Red C4

Hi Guys, I have 1991 C4 auto Coupe with Automatic A/C system.
I have determined a bad connection at the 4 wire plug into the blower control module . It seems that for some reason the blower has run constantly and melted the Purple Wire in the square connector.

The blower had not been working at all . I bench tested the motor and it was fine. I managed to clean the connector enough to make contact at the Blower Control Module , but the blower won't shut off, even with the ignition turned off.

Does anyone have a suggestion what I should check next ?

Thanks
Graham

Red C4

and the fan only runs on a high speed. It won't slow down when I try to adjust the fan speed from 10 down to 2 or 3 .

mtwoolford

Sounds similiar to an issue I had with a 96; especially the melted wire part (can't remember the color)

First question: Is the blower motor speed controlled by a series of resistors mounted down in the plenum (typical GM) for three (or thereabouts) fan speeds ? or, is it a ciruit board mounted on aluminum heat sink (giving 10 or so fan speeds) as my 96 ?

mtwoolford

As I re-read your posts, yours is probably the later. Mine required replacement of the fan control module; a very expensive part, $300 list, found one new for $200, went to a pick and pull, found the same module (plus the plug and a foot or so of the wiring harness) out of a full size, 90's GM sedan (Caddy as I recall) ; mounted it onto the Corvette heat sink (the Caddy heat sink was too large to fit in the corvette ductwork), connected / spliced the wires into the Corvette harness (just followed the colors or the placement in the plug/connector) , there was one extra wire, taped that off, all functions, all ten speeds restored. Probably the only $20 repair I ever did on the car.

Red C4

Thanks very much for that. I have the C68 (I Think) climate control which is 10 speeds. I can find the resistor available locally for the manual systems but not the module required for the Climate Control system. Eckler's has and aftermarket one for $ 169.00 . It will likely cost me another 100 bucks for shipping brokerage and duty to get one here from Florida. Used would be good ! Thanks !!

Tx_94vette

Exact same issue on my 94 right now, noticed heater wasn't blowing warm only cold, pulled plug at the air mix area and purple wire has melted connector, fan works fine if I refit burn`t connector, air mix door is continuously oscillating though, maybe we can just need to fix connector and pull the plug from the mixer for now, not trying to steal tread just trying to shed some light