heater resistor

[bigmac73]

what are the signs of the heater resistor going bad? this morning my defrost was blowing hard and I could here it then it got quiet but still blowing not so hard but okay I guess, the I cycled the lever and it started blowing hard again sometime I can hear it go up and down as far as the air being blown

[davepl]

Search first please.

Resistor wouldn't change, it'd work or not I imagine. There are no levers involved, only a switch.

I think you need to post a more detailed and easy to read description of what you've tried and what the results are. What happens in each of the switch positions? What happens in the lever positions as far as where the air comes out? What do you think should be happening instead? Etc.

[bigmac73]

Originally Posted by davepl

Search first please.

Resistor wouldn't change, it'd work or not I imagine. There are no levers involved, only a switch.

I think you need to post a more detailed and easy to read description of what you've tried and what the results are. What happens in each of the switch positions? What happens in the lever positions as far as where the air comes out? What do you think should be happening instead? Etc.

I think you are over thinking it a little, there is a lever since I do not have AC , and yes the resistor would since it controls the fan speed, depending on the position of the fan speed lever,

[davepl]

Originally Posted by bigmac73

I think you are over thinking it a little, there is a lever since I do not have AC , and yes the resistor would since it controls the fan speed, depending on the position of the fan speed lever,

Well, if you want to split hairs, we're both wrong, as they both have levers. The lever on the AC switch is just a lot shorter than the lever on a non-AC truck. Right?

Anyhow, can't help without data. At a very minimum tell us crisply what happens in each of the fan speed settings.

Because poverty trucks don't have the relay, it's much more straightforward. If a resistor is shorted typically multiple settings act as HIGH. If a resistor is broken, it might not work at all -unless- it's set to HIGH. There are two resistors on the little board. It's inside the heater air path so it doesn't heat up too much and to isolate it from touching anything while hot.

I'd be more helpful with a schematic, but it's your truck, and I'd still like to hear all the answers to the diagnostic questions before I do too much legwork on this.

[chevytruckluver]

Fan speeds are controlled through a 3 step resister coil. When the fan is running in high speed it bypasses this resister and the fan gets a full 12 volts to the fan motor. If the fan has stopped in high speed only, check the fan relay. If its starting and stopping I would look at the speed switch. good luck

[hamjet]

On mine, the lever cable was just on the verge of being on high position before it hit the right side of the control bezel. If I moved it to the left and moved it quickly to the far right it would be just enough to get it on high speed. (sloppy cable after 43 years, maybe an adjustment to the cable?) Reach underneath the next time and see if you can move the lever over more on the heaterbox..