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Old 06-18-2013, 05:48 PM
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Join Date: Mar 2009
Location: San Diego
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Quote:
Originally Posted by brooklyn View Post
Hey Guys,

So my AC works well when the compressor decides to kick on, had it recharged last year. It only doesn't engage occasionally. I've noticed though that on long drives running AC car is fine, but in stop/go traffic the thing climbs to 110/115C. Hard to get it down even with heat blasting into the cabin.

Is my AC compressor bad? Is that causing the overheating issue? Otherwise for the most part the car runs 80C or 88C in summer.

I've also heard of folks hotwiring a switch to the aux fan in front of the rad. I would love to learn more about that if anyone has done it, what part did they use, etc.

thanks,
Do you know the Aux fan comes on at low speed when the A/C is on? Check the Rec/Dryer area. There are 2 switch sensors. One is low pressure switch to indicate freon is fully charged. One is a high pressure switch which activates the Aux fan at low speed. Jump the high pressure switch and the Aux fan should comes on. It not then the resister R14 may be busted. I am not sure where is it located in the W124, probably same as the W126, underneath the brake booster area.

It is easy to jump the Aux fan at high speed. Locate the temperature sensor on top of the radiator hose in the engine block. It is a 3-prongs sensor with 2 connectors - one 1 prong, one 2 prongs. Locate the 2 prongs connectors and short the 2 pins. The Aux fan would come on. Just install a switch there to simulate the sensor is making contact internally, or temperature is reached. It should make contact if the coolant reaches 100C or 105C, depending on the sensor part #.
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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.
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