Blower fan for defrost won't turn in 1976 corvette

[Dave91266]

Hello, I have a 1976 Corvette Stingray, and the problem I am having is the blower motor for the defrost at the dash will not turn on. I move the fan switch from low to high and get nothing, and have moved the thumb rollers to the heat and defrost position, and still nothing, not even a sound. I checked the fuses at the fuse block under the driver side dash, and all the fuses are good. Any help or advice would be greatly appreciated! Thank you, Dave in Northern Ohio

 

[LLC5]

Hello, I have a 1976 Corvette Stingray, and the problem I am having is the blower motor for the defrost at the dash will not turn on. I move the fan switch from low to high and get nothing, and have moved the thumb rollers to the heat and defrost position, and still nothing, not even a sound. I checked the fuses at the fuse block under the driver side dash, and all the fuses are good. Any help or advice would be greatly appreciated! Thank you, Dave in Northern Ohio

The first thing to check would be power (12V battery +) to the flat insulated connector with key on and high speed selected, and ground (battery -) to the blower motor mounting screws itself, this can be done with a test light or voltmeter. If both are good, try tapping the motor lightly with something solid and the key on and fan switch on high speed, if it starts working you may get a few more miles out of it but it will need to be replaced. Good luck with it.

 

[Dave91266]

The first thing to check would be power (12V battery +) to the flat insulated connector with key on and high speed selected, and ground (battery -) to the blower motor mounting screws itself, this can be done with a test light or voltmeter. If both are good, try tapping the motor lightly with something solid and the key on and fan switch on high speed, if it starts working you may get a few more miles out of it but it will need to be replaced. Good luck with it.

I jiggled the wires going into and from the blower motor and only worked on low speed setting, but not on the high speed setting. I started the car, and worked again on low, when I shut the engine off, with the ignition on, the low speed setting on the control panel goes dead. With the car running, or not running, I now get nothing from the blower motor, funny thing is, it worked just fine a few days ago! I'll re-check the fuse again.

 

[LLC5]

I jiggled the wires going into and from the blower motor and only worked on low speed setting, but not on the high speed setting. I started the car, and worked again on low, when I shut the engine off, with the ignition on, the low speed setting on the control panel goes dead. With the car running, or not running, I now get nothing from the blower motor, funny thing is, it worked just fine a few days ago! I'll re-check the fuse again.

Try LIGHTLY tapping the blower motor with a solid object (small hammer, end of a ratchet, etc) with the engine running and switch on fast speed and see what happens.

 

[Dave91266]

Try LIGHTLY tapping the blower motor with a solid object (small hammer, end of a ratchet, etc) with the engine running and switch on fast speed and see what happens.

I tried just about every method in the book, and still no power to the blower motor, or fan speed switch. The wiring that goes to AC/heater panel in front of the shifter is all connected, no loose wires, and the thumb rollers move as intended. Isn't there a in-line fuse under the hood near the blower motor between the firewall and passenger side fender? Could this have anything to do with the blower not working? Thanks again.

 

[Dave91266]

I tried just about every method in the book, and still no power to the blower motor, or fan speed switch. The wiring that goes to AC/heater panel in front of the shifter is all connected, no loose wires, and the thumb rollers move as intended. Isn't there a in-line fuse under the hood near the blower motor between the firewall and passenger side fender? Could this have anything to do with the blower not working? Thanks again.

Does anyone know exactly where the inline fuse for the blower motor is located? On 1976 Corvettes, which is what I have, I heard it is located just under the driver side front fender, just forward of the master cylinder. What does it look like? Lastly, where is the high speed relay for the blower motor located? Might have to replace that as well. Just trying to do some troubleshooting, so I won't have to spend a great deal of $$ in the long run. Any help is greatly appreciated. Thank you

 

[bill81vette]

Try changing the fuse itself.I had one go bad once with the same problem... it was corroded but you really couldn't tell.

Sent from my DROID RAZR using Tapatalk

 

[Dave91266]

Can't locate inline 30A fuse for blower motor-1976 Corvette

Try changing the fuse itself.I had one go bad once with the same problem... it was corroded but you really couldn't tell.

