A/C Issues

[Scott McKinney]

My air conditioning has intermittently been working since I purchased the vehicle but seemed to be getting worse and worse about blowing cold. It is a dual zone automatic climate control system. Sometimes I can get it to blow cold but constantly fooling with the settings, modes, and fan speeds but lately it is very hard. I am 99% sure that the A/C compressor is cycling because there is a change in pitch in the engine when I turn the temperature low, but still no cold air coming out of vents. I put 1.5 cans of freon in the system with a simple can & hose, but it will not accept any more, so I assume its full. Any common issues or things to try and fix this without an expensive trip to the dealer? I appreciate your help! Please advise.

[JFP in PA]

My air conditioning has intermittently been working since I purchased the vehicle but seemed to be getting worse and worse about blowing cold. It is a dual zone automatic climate control system. Sometimes I can get it to blow cold but constantly fooling with the settings, modes, and fan speeds but lately it is very hard. I am 99% sure that the A/C compressor is cycling because there is a change in pitch in the engine when I turn the temperature low, but still no cold air coming out of vents. I put 1.5 cans of freon in the system with a simple can & hose, but it will not accept any more, so I assume its full. Any common issues or things to try and fix this without an expensive trip to the dealer? I appreciate your help! Please advise.

 

First of all, simply adding gas to a system without knowing what pressures it is already at (particularly the high side in relation to the ambient air temps)is asking for a disaster.  There are ways to test these systems to determine if the current gas charge is correct or not.  You may have already over charged the system which could cause it to go into very expensive and potentially dangerous component failure.

 

Separately, your multi zone control system may be stuck or malfunctioning, which could be the basis of your original issue.  If you do not understand these systems, or lack the diagnostic equipment to work on them, take the car to a pro who does, before you make a bad situation worse.

[Scott McKinney]

That is what I am requesting, how to test them and fix this issue myself. I know how to take it to a dealer and pay the bill, but am more interested in learning and fixing it myself.

I have access to A/C pressure gauges I can hook up and just purchased a Durametric scan tool. Any help on diagnosing my issue is greatly appreciated. Please advise.

[JFP in PA]

That is what I am requesting, how to test them and fix this issue myself. I know how to take it to a dealer and pay the bill, but am more interested in learning and fixing it myself.

I have access to A/C pressure gauges I can hook up and just purchased a Durametric scan tool. Any help on diagnosing my issue is greatly appreciated. Please advise.

 

Are the gauges you have 134A or are they set up for R12?

 

You will need access to the factory service manual for the system in order to look up the correct pressure/ambient temperature relationships and reset the pressure correctly.  If the system is already overfilled, you will need access to a certified gas recovery system to remove the excess gas to get down to the correct levels.

 

The Durametric system is capable of reading and diagnosing AC systems, but the level varies by model and year somewhat.

[Scott McKinney]

Here are my current readings, any opinion?

Edited June 1, 2016 by Scott McKinney

[JFP in PA]

Here are my current readings, any opinion?

 

Is that with the car running?

[hahnmgh63]

As JFP said, need the A/C on High, temp set to lowest temp to keep the compressor engaged maximum time to get a better reading of true High & Low pressures.

[lewisweller]

The AC gas volume is 700grams for non 4 zone and 1050grams for 4 zone AC systems on all cayenne 955.

The gauge won't tell you how much gas you have filled and by looking at you low pressure gas gauge it's go too much in it I think.

Best to drain the whole gas out and only add the exact amount when recharging.

An AC machine would such out the old gas check for vacuum pressure hence any leaks and then re-gas the correct set amount you tell it.

Many places do AC repair except the stealer, I would also recommend you take it to one for peace of mind and safety, the gas is not healthy for humans!

The garage I took mind too had an issue with the low pressure connection NRV and the muppet told me there wasn't any gas in it, I told him impossible or the AC wouldn't blow any cold but it was working Ok ish. Turns out the muppet in question then proceeded to add 1050 on top of the 700 he mistakenly put in a few day before (he thought it was dual zone not 4 zone). So the low pressure gauge read some incredible figure and the compressor would work. I got his manager out to bollock him and they drained the 1750g out and re-gassed with 1050g and all was perfect.

