice to form and block the expansion valve. I would suggest once u figure out and fix the source of the leak have a shop recover the refigerant, vac it down and fill it with the proper p-car amount.

Good job Ben8jam, you're getting there... Your first gauge pic looked like you were in the ballpark if that was at 2000rpm. .Now seems you are probably overcharged a little from what i can gather from the last few of your posts. But thats ok if ya got a leak. All the advice you've been getting on this thread is good... As the prf said, the 134blue out most temp/pressure scale on your gauges tells you at the 33psi it was at, the evaporation temp was 38�. Rule of thumb is, at full fan speed, air going across evap will be about 10� higher than evaporation temperature of the coil, so you were at 48�, very close to what you want). Now that relationship of pressure to air discharge temperature is only when txv/evap has enough freon in it to flood coil out completely. Assume at those pressures your suction line at compressor is cold signifying flooded evap,,, plenty of freon With the current charge, gauge psi you mention of 45low & 250psi hi, you have more than enough charge. Are condenser fans on hi speed and condensers/radiators clean..? Pressure is temperature, so at your current 45psi your evaporation temp is around 50� making discharge air around 60�. to high. Might want to see what gauge psi goes to at 2000-3000rpm...? Maybe slowly vent a little out till low side gets to 40psi..? Or take off gauges wait a day or 2 and see how much leaks out. You'll probably lose at least a few oz when removing gauges.... jmo

Update I retested with engine much cool, just off start up, sitting in sun at ambient 91-93F. High speed fans never kicked on, engine did not get to full operating temp. Engine off as well as Engine on at idle before turning on AC: 87 psi LOW // 90 psi HIGH Engine on at idle with AC on and gauges equalized: 30 psi LOW // 155 psi HIGH (engine cold) Revv'd engine a bit, then checked at idle with AC on: 34 psi LOW // 180 psi HIGH (engine getting warm) Engine off for about 10 minutes while waiting for daughter to come watch gauges. Engine back on, at idle again with AC on: 36 psi LOW // 195 psi HIGH (ambient temp gone up a couple degrees) Revv'ing engine at 2,000 rpm with AC on: 29 psi LOW // 205 psi HIGH Revv'ing engine at 3,000 rpm with AC on: 29 psi LOW // 210 psi HIGH So I'm not sure if the higher low side pressure I had at idle was because the engine was very hot (much hotter than today), of if I've lost a huge armount of freon between yesterday and today. I don't think that is the case, because the last time I put freon in was three months ago, and I would expect the system to be totally empty if it was leaking that fast -- but any thing is possible. Also, there's not way to push all the freon that is in the high and low tubes after checking pressure is there? I had to vent those tubes after I disconnected everything - heck of a lot of yellow liquid came out... Here is pic at 3000 rpm, engine still not all the way warmed up.

Im pretty sure u r still under filled. Here is a chart based on ambiant temp.

Probably a little underfilled. Did you see if the suction pipe to the compressor was cold? To minimize loss of refrigerant when disconnecting, there are 2 ways depending on how good your hose fittings are. If your hoses have got fittings with internal valves (I think they all do now) do this. Shut off the car. Let high side pressure equalize. Disconnect high side connection (pressure should stay in high side gauge). Start car & engage A/C. Crack high side valve on manifold. Crack low side valve in 5 second bursts until the pressures are equal which sucks the refrigerant in the lines and manifold back into the system. Close both valves. Disconnect low side valve with A/C on. If you have a really nice A/C manifold you may have screw down valve core depressors on the fittings. I always pop these off with the screw down still screwed down otherwise the schrader valve takes too long to close. If your hoses don't have internal valves turn off the car, wait for pressures to equalize, then disconnect both connectors.