AC High and Low Pressures help

I have a 2000 996 and need to know what pressures I need for the Low and High side to get a good temperature @95 degrees outside temp.

Quotes source post: 6740044

High pressure in cold circuit function of ambient temperature. High pressure varies from a low of say 6 bar to 12 bar to a high of between 22 and 25 bar with ambient temperature ranging from 15C to 40C. Low pressure in cold circuit a function of ambient temperature. Low pressure varis from a low of 1.4 bar to 1.7 bar with an ambient temperature ranging from 15C to 40C. Sincerely, Macster.

Thanks I'll check for those pressures today when I test.

Quotes source post: 6740700

Regardless of pressure you A/C efficiency can be improved dramatically by simply bypassing the reheat/remix aspect of the system. Cool the interior down initially using fresh incoming airflow and then switch to recirculate airflow. Turn the temperature setpoint to its lowest setting and manually adjust the blower speed to attain, maintain, your comfort level. Even more efficiency and without bothering with the above procedure if you drop by Home Depot and buy/install a water flow shutoff valve to block HOT coolant flow to the heater core during the summer when you have no need for heating. My '01 C4 also has a switch in the compressor clutch circuit so I can TOTALLY disable the A/C in the wintertime. Be sure and check that the windshield defrost/demist/defog airflow ducts are closed and remain closed, I do this by turning the windshiedl airflow on (NOT DEFROST mode) and then off. The Porsche climate control will often start routing some of the cooled airflow to the interior windshield surface. This is not only a WASTE of cooling capability it can develop into a dangerous situation as condensation will sometime quickly form on the windshield exterior surface as a result of it being cooled. Pretty obvious what's happening in the daytime but in the early evening or at night.....

I had to top-off my refrigerant a few weeks ago. Took about 3/4 of a can to get it back up to specs. Now it's quite cold.

Quotes source post: 6740796

Most of the time when I need AC (or heat) I just set temp to 72F and select auto and think nothing more about it. I liked auto AC so much it was on my list of must have options when I went out searching for replacement for my Cayman. Said Cayman didn't have auto A/C and I didn't realize how much I liked it until I didn't have it. Times car/cabin really hot I'll lower windows and drive a few moments to vent real hot air out of car but then turn on AC and select recirculate. This uses air already cooled by AC (air in cabin) to decrease load on AC and thus cool cabin faster. I'm not about to install some manual heater control to turn off coolant flow through heater core. My experience is if one selects "low" temp little if any air flow routed through heater core anyway. Besides no coolant flowing through heater core can increase rate of corrosion in heater core and a leaking heater core can result. This was common back in the "old" days when coolant flow through heater core controlled by valve lever on dash. For a large portion of the year of course heater turned off thus no coolant would flow through heater core and heater core leaks quite common. I've driven my 02 Boxster in all kinds of weather from searing heat (116F) in desert to near zero winter cold from high humidty southern areas to dry dry high deserts in west and never had a problem with A/C heater system and any window fogging. Sure, in some conditions I turn off A/C before reaching my destination to give A/C heat exchanger time to dry windows can fog up but I've never had them fog up any other time with system on. Oh, every once in a while -- every month? -- I do manually select all the various air vent choices in manual mode to fully open/close the various vent flaps and run the temperature selection up to high and down to low to exercise the heater flap/diverter flap to keep these working smoothly. Sincerely, Macster.

Modern day automatic climate control systems mostly use air temperature sensing to regulate your comfort level. That doesn't always work because your body is sensitive to other environmental parameters for which you are the best "sensor". Radiant heating(/cooling) being the most obvious.

Quotes source post: 6740983

and UV sensors along with cabin and outside air temperature sensor. All I know is I can set A/C to 72F and put on auto control and leave Livermore CA on a moderately warm day and drive over the next 7 days or so 4000 or more miles through the CA central valley, over several mountain passes, through low and high desert, and through the the midwest in bright sunshine, darkest night, strong hot or cold winds, dusty conditions, the ocassional t-storm and even a snow flurry (or worse) and never have to touch AC controls because I'm unconfortable or windows fogging up, etc. Sincerely, Macster.

