Heater fan speed, should there be a high & low speed?

[slim811]

I was removing my heater box to replace the core, and removed the fan motor. I noticed it has only one speed high, on low the squirrel cage is not spinning. Is that how the 1971's are supposed to be? My friend showed me how to find the resistor and i removed it, it had only one coil. Is there something on the fan switch to allow for low speed. Thanks, Slim.

 

[dave67fd]

The heater control is a 3 position switch Off-HI-LO. In low, power is fed thru the resistor, in Hi mode it is bypassed. If it doesn't work in low mode you have a bad resistor, switch or the motor is just old and worn and needs the extra power to even spin it. Measure the resistor.. Not sure what the actual resitance is but it's low. Measure voltage after the resistor between hi and low. If you get voltage in both positions your switch is good.

Regardless, consider a motor upgrade.

 

[slim811]

Makes sense!

The heater control is a 3 position switch Off-HI-LO. In low, power is fed thru the resistor, in Hi mode it is bypassed. If it doesn't work in low mode you have a bad resistor, switch or the motor is just old and worn and needs the extra power to even spin it. Measure the resistor.. Not sure what the actual resitance is but it's low. Measure voltage after the resistor between hi and low. If you get voltage in both positions your switch is good.

Regardless, consider a motor upgrade.

Along with ordering a new core & seal kit will now order both the Heater/Blower and cage upgrade. I could ask my friend to test it, not good or certain I have the right tools or knowledge to test a resistor. Would be easy now to just replace resistor, then everything should be replaced. Will check with TBP about a resistor or local parts store. Won't make sense to borrow a used one off the other boxes I have laying around. Thanks you for responding. Since we are on the subject was having a discussion about the accordion style bellow seal. When I had my first Bronco 25 years ago, used to let this dangle in the winter to suck in already heated air from the cab. Also I would block the passenger side cold air duct. Thinking this was better to reheat the air already in the truck. My friend who is a mechanic for Ford over 30 years tells me the you want that air being blown in over the core. By the way is almost always right on the Bronco stuff. At any rate guess I will be adding a new stock thermostat and a gallon of antifreeze to my list. I think the PO might have a lower 170 thermostat because he keep top off and only drove in summer. Any thoughts? Thanks Again, Slim

 

[DirtDonk]

I could ask my friend to test it, not good or certain I have the right tools or knowledge to test a resistor. Would be easy now to just replace resistor, then everything should be replaced.
Will check with TBP about a resistor or local parts store.

If he doesn't have a chance to test it with an ohm-meter, you can simply hook it up to the new motor just the way it is right now, attach the power and ground wires to the battery and see if it starts up with 2 speeds.
If it does, you're good to go.

Not sure if they are even available new. Haven't seen them, but haven't looked much either. Maybe the Mustang crowd or the LMC type companies have them? They don't fail very often, but if they're available it might not hurt us to have some laying around anyway.

Won't make sense to borrow one off the other boxes I have laying around.

Actually, since they fail so seldom, it might not be such a bad thing after all. Chances are pretty good that most of the ones you find laying around will still work. Rust is likely the biggest issue, but easy to test.

When I had my first Bronco 25 years ago, used to let this dangle in the winter to suck in already heated air from the cab. Also I would block the passenger side cold air duct. Thinking this was better to reheat the air already in the truck. My friend who is a mechanic for Ford over 30 years tells me the you want that air being blown in over the core.

The way you did it, air was still being sucked over the core. It was just taking it from the inside rather than the outside.
The real downside to recirculated air is that it's not as efficient at defrosting the windshield. With an already sorry excuse for a defroster, that could make the difference in deciding whether to block off the fresh air intake or not.

At any rate guess I will be adding a new stock thermostat and a gallon of antifreeze to my list. I think the PO might have a lower 170 thermostat because he keep top off and only drove in summer. Any thoughts? Thanks Again, Slim

Yes, go with at least a 180° version. Some even bump it up to a 195°, but that's usually better with the EFI folks. While it can work with a carb, I think the 180 is a better choice. Double check of course, but that should have been the factory rating.

