A/C cold air fading to warmer

I have an A/C problem that apparently hasn't been reported before. Has anyone experienced the following? The A/C blows cold air initially, but the air gets less and less cold as I drive. It seems not as cold as it initially was after about 30 miles, and continues to go south from there. After 60 or so miles I'm still somewhat comfortable, but only because I have all vents directed at my torso. By 100 miles the cabin may be as warm as the ambient air outside. The air that the A/C blows never gets as warm as the outside air, so I prefer to have it blowing on me than the outside air, but I do have the fan near maximum by the time I've driven 100 miles. Hitting the recirculate button doesn't seem to help for long. The dealer said it tests fine after 5 miles. Of course, I agree with that. They advise to use recirculate all the time, but that doesn't do much good. The only A/C problem reports I've found here are low on refrigerant (3 cases), bad schrader valve, hose clogged, condensor gasket misaligned, and small leak in evaporator and condensor. But none of these cases were characterized as following the gradual loss of cold air over the miles form. Any Ideas for me to take to the dealer next week?

Time for dealer service. It is probably low coolant caused by ?

Tell the dealer to fix it. It's not your responsibility to diagnose the root cause of the problem, it's the dealers! The aircon should blow cold. Period. Don't let the dealer fob you off that it works okay for 5 miles. The problem you're having is the aircon doesn't work properly after 100 miles. It should work fine and blow cold air. Recirculating the air all the time is bad.

I have exactly this same problem. Playing with the settings--lowering temp, recirculate--helps for a bit, then the thing goes back to being just better than tepid.

Thanks. Next week I'll request some diagnostic work instead of just a short test drive (but I did tell them that it always starts out blowing cold air). I'll also give them my list of previously reported sources of A/C problems. I know he checked the air flow temperature last time because he left his thermometer sticking in the dash air vent, and his Snap-On screw driver in the trunk. rsgl: I'll post whatever they find; maybe your problem has the same source.

Jim, I also have the same problem. I found that if I move it to Max for a minute and then back, the air is cold again. I too had it checked at the dealer with no results .

You good fellas shouldn't have to play with anything to get nice consistant cold air. We are in the tropical 90 and I have perfect cold air all the time. Something has caused a loss of coolant and it should be taken care of without question. FWIW Russ

Jim I assume you've got the standard AC, not ACC. Your symptoms donot sound like a coolant level issue, but rather an electronic air mixing, sensoror thermostatproblem. Perhaps an overheating component. Computer diagnostic testing should pinpoint any problems in those areas. Let us know.

I'll be pursuing this with the dealer too. Yes, mine is the standard AC, not 'climate control'. Yes, if you play with the temp setting you can sometimes get a cold response. My guess was also that the fault is in the control system. I'll report any progress. I did bring it up before with the dealer, and they got the thermometer out and found it made cold air, and that was the end of their concern.

Rick: You're right. I had the opportunity to try your one-minute-on-max trick and, sure enough, the cold air returned when I went back to normal A/C. Dan: Yes, I have the manual A/C, and I think you and rsgl are correct about the problem being somewhere in the control system, rather than with the coolant level; otherwise I couldn't get cold air anytime. Thanks for your inputs.

Jim, the manual A/C may well indeed have a control malfunction. Best of luck. I have the coldest air with my auto A/C that I ever had in a car so your expectations should be very high.

Great info in this thread, this just happened to me this weekend and I couldn't figure out what happened b/c it had been SO cold before. I will have to do the one-min-max trick thanks.

YLW GATR: Going to Max for a minute and then back to normal, did return the cold air, but it only lasts for another cycle of going from cold to tepid. On a 125-mile trip back from an autox yesterday I went to Max 3 times during the trip in order to stay comfortable in 85-degree weather. Also, when going to Max, the air remained tepid, but returned to cold once I went back to normal A/C. I talked to the service manager at my Porsche dealer about this this morning. I gave him some info posted here, including the one-minute-at-Max trick. He agreed that it must be a control problem, because they checked the refrigerant level last time. He siad that he would search his sources for a red flag on this problem, and give me a call.

Update; car was taken in for AC check and it was reported to me that leaks were found at a couple of o-ring-sealed points in the system. Said o-rings were reported to have been replaced and the system recharged. AC operates differently now; the cold-production is consistent over time. It is sufficiently cold too, though I still feel it could be colder. So; get your system checked for charge and leaks..... Rob

Jim, did your AC problem get resolved?

I have an appointment at the dealer's Monday. The service manager said he could not track down any previous A/C problem consistent with my description. This time they want to send me off in a loaner, so I guess they anticipate spending some time tracking down the source and don't want me hanging around that long.

A/C report. The Porsche techie said everything checked out fine again (no fault code, no leaks, etc.). We did go for a 20-minute drive, and his probe thermometer poked down the A/C duct went from a reading of 40 degrees to 46 during that time. The cockpit stayed comfortably cool, however. My assignment was to buy a similar thermometer and keep tabs on the duct temps. I bought one on the way home (a 50-minute drive) and installed it. It read 60 degrees in about 5 minutes, and stayed there the rest of the way . The air turned tepid during the trip home, rendering the cockpit uncomfortably warm. And this time Rick's trick (going to Max Cool for a minute, then back to normal A/C) had no effect. Ambient temperature in Roanoke was 92-93 degrees; 87 degrees when I got up the mountain. I'll keep the thermometer in the duct and keep records for a while. Now I'm wondering about the fan. After the air turns tepid, when I turn the fan up, the fan noise increases, but the air flow from the vents doesn't seem to change.

