1990 pontiac Bonneville heater problem..

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:

Probably the way it was designed to work.

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 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:

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