Sent from my DROID RAZR using Tapatalk

I searched and searched for the inline fuse in reference to the blower motor at the passenger side firewall and found nothing. I heard the inline fuse for the blower motor is on the driver side under or near the master cylinder for 1976 Corvettes, which is what I have. I searched for a orange wire that leads to the inline fuse, and found no such wire. SO, I still have the problem with no power to the control panel on the center console, and no power from the blower motor. I checked fuse at the fuse box and believe the fuse for the heater is blown......again, as I changed the fuse with a new one the other day. If I can locate the inline 30A fuse for the blower motor, I am almost certain that is the problem, I just can't locate it anywhere. My Vette has the L48 350, automatic, AC with 58K original miles. Hope this would help. Any help or knowledge with this type problem, I would appreciate it very much. Thank you

 

[Dave91266]

I searched and searched for the inline fuse in reference to the blower motor at the passenger side firewall and found nothing. I heard the inline fuse for the blower motor is on the driver side under or near the master cylinder for 1976 Corvettes, which is what I have. I searched for a orange wire that leads to the inline fuse, and found no such wire. SO, I still have the problem with no power to the control panel on the center console, and no power from the blower motor. I checked fuse at the fuse box and believe the fuse for the heater is blown......again, as I changed the fuse with a new one the other day. If I can locate the inline 30A fuse for the blower motor, I am almost certain that is the problem, I just can't locate it anywhere. My Vette has the L48 350, automatic, AC with 58K original miles. Hope this would help. Any help or knowledge with this type problem, I would appreciate it very much. Thank you

In my 1976 Vette, I have a small block with the casting number 3951511 on the rear driver side of the block. That tells me this is a 400 small block. The suffix code on the right front engine pads is CPK, which comes back to a 1972 400 small black 4-bolt main. I bought this Vette a couple months ago as a driving project, and was told it was a numbers matching engine. The L48 350 I assume was pulled, and this 400 engine was installed at some point. This is the way the car was when I bought it. Apparently, the guy I bought this from did not have any knowledge of the engine, or simply assumed it was stock. The 400 small block in my car has a harmonic balancer that appears to be a 350 harmonic balancer, as 400s came with a external balanced harmonic balancer. Again, I have a 400 with the casting number 3951511 with a 350 dampner. Could this engine be a destroked 377 small block? Has a very mild cam, like a RV cam, heads look stock, cast iron 4 barrel intake qaudrajet carb. Any thoughts? Just trying to see what type of engine I have.Thanks

 

[LLC5]

In my 1976 Vette, I have a small block with the casting number 3951511 on the rear driver side of the block. That tells me this is a 400 small block. The suffix code on the right front engine pads is CPK, which comes back to a 1972 400 small black 4-bolt main. I bought this Vette a couple months ago as a driving project, and was told it was a numbers matching engine. The L48 350 I assume was pulled, and this 400 engine was installed at some point. This is the way the car was when I bought it. Apparently, the guy I bought this from did not have any knowledge of the engine, or simply assumed it was stock. The 400 small block in my car has a harmonic balancer that appears to be a 350 harmonic balancer, as 400s came with a external balanced harmonic balancer. Again, I have a 400 with the casting number 3951511 with a 350 dampner. Could this engine be a destroked 377 small block? Has a very mild cam, like a RV cam, heads look stock, cast iron 4 barrel intake qaudrajet carb. Any thoughts? Just trying to see what type of engine I have.Thanks

Are you saying that the ground source to the blower motor is good, and that the blower motor is only missing the battery positive source to operate?

 

[Dave91266]

Are you saying that the ground source to the blower motor is good, and that the blower motor is only missing the battery positive source to operate?

I assume the ground source to the blower motor is good since it was working fine a couple days ago. I don't have a volt meter to check it, but something is wrong as I tried other methods to pinpoint problem, and came up on the short end. A bad relay or resistor maybe? I can't locate the 30A inline fuse for the blower motor in the engine compartment. That may be the problem, but I cannot locate it.

 

[LLC5]

I assume the ground source to the blower motor is good since it was working fine a couple days ago. I don't have a volt meter to check it, but something is wrong as I tried other methods to pinpoint problem, and came up on the short end. A bad relay or resistor maybe? I can't locate the 30A inline fuse for the blower motor in the engine compartment. That may be the problem, but I cannot locate it.

If memory serves me correctly, the 30A inline fuse that you are looking for is usually near the firewall somewhere, but it is only for high speed. If that fuse is the only problem in the system then all the other fan speeds should work fine, do they?

 

[Dave91266]

If memory serves me correctly, the 30A inline fuse that you are looking for is usually near the firewall somewhere, but it is only for high speed. If that fuse is the only problem in the system then all the other fan speeds should work fine, do they?

All the fan speeds do not work at all. No power to the control panel, or the blower motor. I'm thinking the relay or resistor may be bad. I did find a in-line fuse, 30A I believe located in the battery compartment behind the drivers seat. But I doubt that would have anything to do with the blower not working.

