A question on resisters

48ford · December 28, 2006, 09:44:25 PM

Hi all,
I have a problem in the everyday beater,We have a 91 town car with automatic heat and cool.
But it started screwing up and I need a quick fix(cheap).
The blower only works on high but only on defrost,no blower on any other settings.
but I can put in a toggle switch and relay and get the blower to work on all the settings,but how big of a resister do I need so I can get the blower to slow down.
I can use a 3 position switch and two relays one for the full 12 volts the other going with a relay to lower the voltage to the motor.
The motor runs off a 30 amp fuse.
This thing is an electrical nightmare,all I want to do is run the fan slower.
and we are running out of nice weather quick.
Help if you can
Thanks russ

48ford · December 28, 2006, 09:47:05 PM

Quote from: "48ford"Hi all,
I have a problem in the everyday beater,We have a 91 town car with automatic heat and cool.
But it started screwing up and I need a quick fix(cheap).
The blower only works on high but only on defrost,no blower on any other settings.
but I can put in a toggle switch and relay and get the blower to work on all the settings,but how big of a resister do I need so I can get the blower to slow down.
I can use a 3 position switch and two relays one for the full 12 volts the other going with a relay to lower the voltage to the motor.
The motor runs off a 30 amp fuse.
This thing is an electrical nightmare,all I want to do is run the fan slower.
and we are running out of nice weather quick.
Help if you can
Thanks russ

Do you think a balist resister would hold up?

enjenjo · December 28, 2006, 09:51:41 PM

You can get the correct resistor for about $25, and they are fairly easy to change.

I have seen cars burnt up by using the wrong resistor on the heater motor, they get hot!!!

Dave · December 29, 2006, 05:47:15 PM

Quote from: "enjenjo"You can get the correct resistor for about $25, and they are fairly easy to change.

I have seen cars burnt up by using the wrong resistor on the heater motor, they get hot!!!

and why do they get hot? its because they have to. the restance is what gets rid of voltage and when you do that it makes heat. So if you were gonna use a resistor or a few resistors from say radio crapp the only real stipulation is you get the proper wattage. Thats where fires start. If you get a resistor the same ohms as the one being replaced and lower wattage it will burn up (get it burn).. The manufactures have worked this stuff out and know what works and made switches that work so if it was me thats the way id go.. The only time you want a lot of heat out of a resistor is when you actually use it for heat (IE: silicon carbide glow bars)
We use em in a brazing oven. Its a big silicon carbide resistor. Add big time voltage get heat

Dave

58 Yeoman · December 29, 2006, 06:44:12 PM

The resistor in my GF's Chrysler burned out a couple years ago. We replaced it again around Thanksgiving this year. Now, it's out again. The part is warranted by Chrysler, but I wonder why it went out again so soon? Could the motor be getting bad and drawing more power?

enjenjo · December 29, 2006, 07:26:23 PM

Quote from: "58 Yeoman"The resistor in my GF's Chrysler burned out a couple years ago. We replaced it again around Thanksgiving this year. Now, it's out again. The part is warranted by Chrysler, but I wonder why it went out again so soon? Could the motor be getting bad and drawing more power?

Most likely, the current draw from the bad resistor has burnt the contacts on the switch, creating more heat.