I live in dubai, AC is pretty important; the "mechanics" here have some of the gear but no idea. Lol

[lewisweller]

The AC gas volume is 700grams for non 4 zone and 1050grams for 4 zone AC systems on all cayenne 955.

The gauge won't tell you how much gas you have filled and by looking at you low pressure gas gauge it's go too much in it I think.

Best to drain the whole gas out and only add the exact amount when recharging.

An AC machine would such out the old gas check for vacuum pressure hence any leaks and then re-gas the correct set amount you tell it.

Many places do AC repair except the stealer, I would also recommend you take it to one for peace of mind and safety, the gas is not healthy for humans!

The garage I took mind too had an issue with the low pressure connection NRV and the muppet told me there wasn't any gas in it, I told him impossible or the AC wouldn't blow any cold but it was working Ok ish. Turns out the muppet in question then proceeded to add 1050 on top of the 700 he mistakenly put in a few day before (he thought it was dual zone not 4 zone). So the low pressure gauge read some incredible figure and the compressor would work. I got his manager out to bollock him and they drained the 1750g out and re-gassed with 1050g and all was perfect.

I live in dubai, AC is pretty important; the "mechanics" here have some of the gear but no idea. Lol

[weapons777]

The AC gas volume is 700grams for non 4 zone and 1050grams for 4 zone AC systems on all cayenne 955. The gauge won't tell you how much gas you have filled and by looking at you low pressure gas gauge it's go too much in it I think. Best to drain the whole gas out and only add the exact amount when recharging. An AC machine would such out the old gas check for vacuum pressure hence any leaks and then re-gas the correct set amount you tell it. Many places do AC repair except the stealer, I would also recommend you take it to one for peace of mind and safety, the gas is not healthy for humans!The garage I took mind too had an issue with the low pressure connection NRV and the muppet told me there wasn't any gas in it, I told him impossible or the AC wouldn't blow any cold but it was working Ok ish. Turns out the muppet in question then proceeded to add 1050 on top of the 700 he mistakenly put in a few day before (he thought it was dual zone not 4 zone). So the low pressure gauge read some incredible figure and the compressor would work. I got his manager out to bollock him and they drained the 1750g out and re-gassed with 1050g and all was perfect. I live in dubai, AC is pretty important; the "mechanics" here have some of the gear but no idea. Lol

Thanks for the info lewisweller.

May I ask where did you take your car in Dubai? I live over here as well and I'm having problems with my AC not cooling when parking the car in the sun.

When the car sits in the sun for a while the AC fan would not even start despite being in the Coldest setting.

[lewisweller]

I won't mention the garage and wouldn't recommend you either.

I suggest you go to z-degrees in al quoz for AC gassing but you say the fan doesn't work so that has to be fixed ofcourse. If the AC works OK when driving I would say the AC gas and compressors etc are Ok. It is just the fan not running which is the problem.

Go see chad at Motor Mec 050 739 10 33, also in al quoz just around the corner from Porsche service centre in fact.

we should meet up I really got to see what another ctt drives like compared to mine, I think mine is a bit rough and under powered, but I might be used to my audi which is F quick and expecting too much from this heavy beast. Lol

[weapons777]

I won't mention the garage and wouldn't recommend you either. I suggest you go to z-degrees in al quoz for AC gassing but you say the fan doesn't work so that has to be fixed ofcourse. If the AC works OK when driving I would say the AC gas and compressors etc are Ok. It is just the fan not running which is the problem. Go see chad at Motor Mec 050 739 10 33, also in al quoz just around the corner from Porsche service centre in fact. we should meet up I really got to see what another ctt drives like compared to mine, I think mine is a bit rough and under powered, but I might be used to my audi which is F quick and expecting too much from this heavy beast. Lol

Thanks for the quick reply and your recommendations.

Yeah, the AC fan is driving me nuts as it only happens when the car sits in the sun. If the car is parked in the shade then it works fine.

