The Stovebolt Site Forums The Shop Area The Electrical Bay 1965 Chevrolet C10 - heater blower stopped working

1965 Chevrolet C10

Hi folks, so my 3 speed, control on the dash heater blower stopped working after work the other morning. As in, I turned it on, it went off... has not come back on.

When I got home I checked the fuse with a multimeter(ohms) and it tested good out of the fuse panel... checked the voltage across the fuse when I put it back in, still 12v.

Started looking for shorts or a pulled wire, nothing so far.

I guess the motor could have totally gone out at that moment or the switch on the dash which has been in there since I bought it 21 years ago.

Anyway, looking for other things to check, ways to troubleshoot.

Suggestions appreciated. Thanks.

I have the 1963 shop manual and the 1965 supplement as well so I can look stuff up in there too.

-Woogeroo

If you have 12V across the fuse, that means the fuse is bad. You should not have any voltage drop between the two sides of the fuse.

Can you get to the motor terminals? Once you get a good fuse in, I would check the voltage at the blower motor.

If you have power there, the issue is in the motor or its ground. If you don't, then move up to the switch amd check there.

Just keep moving up or down the circuit until you find where the power stops flowing.

Check the switch to see if you get any voltage thru it. I'd suspect it first, as it's a mechanical device and may have broken when you last turned it off. If you jumper across the switch, the motor should run at full speed if it's still good. If that happens and the switch doesn't make it run, then you've found the culprit.

thanks for the replies folks.

-Woogeroo

It was getting power to the switch heater motor switch and off the switch on the different settings, checked it behind the heater box, that plug down there, it was getting power there as well on different settings.

I have the blower motor out now, parts searching tomorrow.

Thanks for the replies.

-Woog

Well, the new blower motor did not come on at all all plugged in and mounted.

Bummer.

However, I tested it off the battery and the new blower motor works at least.

I have a blower motor resistor ordered as I am running out of ideas.

-Woog

p.s. for fun I tested the old motor, it still didn't run. I guess multiple things failed at once, maybe. It was only 12 years old.

That sounds like a bad connector/ground.

If you measure voltage at the plug, but the (tested good) motor doesn't spin, look for a corroded/damaged connector.

Voltage drop across resistance is a function of current flow. So if you have a high-resistance (corroded/damaged) connection, you will see full voltage with a multimeter because that only flows a milliamp or so. Then when you put the blower motor on and try to draw 10+ amps, the voltage drops to zero.

Hook a jumper wire to the motor and run it directly to the battery and see what happens.

Hook a jumper wire to the motor and run it directly to the battery and see what happens.


Yep. did that.



Waiting on a blower motor resistor... then I will check more wires/connectors.

I am wondering if it is just a short somewhere, if so I hope it is one I can find and fix.

Thanks for the replies folks.

-Woog

The wire off of the fuse panel that goes to the switch, when I wire it up to another 12v source, everything runs fine. Weird.

When I test the source on the fuse panel, the fuse is good, the source shows 12v on a multi-meter(on the fuse, outside the panel where the wire slides on, etc.)... and on the wire.

It is the original fuse panel, so could be some damage somewhere, but I am stumped.

*shrug*

Anyway, for now it is wired up to another power source(extra harness) with 12v and is working great.

Thanks for the replies folks.

-Woog

Check the back of the fuse box. I had other issues and found an issue on the back of the fuse box after I removed it from the firewall.