I have an 84 cutlass supreme, the blower motor works great except on high. I know its not the switch because I already replaced it but what would cause it not to work on high? Also how does the vacuum switch next to the distributor for the heater. Does it let the coolant flow through the heater core when it gets vacuum or is it when it doesn't get vacuum. Thank You for Your help in advance.

-Devan

 

Pretty sure the high speed for the fan is supplied power through a fusible link to the high blower relay. try tapping on the relay housing, maybe the relay is stuck? Check for power on the heavy gauge red wire. Most likely the relay has failed.

The heater control valve cuts off coolant flow through the heater core with the a/c selector switch in the max position. With the switch in max a/c, there should be vacuum on the hose leading to the control valve. Hope that helps

 

Ok I am sorry I should have said this before but my car was butchered before I got it there is no heater control valve on it. I am going to have to buy one, I don't know what condition my vacuum hoses are in under my dash. I am going to have to put a manual switch in my car under the dash or my hood. I will try to fix the vacuum lines so I can just use a factory setup but I don't know if that's possible. Like I said the wiring and vacuum was butchered.

My first situation is getting my high speed setting working. So my question is where is the fusible link route locate and routed from? Next question where is my relay located? Firewall?

 

It is usually one or two of the following:

1.) A bad fuse (on the firewall in a fuse holder) in the purple? (can someone confirm the wire color?) wire to the high speed relay on the right side cowl area near the fan motor. Not the wire to the fan, the wire to the relay,
2.) A bad relay,
3.) A bad switch and/or a burned plug and connectors at the fan switch.

I would start by checking for power to the purple wire at the relay. If there is no power, trace the wire back to the fuse and look for a bad fuse and burned fuse holder. If there is power at the purple wire, placing the fan switch on high and the key in the run position should make one of the wires to the relay energize. This is what closes the relay but I cannot recall the wire color.

If there is power to the relay and one of the wires get energized via the switch then voltage should go to the fan motor. If it does not the relay is bad.

If none of the wires get energized by putting the fan on high then look for a bad fan switch and a burned connector at the switch. The high speed circuit draws a lot of current and often burns connections. Even if the problem is the fuse, I recommend that the fan switch and the connectors be checked for reliability and to prevent a possible fire or smoke condition under the dash. The switch and connectors often melt due to excessive heat.

Hope this helps!!!

 

Dshelvy,

Sorry read your post again and saw you changed the switch. Was the connector at the switch melted at all?

About the fuse, I do not believe it is a fusible link, instead it is a regular wire with a fuse in an inline fuse holder.

The relay is on the right side on the top of the cowl/plenum area of the fan motor. It is held in place by two screws.

 

Okay thank you both I found a diagram (on G body forum) for the whole climate control system for my car I will try to put this info together and make it work tomorrow Thank you and I will let yall know and keep you posted

 

There was no constant hot wire from the battery. It is working great now other than it switching vents because of the vacuum lines not being correct. Does any one have a vacuum diagram and it doesn't have any vacuum hoses running to engine or anything under the hood.