So interesting, keep us posted Jim please; thank you.

Jim, I can see the techs problem. My suggestion - move back to NM in the mountains where you don't need the AC...just kidding I hope you find it soon.

I took another test drive late this afternoon. Initially the duct air temp was 30 degrees; gradually moving up to 50 degrees after 50 minutes of driving. The outside temp went from 86 degrees initially to 76 degrees as it clouded over near the end. Cabin temp went from a low of 72 degrees up to 78, but it was only 76 degrees outside. Thus, I have emperical evidence that the air becomes more tepid across time. I'm more convinced than ever that it's a control problem; something not opening or closing when it should; maybe due to a bad thermostat. Santa Fe: I read in Pano that Fiesta del Porsche was moved from Santa Fe to Albuquerque this year, and that the Roadrunners are also known as the Flying Tamales. Shouldn't that be Frying Tamales?

My latest hypothesis regarding my A/C duct air gradually going from an initial 30 degrees to an eventual 60 involves operator error. Turning down the temperature setting to no bars on the temp dial and running the fan at very low speed may be freezing up the condenser. Air duct temp starting out below freezing (30 degrees) and abnormally large puddles of condensation water after long drives are consistent with that hypothesis. I posed that possibility with an old Porsche mechanic friend (someone who doesn't even have the fancy OBD II reader) and he thought that might be the case. He suggested that I try mixing the cold air with a little warm air (setting the temp several bars up the scale) and using a little more fan speed. I have tried that several times with good results. I have not been able to complete a more definitive test of the new settings because ambient temps here have been in the 70's to low 80's recently. Those with manual climate control, where do you set your temp and fan bars on their dials on a very warm day?

I just passed @k. I went to Sanat Barbara from San Jose last weekend and the AC worked fine. I took ot out yesterday and it just blew warm air. I have ACC. I fiddled with the controls trying ever combination for 20 minutes w/o any change. I'll take it in in a couple of weeks and also have them fix the rattles.

Sorry, just saw my typing errors.

I assume you meant a frozen evaporator, not the condensor. From working in my father's AC shop a few summers, I can tell you that freezing of the evaporator classically is caused by low freon. Can also be caused by a faulty expansion valve and rarely by contaminated freon (e.g., moisture in the gas). Can also be caused by a blockage of airflow through the evaporator. There is clearly something wrong with the system. They may have to find someone more experienced in AC systems to get it fixed. There should be no setting you can set to cause it to freeze because the evaporator should have a sensor that shuts down the compressor when the evaporator gets too cold. Because your symptom is loss of cooling after a period of time, it does sound like the evaporator is freezing (assuming it is not in the control circuitry). So they have to find what is causing it to freeze up. Good luck.

Just dropped my CS off at the dealer for the first time for some issues one of which is poor A/C performance. I'll let ya'll know if they get it corrected and the details. My problem with the A/C is slightly different than the issue in this thread. My A/C will (often times) start out warm and it'll stay there unless I fiddle with the controls or the venting or Max A/C. Then it'll usually cool down...although not enough to my liking. The coldest this A/C has ever achieved is 41 deg F (Recirculating) and it doesn't matter if it's 70 or 100 outside. The service writer said this is the normal temperature for A/C but it's definitely the warmest A/C I've ever owned!! (this is my first R134) When it starts out warm, as described above, it maintains 59 deg F (taken at the center vent). There are times when it'll warm up while driving (59 deg F) but usually jerking with the controls or the venting or Max A/C will get it to cool back to 41 deg F. It has also warmed up while waiting at a red light and from time to time emits an odor while driving. The odor issue has just started approx 100 miles ago. The car has 1.5 K miles on it now so I assume anything that is going to burn off has already done so. Lastly, if I leave the A/C set to Recirculate, it'll maintain this setting whenever I make a stop somewhere and return shortly thereafter. However, if left overnight, it'll reset back to Outside Air. Don't know if this is a problem or a feature. 'First Porsche ' Man Edited by - Cayman_S on 09/19/2006 4:18:52 PM

Maybe my hunch about the evaporator freezing up (I said condensor, but Robert corrected that) and/or plan to avoid that was off. Driving back from an autocross for two hours, I started with four temp bars showing (instead of none) and half the fan bars showing. That also resulted in cool air turning tepid across time. The A/C duct air went from 40 degrees to 60 degrees in about an hour. It stayed at 60 degrees as I tried other settings, including Max Cool, recirculate alone, lowering the temp bars, and adding more fan. The passenger seat temperature eventually got to 88 degrees (I have a separate thermometer sitting next to me); which was several degrees warmer than the outside air. I'll be attending the dealer's open house Thursday, so will give them an update and ask if we can get the regional tech guy in on this problem.