auxillary fan runs

[joel price]

all the time on my 84 190D--temps is normal--AC has become very erratic about coming on when I push the selector button---Could these be related? What causes the auxillary fan to run all the time?
Is it a selector button problem that would cause the AC to be so erratic about coming on? If I leave the AC on when I shut the engine off and come back and start it the AC may or may not come on.
I appreciate any incite into the problem --it's still hot in Atlanta
Joel

[RAYMOND485]

1984 300d Turbo 140,000
Replace The Aux Fan And Compressor Relay On The 300d They Are
On The Driver Front Engine Side Fender Both Are Same Ice Cube
Relays 5 Pin Pull Out May Have Cover On Top

[NateVentura]

Joel,
Not sure if this applies to your engine or not: I also had my aux-fan stuck on all the time (300SD, 617), and it turned out to be a failed thermal switch (the one near the thermostat). It had failed in the closed (i.e. grounded) position. When I pulled the connector on the switch, the fan stopped. I replaced the switch, which fixed the problem. YMMV - I didn't have any other AC funnies going on. Hope this helps...

[ne2i]

Hi
Does that evacuate your AC freon when you remove the switch?
I have a fan that wont come on....
Also where is the relay for the fan on an 81 300D sedan?
I want to hit it with some contact cleaner before i replace it....


George

[NateVentura]

"Does that evacuate your AC freon when you remove the switch?"

No - it's a coolant temp sensor.

[Grdenko]

yo
my aux fan runs all the time too during the summer, even when coolant temp is below 80C. I think the aux fan will run all the time if the outside temp is over 90 or 95 degrees F.