Blower Relay Question

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Bradster941, Jun 29, 2013.

  1. Bradster941

    Bradster941 New Member

    Greetings all. I used the search function but did not find the answer to my question so perhaps someone here can help. I have a 1999 2500 Silverado 4x4 . According to Auto Zone for this year and make, there is a blower relay in addition to the speed control resistor but I have not been able to locate it. I checked behind the glove box but saw nothing. The fuse/relay panel under the hood has a A/C relay but I assume that is for the compressor. I lost speeds 1 thru 4 but still had 5 (High) until recently. Now I intermittently have high. So logically it would seem I may have both a bad Resistor and a bad relay. The wiring harness is fine and not melted. Blower works fine when it is getting power. Any idea where this relay is located or is it part of the resistor assembly? The resistor seems to Ohm out o.k.. Thanks so much.

    Attached Files:

  2. j cat

    j cat Epic Member 5+ Years 1000 Posts

    This relay/resistor component is in the air box where the blower motor is mounted. you will see the connector only until you drop the assy from the air box. I would drop motor and make sure it has clean clean. then replace the air filters which should be used in this vehicle.

    the GM resistor assy which you have a picture of here is defective in design . the assy does not have proper protections from the air ingested elements.
  3. Bradster941

    Bradster941 New Member

    Thank you Sir. Just to confirm then, this is both the resistor and relay then?
  4. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    @j cat is correct, there is an internal relay inside the speed control module (if you have the manual speed control HVAC unit); but, you should still find a couple of external AC relays. There should be one for the clutch inside the compressor and at least one other relay used by the HVAC unit. Both of these should be mounted on the under-hood fuse panel.
    Last edited: Jun 30, 2013
  5. Bradster941

    Bradster941 New Member

    Thank you Gentlemen. Update. New part is in and everything is A-O-K.... :happy:
  6. j cat

    j cat Epic Member 5+ Years 1000 Posts

    yes this is both a resistor to give you lower speeds. the relay is for the max speed. it is not recommended to operate this blower motor at the max speed for a long time as this will cause failure. as I stated before make sure the air box/blower is clean. replace the internal air box filters next to the resistor assy down stream from the resistor. there are two white filters side by side. if the air flow is restricted this causes resistors to overheat .

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