r66stingray

I am searching for a solution to an a/c issue on a 71 automatic small block.
When I first got the car it all worked fine. Now turning on the a/c from the off position I can hear the compressor engage, but the fan/blower does not work. Not on any of the speeds. If I position the fan switch to high and lower the dial to near defrost the fan/blower starts and I can raise the contol to a/c and the system cools on high fan speed. but the fan switch only works on high. lowering the fan speed shuts off the blower.
I have replaced the a/c heater contol unit in the console, replaced the fan switch attached to the control unit, replaced the heater resistors mounted in the firewall, with no luck. Fuses look ok as well.
Car has a small vacuum leak at the headlight actuator, but it does not impact the operation of the headlights or wiper door. not sure if they can be related, but the leak was there before the a/c issue started.

Any ideas are appreciated.

Thanks
Steve

TimAT

Sounds like one of the leaf style switchs in the control head is out of adjustment for some reason. At least for the basic running in the a/c mode. THe fan not running anywhere but on HI sounds like the resistor, but you stated that had been replaced. Time to get out the wiring diagram and start chasing wires. Is there a connector somewhere in the feed to the HVAC that might be a problem?

r66stingray

TimAT

Appreciate your thoughts. Going through the AIM wiring diagrams now

Steve

mark6669

Sounds like the heat/ac fuse in the kick panel box could be rusty connections check with a volt meter. high speed has a separate fuse.
Mark

r66stingray

Mark,

Thanks for the lead on the separate fuse. I will check it out

Steve