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Old 07-08-2012, 11:41 PM
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compu_85 compu_85 is offline
Cruisin on Electric Ave.
 
Join Date: May 2008
Location: La Conner, WA
Posts: 5,250
W126 AC / Aux Fan modification

Just pondering something here, would like input from the membership.

How my 91 350SDL was set up from the factory:

Dual pusher electric fans kick on to low speed with AC high side is over 250 PSI.
Fans kick on to high speed when coolant temp is over 110*C.

Simple mod I have done:
Temp sensor mounted on ABS unit turns the fans onto low speed when the receiver / dryer or engine bay is above ~90*C. It is wired in parallel with the AC high pressure switch.




The fans move a lot more air on high speed. I have an upgraded alternator, and the fans draw 16 amps on high so that won't be a problem.

I'm thinking of either doing:

A) High pressure switch or 110*C coolant temp kicks the fans onto high speed, engine bay / AC temp over 90*C kicks fans onto low.

B) High pressure switch kicks fans onto low. Engine bay / AC temp or coolant temp kick fans onto high.

I'm thinking of going with B, as I really only want the fans blasting away on hot hot days.

Any input?

Thanks,

-Jason
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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.
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