Possible fan ignition switch symtom?

[gpgt98]

I have had some symtoms that have been atributed to the fan switch resistor, and/or fan ignition switch harness. Mainly the fan don't work on settings 1-4 but will on 5, also the headlights ( DTRL'S ) go out when 1-4 is selected. More recently the selector switch for A/C to heater felt like i was going to break it to move it from A/C to the defrost position. Is there any relation to the other symtoms? 98 grand prix GT 3.8L
72,000 miles. Single climate control.

[BNaylor]

It is possible but the only way you'll know for sure is to replace the HVAC head unit which may not resolve your problem. Your problem sounds consistent with a bad ignition switch.

[nathanadams]

I have a 98 GP 3.8 with the same problem except that my selectors turn fine. I have tried replacing both the resistor and blower motor today with no change. All my fuses are good. How could this be related to the ignition switch??

[gpgt98]

Trust me , it most likely is the ignition switch harness. I am NOT a mechanic. I can tell you that I did replace the ignition harness and it did take care of the problem that is atributed to the resistor. I had changed the resistor 1st also but it did nothing . The REAL car guys like bnaylor or richtaz may be able to tell you why that part has anything to do with the problems you are having. If you follow the directions from big-L in this post : http://www.automotiveforums.com/vbul...d.php?t=271705 it is rather easy. Just be sure you have ALL the tools that is mentioned or you will run into problems. Like I said I am not a mechanic but with the help from the real mechanics here they make it pretty easy if you have the right tools ! DO NOT reply to that post! ( dont make the same mistake I did ) :-)

[BNaylor]

Originally Posted by nathanadams

I have a 98 GP 3.8 with the same problem except that my selectors turn fine. I have tried replacing both the resistor and blower motor today with no change. All my fuses are good. How could this be related to the ignition switch??

Based on gpgt98's symptoms we concluded it was a defective ignition switch and harness assembly. His symptoms were classic.

The correct way to determine if the ignition switch is bad is to apply proper troubleshooting techniques applicable to the electrical circuits by using test equipment such as a digital multimeter and using wiring diagrams from the GM Factory Service manual (FSM).

The ignition switch provides the 12 volts needed by the climate control unit to operate the blower motor. You can check fuses visually but that doesn't mean the 12 volts is present at the fuse socket when ignition is ON. So a multimeter will come in handy by selectively checking key points in the applicable circuits to determine which part to include wiring is causing the problem.

The best thing to do is post what specific problem you are having with the HVAC system in detail along with all known symptoms. Also, what parts were replaced. Identify the original problem you were having before you started replacing parts. For example what blower speeds were missing?