Blower works on high only

Usmczo6 · Oct 12, 2020

Fellas I have a blower motor that is working on high only, I have not tried to diagnose anything thought I would ask on here first, I let it run for a while today after 5 minutes it started to make a squealing noise. I turned it off, turned it back on it went away, the heat is working the defrost is working, but the four position switch is only working on high, is this the blower motor or the switch?

Snoots · Oct 12, 2020

You are going to need a DMM or test light before we begin to diagnose it.
Have you looked up the schematic in the GMSB Tech Section?

animal · Oct 12, 2020

When I had that issue it was the resistor. I had one sitting here so it was easy as I just plugged in the new one and it worked.

Catbox · Oct 12, 2020

We are having the resistor issue now on our truck as well.
We just made a junkyard trip to find a couple of them as well as some other odds and ends.

Usmczo6 · Oct 12, 2020

Snoots said:
You are going to need a DMM or test light before we begin to diagnose it.
Have you looked up the schematic in the GMSB Tech Section?

I have the Chilton's manual,

bucket · Oct 12, 2020

Probably a resistor failure. You could diagnose it, or just put another one on it. In this case, I don't think anyone would judge you for just throwing parts at it, because it's cheap and usually the culprit.

A visual inspection is a must though. Check the blower fuse and look at the resistor connector for any melting or burning.

78C10BigTen · Oct 12, 2020

Id first say resistor, then the fuse holder over near the bulkhead (that was my problem) or the connector from the blower to the relay, they tend to melt.

Usmczo6 · Oct 12, 2020

Yeah I figure I'll throw a resistor in they can't be too much, I appreciate the quick responses. This is a different topic but you guys are pretty knowledgeable,I don't think my electric choke is working on my quadrajet with the 454,any ideas how to diagnose that I have a multimeter I have a test light, I'm pretty mechanical, but I have no idea how to test if the electric choke is working how long is it supposed to get power for etc, I basically have to pump the truck four or five times and 50° weather, and then hold it steady about 1500 RPMs with my foot, for a minute before it'll idle on its own, and it still takes 15 minutes to get up to about 200° operating temperature,which I'm not complaining about but I feel like in the winter time I'd like to have heat a little sooner than that

bucket · Oct 12, 2020

The choke coil should have a 12v supply whenever the engine is running.

HotRodPC · Oct 12, 2020

Resistor Failure. I had that problem on my 65 GMC. Turned out to be a broken spring. I put on rung into another and reconnected the spring. It changed the low setting speed a little but it fired it back up with Low and Medium again.

Usmczo6 · Oct 13, 2020

Looks like this thing is toast!

You must be registered for see images attach

Snoots · Oct 13, 2020

Only an Ohm-meter will tell you for sure.

Kane Bittner · Oct 19, 2020

Sounds like a bad blower motor resistor. Here’s a link to an example one.
The “squealing” is usually a dry bearing on the motor. Easiest fix is just replace the motor.
Good luck.

Kane Bittner · Oct 19, 2020

Sent it before I got the link pasted in. Sorry bout that.
https://www.classicindustries.com/product/g9825.html

Usmczo6 · Oct 19, 2020

Just a quick update, they finally got the correct blower motor resistor in at the local auto store, I put it in works 100%, the flange is a little smaller than the opening I'll just silicone around it, thanks for the help

Blower works on high only

Usmczo6

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