Pkcayenne

Thanks for your advise I'm hoping someone with a cayenne will have experienced this issue before taking it to a specialist or stealer ship will keep searching and post the resolve to save the next person experiencing this issue.

griffiths

Sounds like an intermittent electrical fault; could be a poor connection or failing device.

If the vehicle is out of warranty I can understand the financial issues of
having a dealer spend time with it.

You could ask Porsche experienced repair shop what it would cost to
runs a few diagnostics tests on the system; who knows, if they aren't busy they might do it reasonably.

Or, you might explore what diagnostic tools are available in the aftermarket,
for example, Durametrics suggests their OBII scanner can read AC codes however it can't give values.
Exploring something like that might be valuable if you intend to keep the car and work on it yourself.

Pkcayenne

HI all resolved myself with a 10$ Temp vw sensor from eBay please check my other post 15 min job unplugged the old going through the firewall under the glove box, not to complicated saved me lots of cash not going to the stealer ship.

Pkcayenne

Thanks all this forum has helped me out over and over

ScootCherHienie

There is no such thing as "freon". "Freon" is a registered trademark of Chemours Company for a family of refrigerants... R12, R13B1, R22, R502, and R503. Refrigerant used in auto air conditioning systems since about 1995 is R134a and is NOT 'Freon'. Those cans of refrigerant you can buy at auto parts stores are VERY DANGEROUS to your A/C system. The main reason is that the pressure you read on the valve is VERY dependent on whether the A/C compressor is operating or idling. Because of the way modern A/C systems work, the compressor idles about as much as it operates and it can turn on and off frequently (there is an electrical clutch for this). Because the compressor can engage for 3 seconds, then disengage (does not run with the electric clutch disengaged) for 10 seconds or even more, you can have very small windows of time where the pressure reading at the valve is correct. Doing pressure measurements when the compressor isn't running gives the wrong pressure measurement and you can WAY over-pressurize the A/C system with one of those cans of refrigerant. Frankly, the ads on TV that make it look so simple... that company should be taken to court and sued for false advertising. No telling how many A/C systems have been damaged using those things. It is freakin' hard to keep an eye on the compressor AND watch the pressure for the A/C system at the same time so you can EASILY think you are reading pressure correctly, but you aren't. That's when the over-fill disaster can strike. Some of the products claim that putting the A/C system into "Maximum cool" mode and the temperature setting to the coldest available setting will make the compressor run continuously, but that is simply not the case. The compressor will STILL cycle on and off with the system set for Max cooling. As others mentioned, the only right way to do this is to evacuate the system and refill with "fresh" refrigerant by weight. You then check the low side and high side pressures to tell whether the system is working correctly... not to tell whether the system has the right amount of refrigerant. If the pressures are not right after evacuation and refill... that means some component in the system has an "issue" and further diagnosis is required. Also, the ambient temperature will affect the pressures you read on the refrigerant pressure gage also. Another way you can end up over- or under-filling.

Pkcayenne

Hi scoot as my previous post was a bad 10$ sensor all fixed

Pkcayenne

Ignore my freon comment was fixing the house ac at the time )

Dylan Laubscher

Pkcayenne

PTEC

Which sensor did you replace?

deilenberger

I'll follow up on Scoot's comment - the factory service manual has extensive documentation on the HVAC systems. And it is multiple systems - if you have 2 zone or 4 zone you have much different systems, and much different pressure requirements. The manual (and undoubtedly AllDataDIY) has charts showing the pressures at various locations in the system, measured with built-in sensors that can be read by the PIWIS, or iCarScan. There are also multiple temperature sensors - again readable with PIWIS/iCarScan. Using the data from the temperature sensors, with the system on MAX-AC, the engine running at 2,000 RPM for at least 2 minutes - you can determine if the pressure readouts are correct. That's about ALL you can do that way - since if they aren't correct - it might be low refrigerant, or it might be another component of the HVAC system misbehaving. There are charts for both the 2 zone system and the 4 zone system - and the correct one must be used.

I thought I was low on refrigerant. I added a bit - and got the numbers up to where it seemed like the charts said they should be - but still wasn't getting the AC that I remembered from past summers. A visit to the dealer determined that I had a contaminated "dryer" (which fits into the condenser coil up front). Replacing that, and then filling the system correctly by weight gave me perfect pressure/temperature readings with the iCarScan - and the great AC that I remembered from other summers.

This is a case where even I - who used to help friends install AC systems in their homes (have the vacuum pumps, gauges, etc..) and installed AC in a number of my cars - was better off having the dealer fix it. It turned out being relatively painless since my extended warranty covered all but my deductible ($100.)

I'd suggest visiting a shop familiar with the Cayenne HVAC - and get it fixed right. In some cases - this may be a dealer only repair job.

josephmd

which sensor did you replace? Can you post a link to it maybe? Where to buy it?