I have a 1970 Cutlass Supreme. The other day I had the a/c recharged by a "professional". While driving home the a/c was working good. Then stopped. I noticed the compressor was not engaged. I also noticed that the power supply to the compressor was not connected. Must have fallen off, for that it wasn't put on properly. Now everything seems to be working, but the high speed for the blower is not. A Three lower speeds work fine. When I take the hot wire off the relay (on the firewall) and bypass it to the plug feeding the blower, full speed of the blower is noticed. This is with the ignition in the run position and the blower switch on high. I replaced the relay. No change. No fuse issues either. I am thinking that it may be the switch itself. Before I start laying on my back, and removing duct work to get to the switch, I thought it to be wise to ask others. Thanks! Gary

 

I am aware that you checked fuses. But did you check the inline one?

Pat

 

This link should help:
https://classicoldsmobile.com/forums...work-high.html

 

Thanks for the help with the location of the fuse . I will check it out. I thought that was the holder but it looked odd. I didn't go any further because I had voltage to the relay. It would be nice if this is the issue. Thanks!!!!

 

Look at the schematic.

Troubleshoot it logically.

If you have voltage at the relay connector from the wire that goes to the horn relay, then, obviously, that fuse is good.

If you have the lower three speeds, then, obviously, the other fuse is good.

If the relay pulls in and makes the blower blow on High when you energize the coil, and the lower three speeds work as well, then obviously the relay is good.

That would leave you with the wires and connectors between the switch and the relay and the switch itself.

One step at a time. Process of elimination. Test the easy things first.

- Eric

 

I have the same issue with my SX. Thanks to this post I was able to fine the problem. The fuse was indeed bad. In looking for a replacement, I see there are high and low amp fuses, can someone let me know which I should use as a replacement. Thanks for the tip and help.


Don

 

The fuses should be rated by current, such as 15A, 20A, etc.
The owners manual will show what amperage it should be. I can check when I get home from work if no one has posted by then, but just from memory I think it's 30A.

 

Thank you for you help, it is 30A. I'll replace the fuse this weekend.

 

Hopefully it blew the fuse before it took out the high blower relay, which costs more than a fuse.

 

Yes! Fuse fixed the problem. Thanks all.

 

You're welcome.