Resistor Defrost Control

[rocket88]

Hello,

My blower motors only works when i put the heater-control in the High position. In the Low position they don’t work.

I think that is a problem with a bad resistor ?
I have the upper dash off because of another problem and can see that the resistor is not lookin’ fine (see the picture).

A friend of mine told me that i could try to change the resistor for a new one.
Does anyone have experience with that ?
And which value of ohms should this resistor have ?

Kinds regards from the Netherlands,

Everhard

[Julien Abrahams]

I think it would help if everyone knew the model and production year. Is it a automatic climate control system? Or a pré 1964 car?

[rocket88]

How stupid !

It’s a 1956 Cadillac Sedan de Ville...

[J. Gomez]

Hello,

My blower motors only works when i put the heater-control in the High position. In the Low position they don’t work.

I think that is a problem with a bad resistor ?
I have the upper dash off because of another problem and can see that the resistor is not lookin’ fine (see the picture).

A friend of mine told me that i could try to change the resistor for a new one.
Does anyone have experience with that ?
And which value of ohms should this resistor have ?

Kinds regards from the Netherlands,

Everhard

Everhard,

Well that resistor has seen better day fro sure,  by the look it may be open.    Have you check it?

The resistance ohms value should be very low <1ohm, the main key is the resistance wire would need to handle high wattage to lower the motor speed.

You could check some of the newer blower resistor modules and use one of the resistors as a replacement. Just remember these resistors are made of nichrome wire and it can’t be solder it has to be spot welded or pressed in to the terminals.

I would also suggest since it is real close to the instrument cluster (ground) and to keep the heat from the area to cover the new one with gypsum plaster for protection as the original one has a ceramic coating.

Good luck..! 

[cadman56]

that is going to be tough fix.  I think the resistor is crimped/welded to the switch.  You may have to completely remove the switch assy. from the car to fix it.  See if you can determine if the resitor is open first, as suggested above.

[bcroe]

Fine if you can find an original replacement.  If not try and find out
the resistance.  Any resistance and wattage can be put together from
standard parts which I buy from industrial suppliers like Digikey or
Mouser.  These could be mounted in an appropriate place for the heat
they will generate, and wires run over to the original connections. 

Later cars mounted the resistors directly in the blower airstream. 
good luck, Bruce Roe

[cadman56]

I and many others on this forum should have replacements for this part.  It just requires the replacement of the whole switch assy from the dash.  It is a very laborious job.  I have  restored and repaired 4 56 dashes and it is not a fun job.