My parent's 94 C280 is currently undergoing a/c woes. The a/c is not blowing cold air even after a recharge, and all you get is what seems to be outside air. Their mechanic told them that the push button unit needs to be replaced. The price quoted for the part is $840, plus labor. I promised my parents that I will do some research on the a/c problem before they fork out their retirement fund.

Last night I tried this display diagnostics. My question is, how do you interpret the numbers from the climate control display diagnostics? For example, with the engine off but the ignition at ON position, I'm getting numbers that are quite different from David Klasse's example. Some of my numbers are as follows - I'm working from my memory.

7 - Refrigerant Pressure in Bar - 04.3
8 - Blower control voltage - 21.0
9 - Software status of a/c Pushbutton control module - 02
22 - Terminal 58d (Bat Volt) - 0.00

I will try to get more detailed numbers tonight, i.e. standstill vs driving and at HI, LO, 72 degrees. But, I still need to know how to interpret these numbers. For example, is David Klasse's numbers the norm?

Any help you can provide would be greatly appreciated.

Edward

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Edward Cho
Menlo Park, CA
1983 Porsche 944
1995 C280