Blower motor issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rhamer88 · 10-22-2024, 11:11 PM

I’ve got a 1984 C10 and over the weekend my heater blower stopped working. I’ve been chasing wires a trying to see what happened and I discovered that the fuse for the blower is grounded. It didn’t pop or anything, but when I hook up my test light to it, as in the alligator clip side to a positive lead and the probe end on the fuse, it’s grounded. Is that correct? Doesn’t seem right.

If not, anyone have any idea why or how that happened and what I can do to fix it? Let me know if any further information is needed. Thanks in advance!

**HO455** · 10-23-2024, 11:59 AM

If you have the alligator clip hooked to a 12+ source and the probe end to the fuse and the heater switch is in the fan run position the test light should light as the probe is finding ground through the fan motor.

I'm not familiar with the early 80's C10 heater circuits but I am familiar with the late 80's and early 90's S10 circuits. I can't imagine they are very different.

I would start by disconnecting the blower and with the test lights alligator clip on the battery's negative post put the probe in the rubber connector that was connected to the blower. If things are working correctly you should be able to see differences in the test light as you cycle through the different settings on the blower control. If you get no light and your positive the fuse is good carefully inspect the connector as they can break inside the rubber boot.

If that appears to be good move the probe to the purple wire on the resistor mounted on the heater box and test again.

If still no light move the probe to the tan wire on the resistor. Here you should have the light on with the fan speed in low.

If still no light ad you know the fuse is good then you will need to pull the heater controls. My S10 knowledge probably won't help you as the switches are different switches.

Over the years that I've owned S10's I've had numerous blower switches fail, 2 of connectors at the blower motor fail and one resistor fail. If you inspect the blower control you should be able to visually see if it has overheated and failed.

I hope this helps.

Axle · Yesterday, 02:14 PM

1st place I would look is the blower resistor. Comes out with 2 screws. Normally you just lose a speed but it can fully open as well.
Also look inside the blower resistor connector for melting.

If an AC truck, theres a relay mounted to the evaporator box that feeds power to the blower resistor. But start with the resistor.

10-22-2024, 11:11 PM	#1
rhamer88 Registered User Join Date: Aug 2019 Location: San Diego, CA Posts: 17	Blower motor issue I’ve got a 1984 C10 and over the weekend my heater blower stopped working. I’ve been chasing wires a trying to see what happened and I discovered that the fuse for the blower is grounded. It didn’t pop or anything, but when I hook up my test light to it, as in the alligator clip side to a positive lead and the probe end on the fuse, it’s grounded. Is that correct? Doesn’t seem right. If not, anyone have any idea why or how that happened and what I can do to fix it? Let me know if any further information is needed. Thanks in advance! Last edited by rhamer88; 10-23-2024 at 12:03 AM.

10-23-2024, 11:59 AM	#2
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,266	Re: Blower motor issue If you have the alligator clip hooked to a 12+ source and the probe end to the fuse and the heater switch is in the fan run position the test light should light as the probe is finding ground through the fan motor. I'm not familiar with the early 80's C10 heater circuits but I am familiar with the late 80's and early 90's S10 circuits. I can't imagine they are very different. I would start by disconnecting the blower and with the test lights alligator clip on the battery's negative post put the probe in the rubber connector that was connected to the blower. If things are working correctly you should be able to see differences in the test light as you cycle through the different settings on the blower control. If you get no light and your positive the fuse is good carefully inspect the connector as they can break inside the rubber boot. If that appears to be good move the probe to the purple wire on the resistor mounted on the heater box and test again. If still no light move the probe to the tan wire on the resistor. Here you should have the light on with the fan speed in low. If still no light ad you know the fuse is good then you will need to pull the heater controls. My S10 knowledge probably won't help you as the switches are different switches. Over the years that I've owned S10's I've had numerous blower switches fail, 2 of connectors at the blower motor fail and one resistor fail. If you inspect the blower control you should be able to visually see if it has overheated and failed. I hope this helps. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

Yesterday, 02:14 PM	#3
Axle Registered User Join Date: Jul 2011 Location: SW Ontario Posts: 1,208	Re: Blower motor issue 1st place I would look is the blower resistor. Comes out with 2 screws. Normally you just lose a speed but it can fully open as well. Also look inside the blower resistor connector for melting. If an AC truck, theres a relay mounted to the evaporator box that feeds power to the blower resistor. But start with the resistor.



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