HVAC Blower Resistor Resisting

[ZEUS]

I scraped my windows of ice one morning while the VX was warming up and when I got back inside I got a whiff of an electrical-type burning smell. I switched off the HVAC, checked the fuse box in the dash, and during that time, the smell seemed to dissipate. All fuses there looked to be ok. But the blower never returned to life so I searched the forum and found out about the resistor behind the glove box. I pulled it out and sure enough the inner connections had come unsoldered. I fixed it in a jiffy and hooked it up again... but no workie! I took it out again to see if they instantly fried but they were just fine! I noticed a disclaimer on the housing that said, "DO NOT REPAIR" - does anyone know why that would be printed on the resistor? If the resistor "so commonly" roasts, does something else usually suffer because of it?

Any ideas on other things to check?

[mdwyer]

"DO NOT REPAIR" - does anyone know why that would be printed on the resistor? If the resistor "so commonly" roasts, does something else usually suffer because of it? Any ideas on other things to check?

ObWarning: I'm familiar with resistor blocks, but not necessarily the one as installed in the VX. Keep a grain of salt handy.

Resistors convert electricity to heat. If you don't get rid of the heat, the resistor will turn into what is jokingly called an LER - Light Emiting Resistor -- it will burn itself out.

To keep the heat down, they usually put the resistor block inside the air ducts so that they have plenty of air flowing over them. This is usually enough, and so they rarely overheat. However, sometimes you get a resistor that's just weak, I guess...

If you've got an inspection mirror and light, you might peek inside the hole for any airflow obstructions. When you removed the resistor pack, was it dusty? A buildup of dust could prevent adequate cooling.

The other thing to check is that the blower is spinning well. A sticky motor would draw more amps, which might cause more heat.

Those are really the only things I can think of that would make a resistor fail early. Otherwise, I think you've just lost a random roll of the dice. You're stuck with replacing the whole resistor block as a single unit, and hopefully you never see this problem again.

[etlsport]

do you have power to the hvac controls? i have had a bear of a time trying to figure out why i dont.. never considered the resistor

[ZEUS]

The compressor fires up like normal but the blower itself... oh, I have a '99, so I am not sure how much we differ in our HVAC controls behind the dash. Anyway, the controls do still have power based only on my observation of the compressor activating.

I was surprised how clean the resistor block was when I first pulled it; and looking thru the mounting hole everything seemed pretty clean but I guess there may be an obstruction somewhere. Next thing I plan to check will be the fuse block mentioned by carlymac and if that doesn't work I will try all the other things he mentioned...

Eric, how long has yours been on the fritz?

[tom4bren]

I've not seen our resistor but I'm guessing it's ceramic. If that's the case, soldering the leads may not have fixed it (the resistor element is down deep inside the ceramic). Since you know it fried (& yours is not the first) I'd replace that before doing anything else. Chances are pretty good that replacement of that part will get you another 100K miles.

[etlsport]

been acting up since middle of summer.. sounds like we have completely different issues though.. i dont get any power to my hvac controls on 2/3 of my startups.. used to be if i would remove the heater relay and replace it, problem solved for the trip and everything would run as normal.. eventually it started cutting out during driving too where id lose power to the controls (and the whole system would turn off).. i replaced the relay completely and that helped for like 2 weeks then back to how it was again.. right now i just have the relay removed completely and bypassed with a wire.. it works fine except the hvac system doesnt turn off with the car so i just have to make sure to switch it off manually

[deermagnet]

Back in the day, those resistors were burnin' up so fast, Tone was repairing and/or making his own. Check and see if he has any laying around.

I had the burning smell and the motor quit six years ago almost to the day. It was so long ago I was still under warranty. My dealer had the resistor and a motor shipped overnight via that Isuzu Parts Emergency Replacement Program or whatever it's called. With the weather around 0°, it was an emergency. It was no fun without the blower motor.

I actually don't know if the motor burned up also. I didn't need to know 'cuz I wasn't paying for it. It's been fine ever since. Just try a new resistor first, by whatever means ya can get one.

Mark

[tom4bren]

"Any ideas on other things to check?"

'lectric fan???? All that throttle response finally did you in.

[Triathlete]

I really wish we had an available smilie with the middle finger salute... just for you.

You could borrow one from Pirate 4x!

[tom4bren]

I try. Some things just never get old

[LittleBeast]

Occasionally I have to hit the glove box pretty hard with my hand to get the blower motor to start to work. Should I install a new motor or Resistor? On the '00-'01's our resistor is not cheap!

[yellowgizmo99]

sounds like motor, I did the same for a while and did the resistor and still had problem after a while, then replaced motor and put in old resistor and no problem since, do have an extra resistor incase that happens now though.

[MSHardeman]

LB, could it just be that something in the fan is stuck and when you hit the glove box it releases the fan so it can start spinning? I know I've heard some ticking once or twice out of my fan so something is in there hitting the fan blades.

[LittleBeast]

LB, could it just be that something in the fan is stuck and when you hit the glove box it releases the fan so it can start spinning? I know I've heard some ticking once or twice out of my fan so something is in there hitting the fan blades.

You know I thought the same thing. I guess I will take it apart and check it out tonight while I have the entire inside removed (long story). But I just thought if something was stuck in there I could hear it, but I found a blower motor on Amazon for $40 so I think I will try that after check for something stuck in there. Thanks everybody :-)