2005 gmc sierra heater fan quit working. I lost the fifth speed months ago and a couple of days ago lost the other four, the first day the fan would come on sometimes while driving then quit after a while then come back on. Now it does nothing. I thought it might be the control since it lost the high speed awhile back.

Check fan relay.Turn heater and fan on turn ignition to on position then pull up on fan relay if does'nt click replace relay.

This is your blower motor regulator. It is under the glove box and behind the blower motor itself. They are cheap to purchase but a pain in the rear side to replace. Hope this can help you out sir.

fuel pump relay. ther 11.99. if thats not it check your fuel injectors. im 99.99% sure its your relay.

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1999 Tahoe HVAC Head Unit Replacement

Yes, the heater fan does have a fuse. If the fuse isn't blown, there's a sensor in the duct work behind the glove box under the dash that controls the fan speeds that you can check.

The resistor is most likely bad but should still work on the highest setting.Would check pigtails to the resistor and to the blower motor for burnt or discolored wiring.You can try tapping the blower motor and wiggling the wiring harness too see if it will work on the highest setting. It is possible that the blower motor is bad as well typically when you lose the speed selection it is the resistor but you should always have high speed.

lubricate the shaft. if no improvement, the motor is defective.

The problem is probably the blower motor resistor. I'm not sure where yours is located exactly. They can be on the firewall under the hood or some are near the blower motor under the dash.

THERMOSTAT REPLACE IF NOT SEE IF HOSES ARE CLOGGED SHOT OF AIR COULD HELP OR DISSCONNECT BATTERY CABLE 10-15 MIN CONNECT BACK TRY HEATER

replace the BLOWER MOTOR RESISTOR this will allow your low through high controls to work again.. as far as the squealing sound oil the fan or replace it
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