Air conditioning not working - mechanic says need new AAM?!
My wife's '98 ML 320's A/C stopped working about a month ago. As we had some bad experiences with the dealer we took it to a one-man shop german car mechanic.
He did his thing, refilled the system, etc., and said the compressor wasn't engaging.
Finding no reason for it not to turn on, he cleaned the contacts on the connector to the compressor from the harness, and the A/C compressor came on.
He said he hoped this was the problem because if the A/C compressor stops working again it could only be because there is no signal to it from the AAM (all activity module). And that a new AAM would cost around $900 for the part only.
Yesterday, the A/C compressor stopped working again.
if it's the AAM, shouldn't he have more problems than just the AC?
Good question. Also, I just went outside to move the car [my wife had dropped it off at my work and it had been sitting for several hours] and the A/C's working again. Of course, it'll probably stop working when I have to drive home. :-(
I don't think this is an AAM problem. Think about it, your A/C did not start working again until your mech. recharged the system and cleaned the plug to the A/C clutch. Doing either one of these things would not miraculously make the AAM work.
While the A/C is working, open the hood and look at the A/C compressor and see if the clutch is cycling on and off. If it is you are probably low on refrigerant and have a leak somewhere.
I had similar A/C experience a long long time ago with other car.
It was frozen evaporator and it blocked the air flow route and the compressor was overloaded and shut off not to be overload too much.
When I warmed it up by not using A/C, it melted down and worked again. But soon, it didn't work and got frozen.
I think it was because of moisture inside of the system, but not sure why,how.
I don't think this is an AAM problem. Think about it, your A/C did not start working again until your mech. recharged the system and cleaned the plug to the A/C clutch. Doing either one of these things would not miraculously make the AAM work.
While the A/C is working, open the hood and look at the A/C compressor and see if the clutch is cycling on and off. If it is you are probably low on refrigerant and have a leak somewhere.
Thanks, when he first messed w/it a month ago he said the system was actually slightly overcharged and that that might cause the compressor to not work, so he evacuated and recharged the system. I assume he checked for leaks at the same time, but maybe he didn't...
I had similar A/C experience a long long time ago with other car.
It was frozen evaporator and it blocked the air flow route and the compressor was overloaded and shut off not to be overload too much.
When I warmed it up by not using A/C, it melted down and worked again. But soon, it didn't work and got frozen.
I think it was because of moisture inside of the system, but not sure why,how.
Thanks, I'll drive it myself for a few days to see how it acts (it's my wife's car).
Well, I just drove it home. It worked fine until I parked it at the grocery store. When I came out of the store and restarted the car the A/C blew ambient air (it's hot here in SoCal). Then after about 2-3 miles it started blowing cold air again.
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