Good luck.

Paul

 

[slim811]

Thanks for posting Paul and Dave.

Yes I figured out how to use an ohm tester. Tested the resistor off the 2 boxes I had laying around. They both tested good in the 3 range. So I know when I pull my box I have a good resistor. Ordered the heavy duty blower motor and squirrel cage combination waiting for delivery. Looks like I have time to clean up one of the boxes, paint and get ready for the new heater core and seal kit. You were correct Paul, TBP does not sell a new resistor have to get a used one. Going to stay with my own Accordion style bellow, Looks OK small hole i can just tape, hoping the defroster hoses are still Ok. If not, Advance Auto sells them in different diameters. Can pick up a thermostat locally for less, could have also got a heater core for less also. But had to send away for the seal kit so I got the core listed. Ordered an extra seal kit if I ever need in future or when I get to my other 68 project. One of the old heater boxes the PO cut and modified the box to put in a larger core. It's inlet and outlet were a side by side versus the stock over & under style. Interesting may post a pix, wondered if he had any greater heat. Hoping this updated heater motor & high flow squirrel cage lives up to it's claim "You will be rolling the windows down because it's so warm." Paul jogging my memory I can recall wiping the front windshield with my sleeve In first bronco during the winter. So i may not be dropping and dangling the Accordion style air inlet this winter, allowing fresh air to enter

 

[DirtDonk]

Cool. Sounds like the list is being whittled away pretty good.

Not sure what you mean about the heater inlet/outlet being side-by-side though. Never seen an EB that didn't have them that way. So maybe it wasn't a PO mod after all?
Have you seen an over-under recently? With only those holes in the firewall?
Or could you be remembering a different type of vehicle perhaps?
Curious if there was ever a different version and I'd just never noticed.

Thanks

Paul

 

[slim811]

Definitely Modified from another vehicle. Wonder if it worked?

Cool. Sounds like the list is being whittled away pretty good.

Not sure what you mean about the heater inlet/outlet being side-by-side though. Never seen an EB that didn't have them that way. So maybe it wasn't a PO mod after all?
Have you seen an over-under recently? With only those holes in the firewall?
Or could you be remembering a different type of vehicle perhaps?
Curious if there was ever a different version and I'd just never noticed.

Thanks

Paul

Thought I would post some pixs of side by side comparison of the larger heater core + modification one PO made to a box, he had to cut firewall. Maybe you can see what I mean about the over & under in/outlets on the other larger heater core? Also decided to refurbish the box I plan to put in. Rust bullet & plastic refinish paint, do you think it will bring back that new car smell? lol

 

[slim811]

Pixs

Thought I would post some pixs of side by side comparison of the larger heater core + modification one PO made to a box, he had to cut firewall. Maybe you can see what I mean about the over & under in/outlets on the other larger heater core? Also decided to refurbish the box I plan to put in. Rust bullet & plastic refinish paint, do you think it will bring back that new car smell? lol

Ok hope this helps.

 

[DirtDonk]

Lookin' good there now. Yeah, looks like a PO attempt to get more heat into the cabin. Or at least to get away from the silly side-by-side arrangement that puts at least one hose square into the wheel well!
Substituted some core that they came across with ports where he wanted, but with larger, semi-compatible dimensions.
At least semi-compatible after some hackin'-and-hewin' to the housing!

Probably worked too.

Paul

 

[slim811]

Still waiting for replacement parts, gives me time to find my Dremel. I've been told heater box will need some modification to accommodate upgraded blower motor/squirrel cage.

 

[dave67fd]

I believe you have to cut the opening abit and/or drill a few new/more mounting holes.

 

[slim811]

Thanks Dave, getting pretty cold here at night lately. I would like to continue driving at least until the snow comes.