Date registered: Jan 2013
Vehicle: Ex 97 S202 C200 + 02 W163 ML320 + 05 A209 CLK500 + 2011 B8 S4
Mentioned: 0 Post(s)
Quoted: 14 Post(s)
AC won't work in idle - valve?
Not sure if I diagnosed enough for a conclusion - but here it is.
If the car's been parked for a while and I start it and just sit in idle, it won't cool at all.
After driving for a few minutes in more than stop&go traffic, the AC comes on and works fine.
Sitting in dense traffic or at a drive-through etc, it kicks out, gets warm, windows fog up etc.
If I restart the car when it's recently been driven, it sometimes works fine, even sitting in idle for a little bit until it kicks out.
So.. I hooked up STAR and a low pressure gauge - outside temp around 76F, Temp set to "Blue" Cold Auto:
Test1 after recently driving:
- Engine off: >4 bar / 11 bar | 60 / 160 psi
- Idle: 2.7 bar / 13 bar (cools fine) | 39 / 188 psi
- After idling 5 min: 2.3 bar / 13 bar (cools fine) | 34 / 188 psi
Test2 - Engine off / on:
- Idle: >4 bar / 10 bar | 60 / 145 psi
- After idling 5 min: same - as if something just doesn't open, the low pressure gauge stays in the red
- Driving around the block / or just revving for a while: AC kicks in and values are similar to Test1.
Test3 - AC Off button:
- See Test2
Is that the compressor itself? The expansion valve? It may be slightly low on freon, but that doesn't seem to be the cause?!
In either condition the compressor seems to be engaged.. I can hear it yowl and STAR shows it at 100% (50% and dropping with AC OFF)