 

[bill81vette]

My fuse is located under the dash mounted on the firewall
where you left foot would be when sitting in the vette.
it had tested good but wasn't letting the power go to the switch...
if the resistor was bad the only speed you would have is the high speed.

 

[Antz81]

All the fan speeds do not work at all. No power to the control panel, or the blower motor. I'm thinking the relay or resistor may be bad. I did find a in-line fuse, 30A I believe located in the battery compartment behind the drivers seat. But I doubt that would have anything to do with the blower not working.

The 30A inline fuse you are looking for would only stop the blower from running at high speed. All other speeds would still be fine. You say the ground is okay because it was running a few days ago; but have you checked it?
Causes for the blower to not run at any speed would be
1. 25A fuse in fuse panel gone.
2. Bad ground.
3. Bad switch.
4. Fault in wiring loom.
5. Faulty blower motor
You say you have checked to fuse panel and they are all ok. I would check the ground next. Then the switches.
This would all be easier with a voltmeter.

 

[Dave91266]

The 30A inline fuse you are looking for would only stop the blower from running at high speed. All other speeds would still be fine. You say the ground is okay because it was running a few days ago; but have you checked it?
Causes for the blower to not run at any speed would be
1. 25A fuse in fuse panel gone.
2. Bad ground.
3. Bad switch.
4. Fault in wiring loom.
5. Faulty blower motor
You say you have checked to fuse panel and they are all ok. I would check the ground next. Then the switches.
This would all be easier with a voltmeter.

I found a black wire with a plug at the end, and it plugs into just under the blower motor (passenger side firewall). Is this the ground wire for the blower motor? It goes right through the firewall and under the dash. I know where the blower motor resistor is, but not the relay. Any advice? I just installed a new GM OEM switch to control the fan speeds, but learned the switch is not the problem.

 

[Antz81]

I found a black wire with a plug at the end, and it plugs into just under the blower motor (passenger side firewall). Is this the ground wire for the blower motor? It goes right through the firewall and under the dash. I know where the blower motor resistor is, but not the relay. Any advice? I just installed a new GM OEM switch to control the fan speeds, but learned the switch is not the problem.

The ground wire is black, but not sure if it should be going through the firewall. If there is no other black wires connected to your blower then this is probably the ground.
The relay is mounted on the evaporator core housing. This wouldn't cause the loss of all speeds though. But could be useful for some tests.

 

[Dave91266]

The ground wire is black, but not sure if it should be going through the firewall. If there is no other black wires connected to your blower then this is probably the ground.
The relay is mounted on the evaporator core housing. This wouldn't cause the loss of all speeds though. But could be useful for some tests.

The ground wire is grounded as it should be. I checked again to see if the 25A fuse at the fuse box was still good, and it is. I installed a brand new switch at the panel, in front of the automatic shifter, I lightly tapped the blower motor with the fan switch set on high (with the car running and not running), and I still have no power to the blower motor. Possible causes I can only think of at this point: No power to the blower motor, bad blower motor.......period. Resistor, relay, I just can't seem to pinpoint the problem. It worked just fine a little over a week ago. Blower motor came on, had heat coming through the ducts, all speeds worked except high, now absolutely nothing.

 

[Antz81]

The ground wire is grounded as it should be. I checked again to see if the 25A fuse at the fuse box was still good, and it is. I installed a brand new switch at the panel, in front of the automatic shifter, I lightly tapped the blower motor with the fan switch set on high (with the car running and not running), and I still have no power to the blower motor. Possible causes I can only think of at this point: No power to the blower motor, bad blower motor.......period. Resistor, relay, I just can't seem to pinpoint the problem. It worked just fine a little over a week ago. Blower motor came on, had heat coming through the ducts, all speeds worked except high, now absolutely nothing.

Do you have a volt meter (or anything to test for voltage)? Check across the blower motor (on high and another speed) This will tell you if you are getting power to it.
It was just the speed switch you replaced? not the master switch also?

 

[Dave91266]

Do you have a volt meter (or anything to test for voltage)? Check across the blower motor (on high and another speed) This will tell you if you are getting power to it.
It was just the speed switch you replaced? not the master switch also?

I didn't replace the master switch, just the speed switch. These parts are priced fairly cheap, but I just want to make sure just what parts I need to get the blower motor working again at the switches. I wouldn't doubt it is a bad blower motor, since it looks original and being 38 years old. I don't have a volt meter, but it would be wise to pick one up! Since I don't have a volt meter, are there any other ways of troubleshooting to help pinpoint the problem.