High speed fan question
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
I'm thinking it's the selector switch. Without an volt-ohmmeter and your car, it's kind of hard to say. I lean towards the switch because usually when a motor fails, it fails in all speeds. Have you also checked all of the other things that can effect fan performance, like a plugged evaporator, or debris in the fan wheel?
Drifting
Joined: Apr 2005
Posts: 1,323
Likes: 3
From: I KNOW JESUS... HE'S MY GARDENER
Mine does the same thing. Intermittent problem. I'm guessing the switch. Try unplugging the switch and bypassing with jumper wires to see if you can get the fan to blow high.
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
I would start with the high speed fan relay, these were a problem on most GM vehicles. I am not sure if the 75 has one or not, I think it does. Try wiggling the plug connecting to the fan relay. I have taken many of these relays apart and filed the high speed contacts to make them work but it is only a temporary fix. They are cheap at any auto parts store. It should be mounted on the firewall above the ac coil box.
Neal
Neal
Burning Brakes
Joined: Feb 2004
Posts: 958
Likes: 1
From: In the Beautiful Shenandoah Valley of VA
Hi blower speed is powered by a separate in-line fuse, 20 amp, I believe. Memory fails me as to exactly where it is at the moment, but check the wiring harness in the area of the blower housing duct work under the hood and see if you can find a separate orange wire. You should find a pull apart standard in-line fuse holder. Open 'er up and check the fuse. It's the most frequent cause of this failure.
Steve
Steve
