Having problems with your 1992 GMC Sierra ?

I am the original owner of a 1992 GMS Sierra Z71 pickup. It is just a full-size pickup, 5.7 liter motor with A/C and standard transmission. I currently have 2 problems. The 1st problem is the blower fan for the heat and a/c. It only has high speed now, no low or medium and was quite noisy. I replaced the blower fan motor with a new after markert blower fan thinking this would solve both problems. All it solved was the noise as I now have a quiet blower fan but still with only high speed. I

Posted / edited by AnonymousUser on : 11-12-2017

Answers :

Let us deal with the two very separate problems here.
\015\012The problem with the blower motor is that the blower motor speed control resistor is burned out, when this happens all you will have is high speed setting. The blower motor speed control resistor is located right next to the blower motor in the air ducting. It has an electrical connector going to it with 3 wires, the resistor is roughly oval shaped and would easily fit in the palm of your hand. It is held into the air duct work by two screws. See picture below.
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emissionwiz_150.jpg I will deal with the radio issue in a separate reply
Hi, the problem with the blower is probably the resistor. I think it's by the blower on your truck. You may have seen it there. The blower wires go to the resistor. There are additional wires in the resistor that go to the switch. The resistor is held into the heater box by a couple of screws. Take the connector off, remove the screws, and pull the resistor out. If it is bad, it will show heat damage. You can test it with an ohmeter for continuity. Sometimes the switch goes bad first and then causes the resistor to fail. After installing a new resistor, listen carefully as you change the blower speed to see if it has 2 distinct med and low speeds. If it doesn't hold a distinct speed when you giggle the switch, replace the switch or it will burn up your resistor again.
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\015\012For the radio, I have never heard of that behavior. Are there separate controls for the radio anywhere else in the truck? Like on the steering wheel or in the back seat? That is the only way I can imagine 2 radios would present the same issues. I will see if I can find a wiring diagram on that and get back to you.
Repair Help & Product Troubleshooting for 1992 GMC Sierra

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