Blower Motor Resistor
June 23rd, 2009, 05:56 PM
#1
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Blower Motor Resistor
There is a blower motor resistor that is in the a/c 'box' on the firewall of my '71 442. My blower motor (new) will only work on the highest fan setting. I have a blower motor relay coming and will try that. If that doesn't work it likely is the blower motor resistor. My local O'Reilly and Advanced parts places don't show that part. Can any of you folks tell me where this resistor (held in by 2 screws) can be purchased. I don't see it in Fusick's. Thanks,
Mike
Mike
June 28th, 2009, 04:14 AM
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As a followup, I replaced the fan relay on this car. This was after looking at the blower motor resistor. You can evidently often times look at these and can see if one of the resistor wires is burned. There are two similar relays on the firewall of this car ('71 442). I replaced the one on the passenger side but the fan problem continued. We took the dash fan switch out and cleaned it. When put back in and switched from one speed to the other you could hear the relay 'clicking'. However, it was not the relay near the a/c box, it was the relay on the driver's side. So we put the new relay over on that side and the fan started working normally. I am not sure what the pass side relay does but it does not controll the blower motor (at least on this car.)
June 28th, 2009, 03:40 PM
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Mike,
I am having the same issues as you. I am not showing any power at all at the fan motor. Actaully I have had a dead draw on my battery which I was realting to this fan motor issue. I found that I had a bad cell ion a 1 year old battery from Murrays. Well the draw seems to be gone for the moment.
I am having the same issues as you. I am not showing any power at all at the fan motor. Actaully I have had a dead draw on my battery which I was realting to this fan motor issue. I found that I had a bad cell ion a 1 year old battery from Murrays. Well the draw seems to be gone for the moment.
June 28th, 2009, 10:18 PM
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High speed blower
The relay on the passenger side controls the highest speed of the blower, which is 12 volts direct to the motor separately fused (inline)...the other speeds are obtained by going through the resistors 
June 29th, 2009, 05:07 AM
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If you have factory defogger, then the lower pass side relay disables high blower speed when defogger is on to limit current draw. The 66A alt would not handle the load of both. Now WHY they put the high speed relay so far from the motor is beyond me... Longer wire runs for a high current device is not a good thing.
The defogger main relay is on the pass side also, but up higher. It will not engage unless the engine is running.
Last edited by Lady72nRob71; June 29th, 2009 at 05:09 AM.
July 28th, 2010, 03:43 PM
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OK here we go !
Just got a used AC blower motor and resistor in the mail.
My car has no AC box in the engine bay , just the 2 copper tubes from the heater core. So I just want the heater and defrost to work.
Interior heater box , wiring , ducts , switches are all there .
I have a aftermarket ac delete cover ready to go.
One problem is that I dont even know where the resistor goes or what plugs into the 4 prongs that are on it.
the blower motor has a single wire term on it that I do not know what is supposed to plug into it.
and a 1 " hole on the motor casing.(do I need to plug this ?
I can handle installing the blower motor but then what ?
Thanks Guys !
Just got a used AC blower motor and resistor in the mail.
My car has no AC box in the engine bay , just the 2 copper tubes from the heater core. So I just want the heater and defrost to work.
Interior heater box , wiring , ducts , switches are all there .
I have a aftermarket ac delete cover ready to go.
One problem is that I dont even know where the resistor goes or what plugs into the 4 prongs that are on it.
the blower motor has a single wire term on it that I do not know what is supposed to plug into it.
and a 1 " hole on the motor casing.(do I need to plug this ?
I can handle installing the blower motor but then what ?
Thanks Guys !
July 28th, 2010, 09:16 PM
#8
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the hole on the blower motor is for cooling the motor itself, it connects via a rubber pipe to a nipple on the heater box. plugging that hole could lead to very early failure of the blower motor due to overheating.
the blower motor resistor mounts into the heater box in the airstream from the blower motor discharge, it mounts there to cool the resistor elements which would burn out quickly due to overheating.
bill
the blower motor resistor mounts into the heater box in the airstream from the blower motor discharge, it mounts there to cool the resistor elements which would burn out quickly due to overheating.
bill
Last edited by BILL DEMMER; July 28th, 2010 at 09:24 PM.
September 6th, 2010, 07:06 PM
#10
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the hole on the blower motor is for cooling the motor itself, it connects via a rubber pipe to a nipple on the heater box. plugging that hole could lead to very early failure of the blower motor due to overheating.
the blower motor resistor mounts into the heater box in the airstream from the blower motor discharge, it mounts there to cool the resistor elements which would burn out quickly due to overheating.
bill
the blower motor resistor mounts into the heater box in the airstream from the blower motor discharge, it mounts there to cool the resistor elements which would burn out quickly due to overheating.
bill
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