I think I have read every aux fan thread, but I have a slightly different question. My low and high speed fans work and come on appropriately - but what turns off the low speed fans?

It has been hot here and if I turn on the A/C the low speed pressure circuit kicks in pretty quickly - but if I turn the A/C off the fans stay on. If I shut the car off and then just turn the key on, the fans start running again. It is not the high speed - car wasn't close to 105-107 C and fans were clearly running at the low speed.

Any ideas?

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Next time it does it, dissconnect the wires at the drier sw with the pigtail leads.

Report that finding.

Also , it takes a little time for the high side pressure to drop, so give me a time frame.

__________________
A Dalton

Are the fans supposed to always run on low speed when using the A/C? I'm not sure if they do on my 300E.....the A/C is cold and it does not run hot though. The electric fans do come on if it was turned off and the temp rose while it sits for a while and you start it back up. They ran on high until it dropped to around 90C then they power down....

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Sorry for the delay in replying - I have been busy with some other things. I did some more testing tonight per Arthur's suggestions and when I disconnect the pigtail, the fans turn off. Tonight, after driving around town for a while with the A/C on, the fan ran for at least 30 minutes after turning the A/C off. I let the car run for a while, I left it with key on, I turned it off and then turned key on after a minutes - and the fans kept running (they didn't run while the car was off).

I'm beginning to think this is connected to my other electrical issues - see the following thread:

http://www.peachparts.com/shopforum/showthread.php?t=255267

I have been monitoring the voltage put out while driving, idling, etc for a few days now - after having replaced my voltage regulator. It's a little better, but not above 14 volts - except maybe on a cool day with all accessories turned off. My central locks still do not work, and the convenience system works sporadically.

Any help would be appreciated.

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Suspect is the pigtail wire/high side pressure switch...

__________________
A Dalton

Can I replace without having to evac the A/C system?

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

No..it requires evac , unfortunately........

...but you can put a toggle sw in the cabin and use it when you use the a/c.

Correct remedy is to change the sw., but may guys have a toggle already hooked to that sw anyway for a manual fan circuit over-ride modification [for towing and traffic jambs,] so they get used to it.

Might want to put gauges on the system and an ohm meter across the sw to check it's cut-in/cut-out specs.

http://catalog.peachparts.com/ShopByVehicle.epc?q=1991-Mercedes--Benz-300ce-Climate--Control&yearid=1991%40%401991&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6175%3AMBC%7C1498%3AED%7C10000018%40%40300CE&catid=242213%40%40Climate+Control&subcatid=242240@@A%2FC+Temp%2E+Switch&mode=PA

__________________
A Dalton