Help A Rookie Diagnose Blower Motor Blowing Fuses

[YankeeFlyGuy]

The AC blower in my 81AC quit working so I started with replacing the fuse. I put a new fuse in, started the car and the blower worked fine. Then I sat down and accelerated away and as soon as the motor climbed in RPM's above idol it immediately quit working. I checked the fuse and it was blown again. I repeated a couple of times.

Just to be clear, center vent on the dash, second fuse from the back. What's my process for testing and chasing the issue?

Thanks y'all! I'll report back what I learn.

[Dpmulvan]

Your blower motor is on its way out. Unless you have a wiring issue short et but I would bet it’s the motor itself.

[X JBM X]

Following... I'm blowing AC fuses left and right also.

For mine, and not to thread hijack, I swapped my deck lid last year to tail-less, and this year swapped back, but also swapped the hinges from stock to the Rennline aluminum, adjustable... and wondering if perhaps I've got a bad ground...

[David Inc.]

Sorry OP your blower motor is probably dying. They all go eventually.

Originally Posted by X JBM X

Following... I'm blowing AC fuses left and right also.

For mine, and not to thread hijack, I swapped my deck lid last year to tail-less, and this year swapped back, but also swapped the hinges from stock to the Rennline aluminum, adjustable... and wondering if perhaps I've got a bad ground...

For me I started popping AC fuses when my switches were working on melting down. Mine's an '82 so not sure if it has your setup but there's a lot of current going through the fan switch.

[targa80]

There are two blower motors.
The first is the fresh air blower controlled by the three speed slider switch in the dash.
The second is the ac evaporator blower motor controlled by the three speed rotary switch in the center shifter console.

So to be clear which switch are you turning on and at what speed 1,2 or 3 does the fuse blow. Each blower motor is on a separate circuit from each other.

[EC900]

First attempt at operating the AC blower in this ?
I found my dealer installed AC (deleted) was setup to the wrong fuse, can’t recall which but it was tapped to the interior lights and clock or somewhere else, just too much load for 5 amps it think. Sometimes there’s a confusion to which position the fuse block runs. #2 or # 20 are “the second” fuse from the back…or is that the front! Here’s a fuse chart from my 77 owners manual if needed:

[wazzz]

If I read it correctly, the AC blower is the evap blower. It quits because the fuse blows when accelerating the engine. This may well be an alternator problem, or rather a voltage regulator problem. I would start by checking this.

[fintstone]

A fuse blowing means too much current across it. It can be almost any component in the subsystem (or a shorted wire/component). There is some pretty easy troubleshooting that you can do to narrow it down...that doesn't even require a meter or technical skills. Just isolate the problem by removing components downstream.

1. Fusebox/Fuse

A. Check to see if you have the right fuse...25A (blue)

B. Visually inspect the wires going to the fuse (#20) for chafing or other issue.

2. Fusebox/Relay

A. With a good fuse installed, swap the relay with another black one. Duplicate conditions (drive) with switch on and see if the problem goes away (fuse does not blow).

B. With a good fuse installed, remove your Air cond relay. Duplicate conditions (drive) with switch on and see if the problem goes away (fuse does not blow). The A/C fan will not work during this test.

3. Resistor Pack in return vent

Pull back your passenger side carpet and remove the floorboard. Take a look at the blower resisters and wiring. Check for chaffed wires and moisture (or any obvious signs of a problem).

4. Blower

With a good fuse installed, disconnect the two-wire blower connector in the smuggler's box. Duplicate conditions (drive) with switch on and see if the problem goes away (fuse does not blow). The A/C fan will not work during this test.

5. Line to clutch on compressor through Thermo switch for A/C (excess temp) and Temp switch.

Disconnect green/white wire from back of A/C switch or disconnect the connector at compressor. Ensure the contact/wire will not short out against another wire (wrap it with electrical tape or similar). Duplicate conditions (drive) with switch on and see if the problem goes away (fuse does not blow). The A/C fan should work during this test but the compressor will clutch will not engage (so the air will not get cold).