I put the dash back together in my 69 Cutlass and got the three lower speed settings to work but the high speed does not. Is the high speed on a different circut or is the switch in the dash bad for just that speed? I dont know if it worked before because everything was apart when I bought it. Any suggestions?

 

Check the wireing under hood at the relay ,I have also replaced alot of those relays

 

I agree with ozone, but to check for a bad switch, find the positive and connect it with the negative for the high spped and if it dosen't work, it is a problem elsewhere. also, if you can get a meter, check for a bad conection, relay or wire. you can get a meter at canadian tire or walmart for 5 bucks, if the leads arnt long enouh, solder on some more wire.

Good luck finding your problem

 

Thanks for the information. I will double check everything but the relay did look good to me. All the connections needed to be cleaned at the relay just to get it working. I am not even sure if that relay is still available. I'll let you know what I find. Thanks.

 

Believe it or not, there is a resistor block mounted in the air plenum which controls the fan speed. It is located on the firewall side in the engine compartment. Look for a wiring harness with three or maybe four wires connected to a plug that is screwed into the air plenum with two screws. The device is oval shaped about two inches wide and an inch high. Carefully unplug the harness and then remove the screws. When you take the device out you will see three coils of wire, each one a differnt gauge. I bet the smallest gauge wire is burned through or broken at the connnector. This is the one that controls the high speed, it may not even be a coil but a straight wire. These things heat up when currrent passes through them on the way to the fan motor, by offering resistance to the current in the fan circuit they determine the speed of the fan. They are mounted in the air pleanum to keep them cool. It works great because the higher the fan speed the greater the current because the resistance is less and the wire heats up more, but since the fan is on higher the air moves faster and keeps the wire cool. Neat design. Anyway, your best bet is to go to a junk yard and find a replacement from a similar GM car. They are almost all the same with slight variations.