Noise not likely blower motor/wheel—what else?

[1980 Big Ten]

Loud, awful noise under passenger dash, even when the heating/cooling/fan settings are off. What other moving parts are under there? My guess is there’s a vacuum connection that’s loose. Letting off the gas pedal sometimes quiets the noise.

Grateful for any suggestions.

 

[PrairieDrifter]

Loud, awful noise under passenger dash, even when the heating/cooling/fan settings are off. What other moving parts are under there? My guess is there’s a vacuum connection that’s loose. Letting off the gas pedal sometimes quiets the noise.

Grateful for any suggestions.

I'm not sure if an 80 will shut the blower motor off completely, my 79 doesn't, as well as the early 70's trucks. I don't believe that changed until for sure 83-84 but probably 81-82. Unplug the single input wire on the blower motor then test again and report back.

 

[dvdswan]

If you have factory AC, then a vacuum noise of a hiss or possibly a squeal from a cracked line/connection.

As @PrairieDrifter said sounds about right. Early SB didn't have an off switch for the fan.

Disconnect the power to the fan from inside the engine compartment and see if noise goes away as @PrairieDrifter said.

 

[PrairieDrifter]

If you have factory AC, then a vacuum noise of a hiss or possibly a squeal from a cracked line/connection.

As @PrairieDrifter said sounds about right. Early SB didn't have an off switch for the fan.

Disconnect the power to the fan from inside the engine compartment and see if noise goes away as @PrairieDrifter said.

As well as the vent selector switch and connector, mine makes a little bit of noise sometimes while switching vents. Just sounds like a vacuum leak though.

 

[1980 Big Ten]

I'm not sure if an 80 will shut the blower motor off completely, my 79 doesn't, as well as the early 70's trucks. I don't believe that changed until for sure 83-84 but probably 81-82. Unplug the single input wire on the blower motor then test again and report back.

I stand corrected and, as always, so grateful for the members on this forum. I unplugged the wire and then the bad motor stopped. Looks like I’m in the market for a new motor. I like the way Rock Auto shows my options.

Thanks again!

 

[PrairieDrifter]

I stand corrected and, as always, so grateful for the members on this forum. I unplugged the wire and then the bad motor stopped. Looks like I’m in the market for a new motor. I like the way Rock Auto shows my options.

Thanks again!

Fantastic! The blower motor always on, on 70's trucks was part of some kind of "fresh air ventilation" so the blower motor always ran even if the selector was switched to off.

I and others opt to install a toggle switch inline, for the summer months. Some just unplug the blower motor. But that's a hassle unless you live in the desert. Most places it's hot in the day get pretty cool at night.

 

[1980 Big Ten]

I and others opt to install a toggle switch inline, for the summer months. Some just unplug the blower motor.

Huh. Good to know!

 

[brooksman9]

Pulled mine last week as it was making a lot of noise. Sprayed some PB Blaster in various placed and it quieted down considerably. Might be worth a try. At least until you get a new one.

 

[Turbo4whl]

If it is a buzzing noise, may just be some leaf trash that got in the housing.