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W210 E320 A/C Compressor problem

25K views 46 replies 5 participants last post by  BoatWaco 
#1 ·
I am not sure if this thread was posted previously, but I am a new user and am not very sure how to use this site. So anyway, today in blazing hot SoCal (Southern California) I finally replaced my W210's blower motor resistor (early model). The resistor was not sending enough power to the blow motor so in effect not blowing enough air. Read online and seen that alot of people replaced it with the W140 regulator and voila blower works flawlessly. When I purchased the vehicle the resistor was bad so i never really knew how a Mercedes-Benz A/C felt at full speed. Anyway so after a couple minutes i notice that the Air conditioning felt cool but almost as if it needed freon. Silly mistake on my part; I go to autozone and purchase the freon BEFORE checking how much freon is already in the system. (Had the tool in my trunk). I plug it up and it immediately jumps to red so i didnt bother but auto zone wouldnt replace it because i had already screwed it into the tool. So at that point i decided to look down at the compressor and to my surprise, it wasnt turning at all. It was weird because before i replaced the regulator the compressor was definitely on. So I shut the car off and head into auto zone again to ask some questions about why the compressor wouldnt turn on (I know noob mistake I was desperate) and then i go back outside and turn the car on and the A/C is throwing ice cubes in my face! Amazing! But then shortly after the compressor shut off again. I noticed that everytime i shut the car off and turn it back on, the above repeats itself? Can anyone help me? Its going to be 90+ degrees the rest of this week and I would really like to get this thing fixed. Sorry for the long post. Thank you in advance
 
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#8 ·
Don't mean to ignore your comment Eric. We ran some test and singled it out to the actual fan itself. I was completely oblivious to the fact that the fans never even kicked on with the ac. I ran a current test and seen that power was being sent to it to trigger the fan but the fan never responded and the fan on the other side was always spinning. Turns out it wasn't attached to the belt so the air from the engine fan was moving it so I assumed they worked. Anyways I ordered the part and we are patiently sweating I mean waiting for it to come haha. In the mean time I have to drive a dreaded bmw to keep cool ;(
 
#12 ·
Okay Eric since you have helped me throughout all of this I decided it would be fair to update you with what has been going on. At this point me and the mechanic are doing trial and error replacements to single out the issues with the A/C. Now we have replaced the pressure switch and the evap temp switch just to replace any sensors that may be tripping off the system. That didn't work so we got another mechanic in to check it out. He was stumped but diagnosed the compressor as the issue. We got a compressor from a working E320 from the same year, 97, and replaced it. That didn't work either but didn't upset me to much as I only paid 60 bucks for the compressor. So now after eliminating all of those possibilities I'm starting to thing the actual control module is our issue. Because it was only AFTER I did the W210 to W140 regulator swap. I think it could have tripped something out in the controls. Anyway going to see another mechanic that works with these kinds of issues and will post the solution. In the mean time, I still have to drive that darn BMW to keep cool. So sad. They never realized what true performance was.
 
#23 ·
Hey Eric. It's been a while since I've updated you to what has been going on. I have been quite busy and haven't had the time to even look into the car. Lately the weather has been cool so the A/C hasn't been an issue. But recently I decided to take it to a certified Mercedes benz repaid shop. I have never seen so many Mercedes in one place at the same time except the dealership. Immediately within 10 minutes he diagnosed my problem as the sun sensor. He said the sun sensor is reading the car at a lower temperature than it actually is and in effect shutting the compressor off because it thinks the inside of the car is way too cold. I confirmed this by reading the live data on the climate control system (holding rest for 5 seconds) and the first sensor reading I get is the sun sensor. The farthest right part of my display isn't working but it's just a couple of pieces that's not working but I can clearly see the sensor is reading 30 or so degrees. This makes total sense to me now. I have not enlisted him to fix it yet as he is asking for 275+ CA state tax brining it to 301 so I'm just shopping around to see if there is another shop that can do this. I will let you know after I get the problem fixed what the verdict is. Thank you for all your help Eric
 
#28 · (Edited)
The in car temp sensor is behind the dash and the sun sensor should be on the hood between the grills.


BIG EDIT, sorry I must fix my head tonight. In car temp sensor is behind the interior lamp at the top center of the windscreen. Sun sensor is on the hood at the rear near the windscreen amidst the two grilles and the evaporator sensor is inside the evaporator which is the big job and needs the dash to come out.

So you need to be sure which sensors he is talking about, the first two are a simply DIY but the evap sensor is a major job.
 
#31 ·
Correct on both counts, your sun sensor is on the dash instead of the hood for some reason, and the in car temp sensor is behind those little grills in the overhead lamp.

The in car temp sensor comes complete with a small fan which blows air from the cabin over the sensor.

Quite often the fan covers the sensor in dust and small debris which makes the sensor less sensitive, so sometimes just cleaning the mess out helps.
 
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