Mercedes-Benz Forum banner

1 - 4 of 4 Posts

·
Registered
1990 500SE
Joined
·
447 Posts
Discussion Starter #1
Is there a set outside temp that must be reached before the a/c engages ?.

scenario: I was driving the Benz this afternoon on a 500 km. road trip back from Vancouver, B.C. Outside temps where in the 17-18 C temp. It was quite sunny and the interior was getting warm due to the sun. Up to now it had never been hot enough for me to use the a/c as I had bought the veh. about 3 months ago. I had the temp dial at 65 F ( American model ) and the auto climate set at Auto low. There was air coming in from all upper vents. Due to the warmer interior temps I deceided that this would be a good time to see if the air cond. works. I put on the air cond. switch and then felt more air come out of the upper vents at a higher rate of speed. The air never got any colder and it felt like it was just outside air coming in due to highways speeds.I flicked the a/c switch on and off several times and did not feel any drain on power as when the compressor kicks in on my other newer veh. I did not know the exact outside temp but guessed it to be in the 17-18 C range ( around 65 F ) .
Now the question is, was it still not hot enough outside for the a/c compressor to kick in as it was around the 65 F mark which is the lowest on the dial, or does the low outside temp have nothing to do with the a/c switch control ?. Maybe I'm out of freon or there is something wrong with my a/c.

just curious.
 

·
Registered
1983 300D Turbo!!!!
Joined
·
19 Posts
Im sure other people on this forum would agree the w123 300D models AC was its' weakest attribute. Having recently replaced my compressor and other various equipment related to the AC. I would venture a guess that your compressor needs a recharge or has died. I would suggest placing the dail to the coldest setting "min" which would be below 18c. If the AC does not blow cold then recharge or replace the compressor. I would recommend a complete rebuild if you have the $$$ as these systems lines are notorious for small leaks which will plague you if not done correctly.

Good luck with your AC
 

·
Registered
'82 300D
Joined
·
1,279 Posts
If your freon level is good, the compressor should engage. In winter mine engages, but cycles a lot. As the ambient temp comes up, it cycles less.

Have you checked the freon level? Have you seen the compressor engage while standing outside, and engine idling?
 

·
Registered
1990 500SE
Joined
·
447 Posts
Discussion Starter #4
Update.

Over the last few days I made local checks at garages to see if anyone had any R12 and was willing to check out my a/c in the old Benz. I knew of a Mercedes repair shop about 3 hrs drive from me and he wanted about $100 to recharge the freon ( R12 ) if that was all it was. Well I went to a small shop who gave me a phone number of a guy who still can deal with the old r12 refridgerant. He was only 20 miles away. I called him and set up a time the following day. I went to the fellow who was an old refridgerant guy from way back ( also fridges, freezers etc. ).
Anyway he hooked up some guages and told me that my pressure in the a/c was low, meaning that the freon was low. He checked for leaks and found none. He pulled out this old 10 lb propane looking bottle ( r12 written on the side ) and hooks up some pipeing and told me to put on the a/c to the highest point while engine running. He also put a temp guage into one of my outside air vents in the dash to check the temp. of the a/c. After 10 minutes , he stopped the flow of freon and unhooked his hoses. at this time I checked the flow of air coming out of the vents and it was cold. His temp. guage from my vents read 40F. He said that this was very good as most newer cars he works on get anywhere from 45-50F ( r134 ). All connections were checked and all was good. I was happy that it was just low on freon.

Here's the nice part. He only wanted $ 40. for his charge. he also said that he was impressed that an old a/c system like this was in such good shape and easy to work on.

On the way home it was already 25 C and I used the a/c and it was enjoyable to have it working as it really cooled the cabin. this really makes me want to go on long trips now in the heat of summer.
 
1 - 4 of 4 Posts
Top