Heater fan not working - 2000 Pontiac Grand Prix

Does the switch works in other modes ( ac, def ) If not , ck power & ground at the fan itself in all modes., If OK R/R the fan. If the fan only loses power or ground in heater mode look toward the wiring------switch control. Good Luck.

Yes it's the heater relay. There is no power activating your relay
Replace it

It can be issue with relay or wiring of the fan causing the problem.
Check the help links.Click the link below:---
A/C, heater, defroster fan, not working? http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html

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Heater AC or defroster fan not working on KIA? http://technoanswers.blogspot.in/2012/02/heater-ac-or-defroster-fan-not-working.html

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Where is A/C CONDENSER FAN MOTOR RELAY Located? http://repairhelpcenter.blogspot.com/2011/11/where-is-ac-condenser-fan-motor-relay.html

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How to Remove Fan Clutch ?

http://technoanswers.blogspot.in/2012/04/how-to-remove-fan-clutch-on-2005-gmc.html

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This will help.
Thanks.

Most of the time when a heater blower quits working it is the blower switch that fails rather than the motor. Blower switch can be accessed in the dash panel.

Hello, pretty easy fix for this. replace the blower resistor assembly mounted under the passenger side of dash the resistor is held in place with 5.5 mm screws

your fan speed regulator located on your heater core box is bad if its just one or some of the speeds. if the fan does not work at all its either a bad connection to your fan speed regulator or the fan motor has quit. out

Have you checked the earth? You may find current is going to earth via the fans. Find the earth for the heater and make sure it is earthing really well. Hope this helps.

Hi: Sounds like a possible heater resistor problem. First check to see if heater fan working, unplug heater under hood and put 12 volts to it from the battery with a wire (single black wire running to back of fan). If works then problem probably the resistor which is located on the fan housing under the hood to the right of the fan. The resistor has wires to it running from the heater fan, 2 - 7mm screws holding resistor in place, check resistor to see if any of the 3 elements are melted off, if so replace. Note: Rear window defrost has nothing to do with heater fan. Hope this helps...

The heater core has gone out and will need to be replaced

You most likly need to replace the fan or possibly the fuse for the fan blew.