recently noticed temp guage rising while at standstill, after checking discovered aux cooling fans not kicking in until temp just under 120 then kick in full speed and shut off around 105 or so. I know the fans are supposed to be running at lower speeds and kicking in at lower engine temp, esp whenever ac is on. ac is working fine and seems to be fully charged. No high engine temp problems going down the road, just while sitting stationary with engine running.

Please need help diagnosing/locating faulty part (relay?/switch?/etc?). Thanks!

 

the fan has resistor for lower speed. I think back then they had a relay with fuse on them for low and high speed but not sure.

 

There are two relays (small 1" square ones) at the back of the fuse box. One is for the high speed fan operation the other low speed.

Your low speed relay is bad. If you switch the relays you should get the opposite result, no high speed fans.

 

I have a 88' 300E and my a/c is blowing hard but not cold air. Heat works fine .cooling Fans not coming on at any temp either. What might I need to check or replace

 

Check freon level

 

@ attila , fan not blowing @ any temp. Checked fluid levels and the resevoir was mt
I see why the sensor that plugs in the buttom was leakin. There is no lock clip inside there
, ordered a new one. Should be here in a few days then I will post on here an update.