No power to resistor for blower motor

Tiny
INDIANAWMN7798
  • MEMBER
  • 2002 PONTIAC GRAND PRIX
  • RWD
  • AUTOMATIC
I have a 2002 Pontiac Grand Prix. It has not had any heat or A/C for the past year. I have replaced the following in this order:

*Checked and replaced all fuses related to HVAC system (checked each before and after with test light)
*Replaced ignition switch (tested with multimeter, has continuity)
*Replaced control unit (head unit) (tested with multimeter, has continuity)
*Replaced blower (jumped with battery, works)
*Replaced resistor (tested with multimeter, has continuity)

After replacing these parts, I still have no heat or A/C. I have gone through with a test light and tested all power and connections. Everything is good until I get to the connector that attaches to the resistor. There is an orange wire to the far left of the connector that when I touch it with the test light, it has power. I check all the other wires in the connector, I get nothing. Even when I change the fan speeds on the head unit and use the test light on the connector, I get nothing. Just power to the orange wire on the far left side of the resistor connector. I have also jumped the blower motor and it works just fine, no problems. Even used a multimeter (or a volt tester) to make sure everything gets power and everything tests fine. Just get absolutely no power to any fan speeds on the resistor connector. The connector has 7 female slots (I hope I explained that correctly) and the car has dual climate control. I know the head unit has power, it turns the actuator door when you change where the air is blowing (floor, windows, etc) and when you switch from heat to a/c you can hear the door turn. The rear defrost works as well, which is the only thing that works as far as any defrost or heat is concerned. My mechanic has checked the thermostat as well as flushed my coolant system so there are no leaks and it doesn't and has not ever overheated since I have had it.

I have searched and searched for diagrams or how-tos on how to replace the wiring harness for the resistor or even how to replace the connector and have come up with nothing. I am hoping for some insight as to what I could do next. My next step is to test each wire coming out of the wiring harness without the connector attached to see if it is a faulty connector. But I wanted to make sure first before taking that step.

If you need any other information please let me know.
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Sunday, November 8th, 2015 AT 7:29 PM

10 Replies

Tiny
ASEMASTER6371
  • EXPERT
Ok, if you have power to the orange wire at the resistor, then there should be power to the one side of the blower motor. It is a ground control circuit. Thats why you donr see any voltage with your meter and test light.
Check the diagram I sent you and be sure both fuses are good.

Roy
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Sunday, November 8th, 2015 AT 8:21 PM
Tiny
INDIANAWMN7798
  • MEMBER
I will definitely check both of those fuses when I get up in the morning with both my test light and fuse tester. I am sure I checked them both but will do so again. My mechanic had also suggested it was possibly the head unit but I have replaced that already.

I will test the fuses in the morning and update you then.

Thank you.
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Sunday, November 8th, 2015 AT 11:42 PM
Tiny
ASEMASTER6371
  • EXPERT
Ok
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Monday, November 9th, 2015 AT 4:24 AM
Tiny
INDIANAWMN7798
  • MEMBER
So I checked the fuses that you recommended this morning and all tested good. I thought maybe it may have been the resistor, because when I tested the orange wire to the far left it tested good, so I decided to use the multimeter and tested both orange wires (they are next to each other) and they tested fine. The other wires I got no reading on. So I went and bought a brand new resistor and plugged that in. Blower is still not blowing on any speed. I had a gentleman in line suggest a toggle switch. Sounds like a bit more work than I know about but I'm not sure if that is a simple alternative than ripping the dash apart to replace the resistor wiring harness.

Any further suggestions or ideas are appreciated.
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Monday, November 9th, 2015 AT 9:34 AM
Tiny
ASEMASTER6371
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Who said anything about tearing the dash apart for wire harness?
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Monday, November 9th, 2015 AT 9:39 AM
Tiny
INDIANAWMN7798
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I was assuming that since it is behind the dash. If that's not the case then I am not sure as to what else I can replace. Sorry I am just not sure where to go from here.
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Monday, November 9th, 2015 AT 9:59 AM
Tiny
ASEMASTER6371
  • EXPERT
Ok, first, hook up the resistor and test for one leg at the blower motor to have 12 volts.

If it does, then good.

Next is to remove the connector and test for voltage from the other 4 wires. The feeds will come from the blower speed switch. Each wire will get a feed from each position of the blower speed switch
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Monday, November 9th, 2015 AT 10:03 AM
Tiny
INDIANAWMN7798
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Well at least some good news, one side of the blower motor like you said is getting the 12 volts. Tested all other wires for voltage without the connector and there is nothing.
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Monday, November 9th, 2015 AT 10:50 AM
Tiny
ASEMASTER6371
  • EXPERT
Can you post a picture of the control head?
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Monday, November 9th, 2015 AT 10:51 AM
Tiny
INDIANAWMN7798
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Here is the control head that I have.
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Monday, November 9th, 2015 AT 10:54 AM

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