Blower Motor Resistor

redvettemike · June 23rd, 2009, 06:56 PM

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

redvettemike · June 28th, 2009, 05:14 AM

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.)

tim72 · June 28th, 2009, 04:40 PM

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.

Yellowstatue · June 28th, 2009, 11:18 PM

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

Lady72nRob71 · June 29th, 2009, 06:07 AM

Quote:

Originally Posted by redvettemike

I am not sure what the pass side relay does but it does not controll the blower motor (at least on this car.)

Did this car have rear defogger? It almost sounds like it...
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.

redvettemike · June 29th, 2009, 03:14 PM

Rob: You are correct. The car does have a rear defogger.
Thanks,
Mike

June 23rd, 2009, 06:56 PM	#1 (permalink)
redvettemike Registered User Join Date: May 2009 Posts: 71	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

June 28th, 2009, 11:18 PM	#4 (permalink)
Yellowstatue Certified Fanatic Join Date: Jan 2009 Location: Too close to Toronto!! Posts: 567	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 __________________ '57 S88 HC et al; '68 442 M20; '68 442 M21; '68 W30; '68 Vista et al; '80 -'84 Regency et al; '96,'98.'99 Aurora..Ignition ON

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June 28th, 2009, 05:14 AM	#2 (permalink)
redvettemike Registered User Join Date: May 2009 Posts: 71	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, 04:40 PM	#3 (permalink)
tim72 Registered User Join Date: Feb 2009 Posts: 119	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.

June 29th, 2009, 03:14 PM	#6 (permalink)
redvettemike Registered User Join Date: May 2009 Posts: 71	Rob: You are correct. The car does have a rear defogger. Thanks, Mike