What would cause the heater fan to run constantly in a 1990 Pontiac
Bonneville.The only way to stop the fan is to pull the fuse.A friend had
a back yard mechanic work on the car because it would not start.He said
he had to repair the ground strap and now the heater fan will not shut
off. He said he replaced a fan relay with no success.He also offered to
buy the car from her for $800.00 .This is her spare auto but is in
really good condition..Any one know what the problem might be..TIA..Jimmy

It is most likely the blower motor controller. I have the same problem
with my 92 Bonneville. The controller is located under the
maxifuse/relay bank which is under the hood on the firewall. Remove the
maxifuse/relay bank and then remove the three 7MM screws that hold it
in. It is a large semiconductor controller mounted on a 4 inch
aluminum finned heat sink that is lowered into the stream of air that
passes through the heater plenum.

The salvage yard didn't have one and told me the cost at GM is $400 . .
!!!

I am trying to find one on-line as we speak. If you need pictures I
have them . . .

Bob

James DeBord wrote:

"James DeBord" <jedbord (AT) erols (DOT) com> wrote

"James DeBord" <jedbord (AT) erols (DOT) com> wrote

Is it an SSE? The SSE model's had electronic climate controls. If that is
the case, there could be something wrong with the controller box itself. By
the way, if the car is in good shape with no other mechanical problems, and
has low miles, don't sell it for $800. Those cars last forever, as long as
you take care of them.

Hay thanks guys,I appreciate your help..I`ll look at these parts and
post results..Jimmy

James DeBord wrote:

Hay Guys,My friend called me today and asked me to thank you for your
advice..The controller box was replaced and the fan is now working as it
should..Jimmy



tsemi wrote:

"Captain Midnight" <Notany (AT) twip (DOT) invalid> wrote

From the OPs post on the 15th, that's obvious not the case.