1970 Blower Motor Resistor
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Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
1970 Blower Motor Resistor
I spent 3 hours searching for a replacement Blower Motor Resistor for my 70 454 WITH A/C and came up empty handed. Mine is a pile of rust & dust. The GM Parts Catalog (group 9.275) shows 3942651 for 69-71 and 6262652 for 72-82. Corvette Central lists their 453054 but they say it is the 6262652 replacement.... which is wrong for a 69-71. None of the "Supporting Vendors" list this part as far as I can tell. Anybody know what the issue is ? Discontinued ? No longer available ?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Whats the difference , I just looked at 69 , 70 and 74 diagrams and the connectors and wiring is the same in all 3 . Does it just mount different ? If so transfer the new resistors to your old mount.
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
The Ecklers and Corvette Central part are the 6262652 for 72-82. It looks very similar... but it must be different in some respect. Possibly the resistance of the coils. Too high a value, and the blower will run slow- too low a value, and the fan speed switch can burn out due to too much current flow. Maybe it's just the connector. I honestly do not know the difference. Most of the vendors list the 6262652 for 72-82 and clearly omit 69-71. I can surely order a 6262652 for 72-82 and see what the difference is.... maybe none. I was hoping someone else had gone through this little exercise already. Bummer.
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
1970 A/C #VAC6970
1971 A/C #VAC7100
1970 MAIN WITH A/C #VMA7000AC
1971 MAIN WITH A/C #VMA7100AC
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Update: I ordered the 1972-1982 A/C Blower Motor Resistor 6262652 and compared it to the original 1970 A/C resistor 3942651. The pin-to-pin ohms resistance of the 6262652 are exactly double the ohms resistance of the 3942651.
Here are pin use & values: (the pins are labeled on the resistor)
3942651 (white mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 1.1 ohms (.2 + .4 + .5 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.2 + .4 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.2)
6262652 (black mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 2.2 ohms (.4 + .8 + 1 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.4 + .8 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.4)
This implies that if you use the 6262652 to replace the 3942651 the fan motor will run approximately 1/2 half the correct speed in Low, Med1 and Med2. Hi fan operation is not affected because the fan switch bypasses the resistor and hits the high speed fan relay to drive the fan motor.
Mine is functional because I soldered wires to bypass the rotted spades. But it is butt ugly. Anybody know where the 3942651 can be found??
Note: Non-A/C cars used a different blower motor resistor altogether.
Here are pin use & values: (the pins are labeled on the resistor)
3942651 (white mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 1.1 ohms (.2 + .4 + .5 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.2 + .4 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.2)
6262652 (black mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 2.2 ohms (.4 + .8 + 1 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.4 + .8 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.4)
This implies that if you use the 6262652 to replace the 3942651 the fan motor will run approximately 1/2 half the correct speed in Low, Med1 and Med2. Hi fan operation is not affected because the fan switch bypasses the resistor and hits the high speed fan relay to drive the fan motor.
Mine is functional because I soldered wires to bypass the rotted spades. But it is butt ugly. Anybody know where the 3942651 can be found??
Note: Non-A/C cars used a different blower motor resistor altogether.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Update: I ordered the 1972-1982 A/C Blower Motor Resistor 6262652 and compared it to the original 1970 A/C resistor 3942651. The pin-to-pin ohms resistance of the 6262652 are exactly double the ohms resistance of the 3942651.
Here are pin use & values: (the pins are labeled on the resistor)
3942651 (white mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 1.1 ohms (.2 + .4 + .5 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.2 + .4 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.2)
6262652 (black mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 2.2 ohms (.4 + .8 + 1 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.4 + .8 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.4)
This implies that if you use the 6262652 to replace the 3942651 the fan motor will run approximately 1/2 half the correct speed in Low, Med1 and Med2. Hi fan operation is not affected because the fan switch bypasses the resistor and hits the high speed fan relay to drive the fan motor.
Mine is functional because I soldered wires to bypass the rotted spades. But it is butt ugly. Anybody know where the 3942651 can be found??
Note: Non-A/C cars used a different blower motor resistor altogether.
Here are pin use & values: (the pins are labeled on the resistor)
3942651 (white mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 1.1 ohms (.2 + .4 + .5 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.2 + .4 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.2)
6262652 (black mount)
Pin 1 goes to the fan motor +
Pin 4 to Pin 1 (Low Fan Speed) 2.2 ohms (.4 + .8 + 1 in series)
Pin 3 to Pin 1 (Med1 Fan Speed) .6 ohms (.4 + .8 in series)
Pin 2 to Pin 1 (Med2 Fan Speed) .2 ohms (.4)
This implies that if you use the 6262652 to replace the 3942651 the fan motor will run approximately 1/2 half the correct speed in Low, Med1 and Med2. Hi fan operation is not affected because the fan switch bypasses the resistor and hits the high speed fan relay to drive the fan motor.
Mine is functional because I soldered wires to bypass the rotted spades. But it is butt ugly. Anybody know where the 3942651 can be found??
Note: Non-A/C cars used a different blower motor resistor altogether.
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Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Update.... Dr Reb part is discontinued. Mine is good except for the corroded male connector tabs. I soldered one back on for a test but it broke off too easily. I'll have to braze new tabs on it.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
That's bad.. I looked at all the old boxes I have and only have the newer version. One is out of a 75 and appears to be original.
Couldn't you transfer the resistance coils from the original unit to the new one?
Food for thought.
Willcox
Couldn't you transfer the resistance coils from the original unit to the new one?
Food for thought.
Willcox
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
I had considered that... they are not welded or brazed... they are crimped. I figured the coils would be made out of stainless.. but they're not. It might be tungsten, nickel-chrome or some other rust resistant alloy. The brackets are made of regular steel... they will rust. I have brazed stainless to copper and other materials. I don't know what this stuff is. Apparently, it needs to be crimped unless that is just a cost saving measure. Anyhow... I could cut the coils off one but have no means of re-attaching them to the other legs.
