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Pontiac Grand Prix Heater blower relay switch



  • I paid $30 at the wrecking yard here in Phoenix 2 years ago or so.
  • My blower would run periodically. More so in cooler temperatures. I researched the fix, and checked the components. Replaced the fuse, only because it cracked it when I removed it to check it.

    I am an engineer coming from the compressor / blower industry. If the inlet air pressure is to low it creates a higher pressure differential and power requirement. Because the blower works off the resistor and at lower speeds and lower inlet pressures the resistor won't activate the blower. Eventually it won't work all together. The only thing that could create lower inlet pressures in a clogged filter. There is a cabin filter at the inlet to the blower. It is located below the windshields passenger side wiper. Raise the hood. There is a piece of plastic held on by two push pin holders. Lift the center portion of those holddowns up and it will allow the pin to be removed. Slide the plastic cover back to expose the filter. Mine was changed about 8-9 years ago. Something you just don't think about... It was clogged with dirt, sand, dust, and small leaves. I cleaned it by tapping it flat on a hard surface, then vacuumed it out. Looked ok, so I didn't get a new one. Replaced the old filter and my blower is working fine. This may work for you, before you spend the time and money.
  • Just_Me1970Just_Me1970 Huntsville, ALPosts: 5
    I have a 1998 Pontiac Grand Prix. I just fixed the seal under the windshield cowl to stop my floorboard from leaking on the passenger side. Now on to the problem, my fan blower motor. It works on all 5 settings, but, only on 1 thru 4 can i turn it up and down and off. Speed 5, however, will continue to blow no matter where i turn the dial until i turn it to the off position and disconnect the battery terminal and reconnect. What is my issue? I hear of alot of you guys 1 thru 4 not working, just 5. Not my problem. Seems to be different issue. Does anyone know what my problem is? Resistor? Blower motor? What? Help.
  • Just_Me1970Just_Me1970 Huntsville, ALPosts: 5
    My other issue was a funny one, but an easy fix. 1998 GP be driving down the road and it would cut out for a second and the rpm gauge would stop working and the traction control would go off and could not be turned back on. It was the crankshaft sensor. New one, now no prob. weird how this thing seems to be
  • Just_Me1970Just_Me1970 Huntsville, ALPosts: 5
    1998 GP. My lights work, rear defogger, everything. But my fan speeds only work 1-4 where i can go up or down or off. On 5, i have to turn it to the off position, turn off the car, and disconnect the battery terminal for a second to get it to turn off. Dont seem to hear anyone else having this exact issue. I know it all started when that seal under the windhshield cowl fell off and was leaking water into the passenger floorboard. Got that fixed. Easy. Just be sure to really glue it on so it doesnt fall off again. Could this just simply be the heater blower resistor? Im not good with electrical issues.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 22,961
    edited November 2018
    The manual systems often have a relay that connects the power for the lower blower speeds to a low supply line and lets the resistors vary the current to change the blower speed. Then when you switch to the highest speed, the relay is flipped and disconnects the lower power line and connects the 30 amp line directly from the battery to the blower motor. This bypasses the switch and reduces power loss.

    You might try tapping the relay when you turn the ignition key off. The contacts can burn and stick which could explain your problem. I do not believe there's another relay you can switch with that one to test by replacement. Most of the other relays are single pole single throw: on, off. That one switches two different power lines.

    I'll post a circuit diagram when I can finagle one.

    This should be close enough to help. It's a 2005 Grand Prix with manual blower controls.

    Removing fuse #53 will eliminate power to the 30 amp line. If you can move the selector in the dash to the high speed and then have it drop back to the lower speeds, you can drive it that way until you further troubleshoot the relay #13.

    Note the relay has to be in place for the power to go through it from the dark blue wire from the blower resistor pack to the purple wire that feeds the blower motor its power.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 22,961
    Here's the correct diagram for your 1998 Grand Prix.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 22,961
    I suspect you can take the cover off the relay. But use care. You'll likely find the part that moves when the engage low amp circuit enegizes the magnet is sticking to the contact.

    I saw a 5 connection relay on rockauto which is likely the replacement for your part. But it is
    not labelled as such. You'd have to compare the positions of the 5 wires to be sure it was a replacement.

    I suspect a junkyard pull is the easiest and cheapest replacement. since many similar GPs with manual controls would share the same relay.

    If worse came to worse, you could put a short wire stub with blade ends pressed on into the two contacts for the relay in normal mode to pass power from the speed resistors to the blower motor.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

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