Question about 1998 GMC Sierra

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1998 GMC Sierra pickup truck cabin fan problem

Fan only works on HIGH. For example with the air conditioner turned on I am either freezing or hot. No low speed working, just HIGH of off.

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  • 1mikie Dec 01, 2008

    where is the resistor under the dash or under the hood thank you

  • jim3426 Feb 06, 2009

    My fan works somtimes, but only on High. I have to turn it off and on 50 times bfore I get anything. I replaced the resistor under the dash (not that)

    What else could it be

  • Anonymous Feb 18, 2009

    I have the same problem. My blower works when it wants to and usually when it is comfortable outside.

  • generallee69 Mar 26, 2009

    I now have the same problem. I have a 98 GMC Sierra K2500. Found water in the blower motor housing. Blower motor is shot (will NOT spin when hooked straight to a battery). Replaced blower motor and only works on high. Replaced the resistor and still only works on high. Could this be the actual switch now or is there something else I need to look into?

  • Anonymous Mar 15, 2014

    the fan motor on my 2006 gmc truck works on all speeds part of the time but not all the time.it has been doing this for awhile now it has quit completely

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Your blower moter is under your glovebox and very easy to replace.I dont think thats your ploblem.I would pull off the dash.It will snap right off without breaking anything.Then pull out the part that holds the selector switch for the fan speed.Then you unplug that switch.Clean the copper contacts.Plug it back in.If everything works again like it should and did in my truck then it is either that switch that is bad or the wiring harness.I would replace that switch.

Posted on Apr 01, 2009

  • Cameron Walker Dec 21, 2010

    This cleaning of the fan speed selector plug in solved my problem. The vehicle is 98 GMC Sierra. I stopped getting any fan action. I followed Gixxer386's instructions above--success! -unclip dash, unclip heater control panel from hole in dash, unplug wire harness going to fan speed selector switch. One of the 5 copper prongs looked dark, tarnished. I sanded and blew the plug clean and now the thing works. I can't find the blower speed resistor. Where the heck is it? "By the heater plenum" means nothing to me. I found a relay behind the glovebox and it was clean looking. I didn't replace it because i got the fan working already.

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The most common solution is to replace the blower speed resistor. The blower speed switch is probably not to blame here because you state that the blower either works on high or is off. Is the blower blowing high on all speed settings, or is it off until you reach the highest setting? In either case, the blower speed resistor is less expensive than the diagnostics, and once you install it the diagnostics are done! If it doesn't work after you replace the blower speed resistor, the the blower speed switch or the wiring is at fault. In my experience this complaint is solved by the blower speed resistor 9 out of ten times.

Posted on Nov 01, 2008

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Have the blower motor resistor checked, a faulty one would usually cause that problem

Posted on Nov 01, 2008

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Blower motor has ice in it and started to burn up . I need to know how to pull it out?

Posted on Dec 13, 2008

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