Anyways I'll have the guys replace the gas.

Currently out of the country but happy to meet if you want to test mine.

[lewisweller]

Weapons777

Are we talking about the engine compartment radiator fan or the blower fan inside the car no working properly?

[lewisweller]

If it's the interior AC blower fan then change the regulator, renowned for intermitted problems. Remove the glove box and the fan unit can be accessed and removed with regulator. At the same time clean and lube the fan motor bearing.

[weapons777]

If it's the interior AC blower fan then change the regulator, renowned for intermitted problems. Remove the glove box and the fan unit can be accessed and removed with regulator. At the same time clean and lube the fan motor bearing.

Thanks for your help. It's the internal blower failing intermittently. Specially when it's really hot outside.

I'll try replacing the regulator and lube the bearing to see if that fixes my problem.

[lewisweller]

Try this link for glove box removal

http://www.pelicanparts.com/techarticles/Porsche-Cayenne/30-BODY-Glove_Box_Catch_Replacement/30-BODY-Glove_Box_Catch_Replacement.htm

And this link to replace the regulator

http://www.pelicanparts.com/techarticles/Porsche-Cayenne/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement.htm

[weapons777]

Try this link for glove box removalhttp://www.pelicanparts.com/techarticles/Porsche-Cayenne/30-BODY-Glove_Box_Catch_Replacement/30-BODY-Glove_Box_Catch_Replacement.htmAnd this link to replace the regulatorhttp://www.pelicanparts.com/techarticles/Porsche-Cayenne/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement.htm

Thanks. I came across those links on Google as soon as you mentioned the fix.

Nice tutorials by the way.

[nerdtalker]

 

If it's the interior AC blower fan then change the regulator, renowned for intermitted problems. Remove the glove box and the fan unit can be accessed and removed with regulator. At the same time clean and lube the fan motor bearing.

Thanks for your help. It's the internal blower failing intermittently. Specially when it's really hot outside.

 

 

That's the same failure mode my Cayenne had as well, when the vehicle was hottest was when the regulator seemed to die or be most intermittent and lock out the highest fan settings. The system would then see inadequate cooling and request an even higher (broken) fan state from the regulator, until it reached maximum, all while barely blowing any air through. I think mine might have frozen a few times since it wouldn't blow at all. 

 

I replaced my fan regulator and now I have awesome cooling and all of the fan states all of the time. 

 

Troubleshooting this was strange since I could be in a parking garage and have all the fan states, but right when I needed the highest fan states (after being parked in direct sunlight) most they would be unavailable. 

[weapons777]

If it's the interior AC blower fan then change the regulator, renowned for intermitted problems. Remove the glove box and the fan unit can be accessed and removed with regulator. At the same time clean and lube the fan motor bearing.

Thanks for your help. It's the internal blower failing intermittently. Specially when it's really hot outside.

That's the same failure mode my Cayenne had as well, when the vehicle was hottest was when the regulator seemed to die or be most intermittent and lock out the highest fan settings. The system would then see inadequate cooling and request an even higher (broken) fan state from the regulator, until it reached maximum, all while barely blowing any air through. I think mine might have frozen a few times since it wouldn't blow at all.

I replaced my fan regulator and now I have awesome cooling and all of the fan states all of the time.

Troubleshooting this was strange since I could be in a parking garage and have all the fan states, but right when I needed the highest fan states (after being parked in direct sunlight) most they would be unavailable.

Glad to hear mine is not an isolated case. Looking forward to replacing the regulator once I receive it and lubricating the motor bearing.

Will post my results after the fix.

Thanks everyone.

[weapons777]

Well. I've replaced the AC fan regulator and lubed the fan bearing. Fan is working properly even when car is seating in the sun.

Had the AC gas checked as I feel the system is not cooling enough.

I was told by the technician, the gas quantity is fine but he said the compressor is weak (not generating enough vacuum) and needs replacement. He showed me the low pressure reading of 51 psi. According to him it should have been between 20 - 40 psi.