[W126 Coupe] Air Conditioning Diagnosis

[Dick Spellman]

Dan Landiss wrote:

> on 6/11/2007 11:25 AM Dick Spellman wrote:

>> Are you saying you had vent temps of 25F?

>

> No, the gauge is calibrated in both PSI and degrees. I rarely see vent

> air temps below 60F.

>

Hi Dan:

So, was the low side pressure within spec based on outside ambient air 
at the time you tested?  If it was in spec, I'd be right at the vacuum 
switching valve testing those vacuum elements to see which ones are 
leaking.  In particular the fresh air/ recirculation flap elements.  I 
know you are dealing with the passenger air bag which makes that job 
very difficult but, if it's open more than 20% while AC is called for 
that is definitely watering down your cooling so to speak.  There is 
also the much difficult to get at (with pass airbag) vacuum element that 
directs air flow between center vents and defrost vents.  This too fails 
and you hear the blower running at high speed and feel little air in the 
cabin.  That's because it fails over to the darn wind screen when the 
leak on the diaphragm occurs.

If it's not in spec for low side pressure well, top off the R-12 or push 
the R-134 to 80% of the R-12 capacity on the radiator support label.

Let me know what you find or feel free to give me a call at 508-641-8477 
EST.

Dick