Blower Motor High Speed

richamer1

Frequent Racer
Oct 17, 2004
524
0
16
New Carlisle, Oh
Fan works fine on all speeds except high. I would think that points to the fan switch inside the car and the resistor is fine. What do you think ?
 

malicad

Dragway Regular
Dec 8, 2009
1,383
0
0
South Milwaukee, WI
I had the same problem on my a/c equipped 79 coupe once. If I remember correctly, there is a resistor for each fan speed under a little cover near the top of the a/c unit. I replaced the resistor and it worked normally. You could probably test the resistance of them just to be sure. If I'm wrong, the resistors may just be used on the lower 2 speeds of the fans, to dissipate the extra current, then on "high", the whole thing is bypassed. But, again, I replaced mine, and all was good.
 

RatMalibu

Pro Stocker
May 21, 2003
2,225
0
0
Rolla, Mo.
www.fidnet.com
It's been a long time but as I recall there is a wire loom that comes from the drivers side firewall and runs behind the engine to the passengers side, somewhere around the passengers valve cover there is a connector (4 or 5 wires iirc) there is a large gauge (10-12) red (I think) wire in the connector...it's what actually runs high speed in the blower. The connector gets a little corrosion in it and then gets hot from the added resistance and will melt so it doesn't make contact anymore. I just removed the connector and spliced all the wires together, it's only there to join the HVAC stuff to the main harness so they could be assembled at different times imo

find the connector and check it while you are checking the resistor, switch, etc...it was the cause of my "no high speed blower"
 

LS6 Tommy

MalibuRacing Junkie
May 15, 2004
15,847
1
38
North Jersey
High speed does not use the resistors, it has a relay and a separate larger gauge, red feed wire. Like Rat said, there is a connector for the larger gauge red wire near the blower box that sometimes gets corroded and the circuit opens. It's a very common problem with GM cars from that decade.

Tommy
 

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