Mercedes E320 2002 169K- AC clutch does not engage

Chaud

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#1
AC worked fine yesterday but today only hot air. looking at compressor I see clutch not engaging. Ruling out low level of R134 what else can go wrong. How can I diagnose to get to the problem area? As always I appreciate your help.
Thanks-Chaud
 

billr

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#2
How are you ruling out pressure, did you use gauges on it?
 

nickb2

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#3
Hi, you can bypass the ac clutch relay, even with low or no freon, the clutch will engage if all electrical is sound. If it does not engage whilst directly bi-passed, you need to check elsewhere.

If all pressures look good and electrical is good, may need to replace the clutch, this is costly on these models. Need alot of special tools. my $.02

If the clutch does not engage, hmmm, will need you to do more research and post back details of what you have found. :thx
 

Chaud

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#4
Billr: I could be wrong in my assumption because the day before it was blowing pretty cold air. But this possibility of lack of gas is still under consideration.

nickb2: I was thinking of by passing the relay but I can't find that relay in the regular fuse box. They are all fuses. It could be under the dash but not knowing which one makes me come up with a plan b. That is supply 12V directly to clutch coil. Once the clutch engages, I will run for 5min. or so and then get into auto-climate control computer diagnostic mode and read all the sensors values including low side pressure. Right now I went into this mode and see error code E61419 ( believe it is for bad clutch ) but this could be for many other reasons which I am trying to find out. Any other option or idea please let me know. i will post results as soon as i get them. Thanks-Chaud
 

billr

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#5
Did you measure resistance of the clutch coil? That may save you the bother of running a wire over there to provide 12V direct.
 

Chaud

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#8
It was a very simple fix. 12V single wire which goes to clutch was broken near the field connector. It was somewhat harder to get this connector unhooked so I decided to leave it alone and solder the broken ends of wire together as is. Once wires soldered AC works great. Now the question is how this wire got severed? There was no stress on the wire as for as I could see. But I will leave this mystery for another time.
I like to thank you all for your help and great ideas. Chaud
 

nickb2

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#9
Hi, I am happy you didn't have to replace that compressor, it cost's a fortune and not much fun to replace.

I know this is not a merc I am going to write about, but I was working at chrysler up in quebec city, would see this all the time on neon's and other model's.

BTW, did ever find that relay? :thx
 

Chaud

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#10
I did not find the relay in engine compartment. I thought before I go for the hunt, I should first find out if 12V present on the clutch wire when AC on. I just lucked out and search ended there. May be this relay is tucked under the dash somewhere.
Chaud