Just recently had the AC system upgraded to R134 and the air is nice and cold again.
Now I'm having a problem where the AC fan doesn't come on all the time. I can hear the compressor kicking on when I set the CC unit to and AC button but the fan doesn't blow.
Then I'll turn the car off and back on and the fan works fine for a couple of days.

Could this be the due to the CC head unit? It has had intermittent issues with sticking buttons.

Thanks

Sounds like an intermittent connection or ground problem especially since it works for a while.

Might take a while to trace. When it happens, have someone turn the a/c on while you hold on to the fan relays, can you feel the click? (possibble stuck relay).
If they don't click on, check for power to the relay and you can check their operation by manually grounding them.

Stuck buttons, possibily but if the clutch is coming on, you're getting the signal from the ECM.

I'd check the relay(s) first.

I'll check that but I need a little more help please. I just moved and my FSM is in a box somewhere. Where are the fan realys located and if you have a picture that would be great.

Thanks for the info.

Driver's side radiator shroud, 2 of them side by side.

Quote:
Compressor clutch control and blower fan control are by the blower control module (BCM ) located in the top of A/c housing in engine bay.
BCM is basically a electronic relay controlled by the head unit

[IMG]http://i171.photobucket.com/albums/u309/vetteoz/electrical/BCM.jpg[/IMG]


Different years have different connections to / though the ECM but effectively the BCM grounds the power wire from compressor clutch to turn it on and also switches the power ( variable ) to the blower motor

Typical setup showing clutch control
(Sorry don't have a scan of the blower control side)

[IMG]http://i171.photobucket.com/albums/u309/vetteoz/electrical/BCMC68-1.jpg[/IMG]

Thanks for all the help and info guys. I'll look deeper into it over the weekend but right now the fan started working perfectly again.
thanks again