high speed fan

[ord27]

I can't find my original thread, but have not solved my issue

The max ac....highest fan speed doesn't work

What can be the culprit?

the part that attaches to the side of the unit?
the switch itself
the button control unit

am I missing a part on that list?

 

[69a100]

Your question is vague, are you saying that the blow doesn't work on hi, but other speeds are fine? If so, it's that coiled lookin piece pictured at the top that needs replacing. It's called a blower resister. Good Luck

 

[ord27]

yes, all speeds work except the highest. thanks for the post

 

[Tony Tee]

the high speed should get full 12 volts , bypassing the resistor. Correct? I would guess it's the switch??

 

[ord27]

I have an extra switch and control unit. Where can I find a new resistor?

 

[Tony Tee]

I have an extra switch and control unit. Where can I find a new resistor?

The resistor is for the slower speeds. I.would try using a jumper wire directly from the battery to the motor. And see if it blows better.

 

[69a100]

Where can I find a new resistor?

I don't know what year your workin on?

https://duckduckgo.com/?q=Mopar+blower+resistor&t=h_&ia=web
https://www.google.com/search?sourc...hUKEwirpt_dhO7rAhVNSK0KHQr2Af8Q4dUDCAk&uact=5

 

[ord27]

1970 Coronet

 

[Mick56]

When the resistor is bad, normally ONLY high speed works. As mentioned, run a hot wire directly to the fan and see if it's better.

 

[ord27]

I replaced both the switch and the button control unit (I had new spares for another build). Neither replacement fixed the issue. I ran a wire directly from the battery to the fan, and got the highest speed that I've been wanting.
On page 875 of the shop manual, it shows that the dark green wire runs from the high speed position of the switch, to the resistor and then to the blower motor off of the same tab on the resistor.
So
I'm guessing that the resistor is bad?
thoughts?

 

[69a100]

Your question is vague, are you saying that the blow doesn't work on hi, but other speeds are fine? If so, it's that coiled lookin piece pictured at the top that needs replacing. It's called a blower resister. Good Luck

So
I'm guessing that the resistor is bad?
thoughts?

That's what I told you 2 weeks ago back in post #2! Good Luck

 

[70chall440]

BTW Ford used the same part in mustangs, it has a slightly different design in that one corner of the outside block is cut at an angle but other than that I believe it is functionally the same and costs like $12.

https://www.summitracing.com/parts/...2SomIeT27SlWiXct69lcdjD3fNlpLwxcaAsasEALw_wcB

 

[ord27]

thanks.
69a100, I should have listened....

update. If I run direct from battery to blower motor, I get 12 volts and high speed. If I have all wires connect correctly, I measure 8.5-9 volts at motor with switch on high.
so, I disconnected the resistor (and broke the housing...ugh)(all coil wires look good and intact), and measure the dbl dark green wire, with fan on high....I get the same 8.5 -9 volts.

my thought, worse case scenario, was to just solder the dbl greens together and bypass the resistor on high (looks to be a pass through anyway).
But the low voltage has stumped me

seems to me that the problem must be upstream somewhere.

any comments will help

 

[69a100]

Dude, please! Spare yourself the frustration & hassle! Just get a a new one and stop making so much trouble, just do it! It's not that hard!!!!!!! Good Luck

 

[ord27]

thanks. I have the new part on order.
I was just curious about the voltage. I was thinking that it should be 12 volts all along the dark green wire

 

[ord27]

I see from other threads, that others are having similar issues.

I put a new, correct, resistor in yesterday.
I only have 2 speeds.
I measured the voltage at the fan, resistor, and switch. High speed measures 9.2 volts.

I have noticed that the fan speed increases as rpm's increase, but didn't measure voltage at higher than idle rpm's.

Once the Texas summer heat rolls around again, I might just run a switch direct from the battery and mount an on/off toggle under the dash.
May-September around here, the ac is either off or on high anyway