Problems started when Aux.fan would not come on with AC. I checked connections and now it seems I have no power to climate control unit. Checked fuse #11 for ac and blower. Is there a inline fuse or something simple I am missing? The Aux.fan will work if I ground the wire at thermostat. This is a 85 Calif. 300SD.

I am not familiar with the electrical as far as the AC is concerned, but I'm sure someone will chime in shortly.

You probably need to check your refrigerant charge with a set of good gauges & post the results here. A low charge will keep the fan from coming on.

There are 2 switches, one on the dryer & another near/at the thermostat housing that turns the fan(s) on & off. They are screw-in. One or both might be bad or have a connection problem.

__________________
1987 300DT
2002 Ford F-250 7.3 Crew Cab Short Bed

Some cars of that vintage were retrofitted with a 30amp strip fuse similar to the 80amp glow plug fuse. It's usually in a separate case within a handspan of the main fuse box. IIRC it's only for the blower.

Sixto
87 300D

There are times that even if the fuse is good, there is no continuity. I would suggest to try to remove the fuse and clean the slot and the pins that holds the fuse, and scotch brite the 2 ends of the fuse as well.

__________________
'85 300D Turbo - CA Version

Thanks for the replies. DagObx you maybe right about the switches, the one for the Aux.fan I think is bad because I can ground it and it will work, but why won't the blower fan work even trying the heater.

Yesterday I removed the blower fan, cleaned,oiled and checked to make sure it worked. The AC and blower were working great till I started checking and poking around to get the Aux.fan to work.

Will do more digging into fuse box and remove and clean fuses.

Does the 85 SD have a two speed aux fan with the lower speed triggered by the AC pressure switch? If so, maybe the problem with the aux fan is with a burned or corroded low speed resistor.

Have you confirmed whether it's only the blower fan that doesn't work or the ACC quite completely? You can check by pressing mode buttons and listening for the actuators to move, or set the temperature wheel to a min and check for continuous ground to the monovalve.

If only the blower doesn't work, did you note any axial play in the motor shaft? This indicates worn bearings. Even a little play can set the brushes away from their contacts. It doesn't help that the blower shaft is vertical. Sometimes setting the blower to max or kicking the blower housing gets the blower started. If so, your blower need more work than cleaning and lubing.

Sixto
87 300D

If you do have to replace blower, etc., I did a write up on how to do it.