# Heater A/C blower speeds



## alanmay0 (Sep 3, 2015)

Hello, I have a 1967 GTO with factory A/C. The blower is a 4 speed blower. It only works on the 2nd and 4th speed. I have checked the resistor under the hood on top of the blower housing, I guess you could call it, and there is not burnt coil wires.

Wonder if it might be the blower motor switch that is on the dash?? Is there some way to check it before spending 80.00 for a new one??

Thanks in advance I have always gotten good information from this forum.

alan


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## Goat Roper (Oct 28, 2014)

Do you have a schematic and a DMM?
Not sure if this goes through the relay on the firewall but the only way to check the switch is to buzz it out with a DMM.
That control is hard to get to and you have to remove the A/C ducting to get to the 4 speed nuts that hold it to the dash panel so I would check all the connections and buzz the wires out before going that route.


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## alanmay0 (Sep 3, 2015)

Thanks for the information but I do not know what a DMM is or what buzzing means. Sorry not a electrical mechanic.


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## Goat Roper (Oct 28, 2014)

alanmay0 said:


> Thanks for the information but I do not know what a DMM is or what buzzing means. Sorry not a electrical mechanic.


A DMM is a Digital Multi Meter and you can get them at places like Rat Shack.
You can use the ohm meter part of it to check continuity a good one will have a buzzer and will buzz if the wire is good.
If the wire is hot you can check for voltage with the VOM part of it.
The schematics take a little getting used to, they will tell you which wire goes where off the switch and the colors.

There is also a relay on the firewall, not sure if that switch goes through it but that could also be bad or a bad connection to one of the tabs.
I bent one plugging in the connector and I couldn't get my fan to run.
I finally pulled it off the firewall, straightened the tab put the connector in while I could see the tabs and put it back on the wall and that fixed it.


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## BearGFR (Aug 25, 2008)

Not sure what you meant by "2nd and 4th" --- was that "medium-low" and "high", or "low-low" and "meduim-high"? If memory serves, only the first 3 speeds (low-low, medium-low, and medium-high) go through that resistor on the cowl. "High" is a separate direct circuit with its own inline fuse, that on my 69 connected directly to the alternator output.

Not sure if 67's used the same arrangement.

But --- regardless of the speeds you're actually missing, at least one of the ones that isn't working will be going through that resistor. If you're sure the resistor is good (check it with a meter to be sure, they can fail in ways that aren't visually apparent) then the problem almost has to be in either the switch itself or in the wiring between the switch and the resistor.

Bear


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## Goat Roper (Oct 28, 2014)

Hi Bear
The switch on the 67 with air has a 1 2 3 4 fan speed switch and the off position on the slider shuts off the fan.
There is also a separate harness that plugs into the main harness, different ones for A/C vs non A/C cars.
I rebuilt that control while I had the dash apart and someone had put a single port vac can on the engine side and I had to replace it with the proper 2 port.
The cable on the control was installed upside down and all the vac hoses were in the wrong places.
I also had to rebuild and reglass the plenum and used a vac pump on the bench along with the control to test it all before reinstalling.
The job was a bear (pun intended) someone had cut the heater core supports out to remove it from the inside and I had to source another whole unit to replace it.
Worst part of the restore was rebuilding and sealing the unit up and getting it all back together and installing it back in the car.
They don't make a repop for that plenum and they are all 50 years old and brittle so I had to use fiberglass cloth and resin to restore it.


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## BearGFR (Aug 25, 2008)

My 69 is the same --- 4 blower speeds all on the switch, off/on is controlled by the same slider that selects a/c, heat, or defrost.

I've been half-considering trying to revive my factory air system since I've got the motor out of the car anyway... my plenum is going to need some glass work too if I decide to do that.

Bear


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## Goat Roper (Oct 28, 2014)

On the '67 there is a dimple on the passenger side inner fenderwell and you have to drill a 1" hole to get to the nut.
I have a set of long handled magnetic nut drivers so I was able to get to it with the 7/16 driver.
I bought a 1" rubber plug for the hole.
The hack that replaced the heater core didn't know how to get the unit out so he just butchered the core support to remove it from the inside.
Of course the neck on the core broke and was leaking since it was just flopping around in there.
Nothing worked when he got done since he also screwed up the control and didn't have any of the vac hoses in the proper places.
I found the horseshoes for the leaf switches laying in the bottom of the dash panel and since I do pinball repair I had new contacts for the leafs and was able to repair the switch stacks.
The guy was a real hack and should have never touched the system and just bypassed the hose.
Probably didn't know how to do that either.
:/


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