Junius

Hello everyone, I've been having some intermittent problems with my a/c system. After my car had its timing belt and cam chain repaired, my a/c worked for two days perfectly cold but then afterwards was not blowing cold air as it should. It was actually uneven as the passenger side was colder than the driver side. So my mechanic evacuated the system then refilled with freon, and it worked good for another 2 days then was not getting as cold again. Seems like the compressor works good but I noticed one of the a/c lines condenses and freezes up and then drips water after the engine is turned off. I also hear a slight hissing sound when the engine is turned off (not the air suspension) Any ideas of what this could be?

Junius

TSHong

Sounds like you have a leak in the system somewhere. Your mechanic should be able to find one that large.

Mister Bally

Standard automotive air conditioning troubleshooting techniques apply. What are the suction and discharge pressures at idle and at 3000 rpm with a/c set to low? Be sure to let us know the ambient temperature when you are reading the gauges.

GradecEngineering

+1 to what Mister Bally said. That's step #1. Don't waste your time anywhere else.

Did your mechanic mention the cap is missing from that port? That's allowing contaminants to build up on the inner walls of the ports which eventually get pulled in during a recharge.

Junius

I did mention that and they forgot to put one back on. Could I just buy one from the dealership? I also will take the car to get its A/C tested soon and will let you know those temperatures. I am also wondering if this problem has anything to do with the fact that I've noticed air in the coolant system? When I open the cap after a hot drive, a good amount of pressure is released from the top of the reservoir.

TSHong

The pressure in the cooling system is normal. It is actually dangerous for you to ope then system right after you stop the engine. The only way your cooling system can effect the AC is if the engine was overheating and that would shut the A/c system down.

GradecEngineering

Dealership? Spend much there? You don't even have to leave your house:
http://www.ebay.com/itm/R134a-Automotive-A-C-Service-Port-Cap-SET-HIGH-LOW-SIDE-RED-BLUE-/171896416157?hash=item2805d3279d&vxp=mtr
The coolant system in your D3 is indeed a pressurized one. When you open the reservoir cap you should expect the system to depressurize, or rather come down to atmospheric pressure. It's thermodynamics. It's normal.

Junius

Thanks for the replies. I will definitely get those port caps as soon as possible. Also, not to familiar with the cooling system, so thanks for the information. My A4 never depressurized when I opened it, nor changed levels either. I scanned the car yesterday for any stored codes with the Carista app and it stated 00819 for High Pressure Sensor (G65) under the Air conditioning/heat category. I wonder what that means?

Mister Bally

Either the a/c system is overcharged or the high pressure safety switch is defective. Based on the icing/frost; it appears overcharged. As mentioned earlier, Standard automotive a/c troubleshooting techniques apply here.

What are the suction and discharge pressures reading at idle and at 3000 rpm and what is the ambient temperature?

Or, contact Carista for diagnosis. Ross-tech offers some troubleshooting assistance to those who buy their product.