MarkR171

My A/c hasn't cooled for months. Now that I have time to work on the car, I've been trying to diagnose the problem. I opened the hood to check if the compressor engages and it does fully engage. I pulled the readings through the climate control diagnosis and my refrigerant levels are right on point (3.3 bar.)

However, the evaporator temperature sensor reading was at 135* F. I changed the sensor out for a new one and got a more reasonable 85* F reading (close to current outside temperature.) However, after running the engine/ac, the evaporator temperature does not come down. I understand the evap temp should drop considerably as it cools.

I checked a/c codes through the climate control diagnostic and only came out with one code: 421 (Pulse Module[?])

So this is where I stand:
- AC blows but no cooling
- Heater works, gets very hot
- Compressor engages
- Fan turns on
- Refrigerant pressure reads 3.3 bar through diagnostic menu
- Only one code: 421 Pulse Module (what is this?)
- Evap does not cool down with engine running

popey24

Whitch sensor did you replace, there are many...?

If your evaporating pressure really is about 3 bar, your evaporator must be pretty cold.

Do you have standard or comfort A/C control unit?


System seems to work well from what you wrote... you sure you turned off the heating system?
The pulse module probably is the valve we call 'Duoventil' in Germany. It is responsible for hot water mixing. Maybe thats your problem. I think you can test it manually.