E66 Air Con Issue

E66 Air Con Issue

Author
Discussion

Matt14

Original Poster:

10 posts

153 months

Wednesday 14th June 2023
quotequote all
Hi all,

Please help if you can. My air con wasnt working when bought the car. Had it regassed, (was low), held pressure & no leaks.

The fan is running but when I turn on the air con - no cold air

Thought it might be teh compressor had gone bad. However, with my limited scan tool I could run a service program for running in the compressor after a regas and SURPRISE SURPRISE Cold air (more from one side than the other).

What I am taking from this is as follows:

1. Air con pressure ok and no leak
2. Compressor is good just not being switched in for some reason
3. The fan is running so thats not the problem
4. In addition to the compressor not kicking in, there is probably a valve issue as half of the car much colder than the other

Would anyone be kind enough to suggest any ideas as to what the issue might be.

Many Thanks

Matt

NMNeil

5,860 posts

57 months

Thursday 15th June 2023
quotequote all
No idea about the distribution of the air but a common fault is the pressure switch(s). If the refrigerant pressure is too low, such as running out of refrigerant, or too high indicating a blockage somewhere, then the switch(s) disables the compressor to prevent damage. The scanner will bypass that switch and operate the compressor directly so that's why it worked briefly.
Common fault, but without a decent scanner, it's difficult to diagnose.

Collectingbrass

2,393 posts

202 months

Thursday 15th June 2023
quotequote all
Do you get any air at all?

Matt14

Original Poster:

10 posts

153 months

Friday 16th June 2023
quotequote all
Thanks for replies

In response - yes get air just hot outside temp, no refridgeration, also checked condensor not running.

Diagnostics as follows:
Temp cont Left 61oF
Temp cont Right 61oF
Outside temp 76oF
Evap temp 104oF
Heater AC On
Function AUTO On
Cold Air flamp motor pos 100%
Hot Air flap motor pos 100%
Power Sup 13.6V
AUC sensor sup 5.02V
AUC signal 5.00V
AUC sensor detection UNKNOWN
Pressure sensor 4.98V
Refridgerant pressure 6.51 bar
Compressor refridgerating capacity 0%


My read from all of this was that the AUC sensor isnt working. I thought that normal should be less than 2.5V



Matt14

Original Poster:

10 posts

153 months

Friday 16th June 2023
quotequote all
any help much appreciated - diagnosing bad air con not my strong point