Quotes source post: 6741591

I agree with you 100%

I'm really depressed and angry mostly from the heat . I just got back from my friends and his gauge was the old R12 type and screws on and we did not have the adapter but I did have the qwik fill gauge from (checker) which just reads the low side in psi and temp, the highest I ever got was around 35psi at idle and 50 at 2000rpm and it did not blow even cool with one can put in. Curious but at 40 psi my car is supposed to get to around 40-60 degrees which the gauge shows in the vent was 105 plus? I think I have a leak and with a black car in 115 degree temp does not cut it. Has anyone tried dye to test for leaks or is this best left for the pro's.

In 115 degree temps.... let the pros do it!

Either that or just drive it in winter.

Quotes source post: 6741665

If refrigerant leaked out you have several problems. How did stuff get out? Where is leak, or leaks. If refrig. got out atmosphere could have gotten in. This means moisture. Dryer can handle some but if too much water in system freezes and blocks flow of refrig. Result? No cooling. System must be made pressure tight. System must be evacuated. 30 minutes at a very high vacuum to remove all old refrigerant, some oil, and of course moisture. New refrigerant of the proper type and amount then put into system along with oil and harmless dye (reacts to UV light I think). System charged up and run and leaks tested for and other things checked. If system has auto climate control this can be queried with proper Porsche test equipment and whatever problems are indicated can be fixed. Sincerely, Macster.

I used my durametric for fault codes and I did have some but the one that concerned me was the intermix valve error which I assume is the temp up/down button but it does regulate from hot to less hot at the moment when I move the temp button. I had my engine changed a while back and he vaccumed and they tested for leaks (said no leaks) and then I later installed the refridgerent but evidentally leaked out over time. I checked the compressor connections with soapy water but did not see leaks and figured I would start there. My concern today was to find out if I had put to much refg in causing the switch to shut off the system and blow warm but did not have a gauge to test for that. I do not know how much moisture it takes to mess up the system but here in phoenix 15% humidity it is pretty dry.

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Drier or more accurately I guess receiver-dehydrator (but I'm using drier cause it is easier to type) accumulates moisture if exposed to air. It is a desiccant which attracts moisture until it is saturated. So air where you are may only have 15% humidity but over time. Sort of like leaving a saltine cracker out on kitchen counter. Cracker just gets more stale from exposure to air and moisture in air. Well, if a recharge of refrig. leaked out system has leaks. This needs to be addressed first. Then system evacuated and then refilled with proper amount of refrig. and compressor lube oil. If drier/desiccant compromised by too much exposure to air it will have to be replaced. In some systems receiver/drier has a fusible safety plug which releases pressure if when refrig. temp goes too high, generally 212F. I'd not run system too much cause if refrig. not circulating oil not either and this can burn up compressor. Moisture in system will freeze at point where refrig. comes out of restrictor or expansion value and wants to expand. As it expands it cools and this cooling of course freezes any water in system into ice which can interfere with even block further flow of refrig. through restrictor. Not sure if Porsche has it -- have not needed to familiarize myself with system -- but some AC systems have sight glass on high pressure line that one can look through and see refrigerant flowing. If any bubbles this indicates charge low. Another thing to consider is flap that directs air flow through evaporator may not be working right and the system may be generating cold but no air routed through evaporator no cold air. In fact hot air cause some air likely going through heater core path. Hate to have you run system in case refrig. not flowing cause of risk to pump, but did you check to see if lines from expansion valve and into evaporator and evaporator cold? If no air flowing through evaporator temp sensor on evaporator used to detect this and system may shut of compressor to keep from icing up evaporator. In auto climate control system and I think even the manual AC systems at least with Porsche when outside temp drops below freezing compressor shut off cause moisture removed from air will freeze on evaporator and ice it up. No air will flow and icing may cause evaporator to crack from ice pressure. I'm no AC system expert. There are I'm sure a series of steps to follow to eliminate possible causes of problems that if followed could help you identify and rectify problems and get system running ok again. One thing you want to be careful about is in attempting to diagnose a problem you don't create a bigger problem, say by running system when you shouldn't and perhaps burning up compressor. You need an A/C expert. Sincerely, Macster.

