Lack of cool air from ACC on 83 300D - PeachParts Mercedes-Benz Forum

ifari · #1 03-28-2006, 01:11 PM

Greetings, I have spent much time trying to find a solution to my problem and greatly appreciate this forum.
I am the owner of a much admired MBZ 1983 300D. (Ok, it's admired by me mostly, but you know what I mean!) It has been mine for 15 months and 45k miles. With a fairly new suspension and its great ride and build quality, I am a new Mercedes afficianado.
My problem seems to be a lack of cool air on either EC setting or otherwise. Lots of heat but no cool air. The monovalve has been looked at and there is no rip in the diaphram. Is there something else that could be the problem?

Thanx.

dannym · #2 03-28-2006, 01:16 PM

Ok, first.....go to the USER CP and put your location and vehicle info into your profile. Then I wouildn't have to ask what climate you live in.

has the air conditioning ever worked?
Does it have a charge?
Do you have gauges to test it?

http://www.peachparts.com/shopforum/showthread.php?t=127342

Danny

ifari · #3 03-28-2006, 04:31 PM

I am in Canada.
Yes, the AC has worked. It was converted to 134. Not too cold at best, but better than now.
No, I have not tested it or have a meter.

Diesel Giant · #4 03-28-2006, 05:00 PM

You should do some basic tests and then see where you are at. Look at this pictorial to help you on the A/C.

http://dieselgiant.com/repairyourac.htm

ifari · #5 03-28-2006, 06:48 PM

Giant, I have a copy of your article. Very helpful in describing the full extent of what could be done.

Are my symptoms synonymous with compressor failure? The compressor had been changed in 03. What about the absence of cool air with the EC setting?

Thanx.

dannym · #6 03-28-2006, 08:25 PM

You can easily test the compressor by jumping out the switch on the receiver dryer. One will start the aux fan the other will start the compressor. Just bump it don't let it run for long.

134A need a critical charge it may just be low.

The EC, Economy, setting uses outside air only. That is the only button that WILL NOT turn the compresor on.

Danny

Diesel Giant · #7 03-28-2006, 08:34 PM

Danny is correct. In EC the compressor does not turn on, but I think you say it does not work on any button. You need to see if you have voltage at the low pressure switch when the A/C is turned on. If you do, then you will jump the switch and see if the compressor will engage.

At that point you could have a low charge or bad low pressure switch.

So do those test and then report back on the results.

ifari · #8 03-28-2006, 09:52 PM

I'll have the tests done soon. Thanks for the input.

ifari · #9 03-31-2006, 10:38 AM

Thanks again for the advice guys!
I did as you said and had the compressor checked. It appeared that there was no electricity reaching the compressor. The technician suspected electrical fault, but it turned out that the clutch needed a slight tap with a hammer

to engage properly. The AC system was drained and recharged with 2lbs. of R134.
I was also told that I needed a condensor fan as the one I have is inoperative. The fan I was told is needed for correct operation in stop and go traffic. It should put less strain on the system if the fan is working properly. All in all a very satisfactory result.

Thanx.