Pros - price point sucks, but you save your own time and they will look at it again if you have problems. A good a/c shop will cover a lot of diagnostic bases for you while the car is in for the recharge. Gone are they days of dumping a can of R-12 into your 'Cuda lo-side before a Saturday nite date

Thanks Macster, all good points and as a note: I did notice when I put the freon in that the line did not get cold when it usually does. I did forget that I can check certain parameters through the climate control system itself and may check what my readings are at present today. Here is a list and how to. ------------------------------------------------------- First, press and hold the Recirculating Button, then press both Temperature Buttons (+ -). To enter the Diagnostics, you hold down the Recirculating and Air Up buttons simultaneously for 5 sec. The + - will then scroll up/down through a list of 'C' codes. Pressing the Center Vent Button will alternate between the 'C' code with it's actual value. To exit and return to normal operation, press the Auto Button. Here is a list of the available codes: 0c - ERL 1c - Oil Temp 2c - Inside Temp - From the Sensor mounted in the Aspirator Assembly at the side of the Dash 3c - Outside Temp - From the Sensor inside the Air Inlet of the A/C Unit 4c - Outside Temp - From the Sensor in Front Grill of the Radiator. Data is fed to the Climatronic from the Instrument Cluster. When not moving, the Instrument Cluster OBC Temp Display retains it's last setting until moving. This is to prevent heat emanating from the Radiator affecting the Temp Sensor. The Climatronic uses the lower of the two values in determining Fresh-Air Temp. 5c - Outside Temp - matches OBC outside temp display 6c - Coolant Temp 7c - Footwell Discharge Temp 8c - Sun Sensor (dash top) 9c - Sun Sensor 10c- Passenger Compartment Fan Speed 11c- Passenger Compartment Fan Voltage 12c- Temperature Mix Flap Command (1=COLD, 100= HOT) 13c- Temperature Mix Flap Position 14c - Central Flap Command 15c - Central Flap Position 16c - Footwell/Defrost Flap Command 17c - Footwell/Defrost Flap Position 18c - Recirculation Valve Command (1=OFF, 100=RECIRC) 19c - Recirculation Valve Position (feedback) 20c - Vehicle Speed in kph, updates once per second. This is True Speed, not the Speed+Safety Margin displayed by the Speedometer. 21c - Engine RPM in hundreds, also updates once per second 22c - ? 23c - ? 24c - Sun Sensor, Exterior Lights Switch, and Panel Lights control (term. 58 & 58d voltage) - used for A/C Panel Display Illumination 25c - ? 26c - ? 27c - ? 28c - Fan Speed 29c - ? 30c - Engine Run Time in seconds (255max.) (=0Xff) 31c - Timing Counter 32c - Displays Test 33c - Software Version (usually 3.4) 34c - ? 35c - Outside Temp from Inlet Sensor (filtered) 36c - Temp

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Most of the pros's can diagnose pretty fast and lead me in the right direction or repair if resonable. My only pet peeve is that if it is a leaky evaporator the whole dash needs to come out from my understanding and after all these years there is not a better design to eliminate this type of time\labor\cost intensive repair.

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And I'm certainly no expert either, by no means an expert... Certified shade tree mechanic, maybe....

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"...and UV sensors.." I suspect you mean IR sensors and those are there as part of the alarm system and I suspect not a part of the HVAC.

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One of the sensors listed in the AC section of the manual refers to a solar intensity sensor that outputs watts per square meter. Sincerely, Macster.

Quotes source post: 6740956

The instances of exterior windshield fogging seem to be even more rare. But apparently often enough that VW (larger installed base) issued a fix for their "Cayenne" whereas Porsche still states: "its designed that way". The Porsche HVAC system will route a portion of the CHILLED airflow toward the interior surface of the windshield once the cabin temperature approaches or reaches your temperature setpoint. Lowering the efficiency of the system via this method is quite bad enough IMMHO but if you happen to encounter an area of high humidity. My own instance, ONLY instance, was in the late evening on a HOT summer evening in Alabama. As we drove through an area that a rainstorm had just swept through the view through the windshield kept getting dimmer and dimmer.

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Typically mounted at the foot of the windshield, some with two, "looking" left (driver influence) and right. Yes, and from there its up to the programmer to decide just what to do with that solar radiation sensor signal. I have seen these systems with dual front clmate control that change the outflow temperature to rapidly/quickly and by large measure as you drive down a curving mountain road. These systems should only react to changing solar radiation sensing in the LONG term. What is more desireable IMMHO is a global "surround" view, radiant heating/cooling measurement mounted somewhere central within the cabin. Measure interior and exterior radiant "surround" aspects.

All of that stuff and they did not even put in a crotch cooler vent!