Anyone ever try to fix a heat/AC swtich (in dash)

"DanKMTB" wrote: ( 98 Ranger )

The switch to control heat, defroster, and AC has been on the way out - the only setting that worked was high. Now it has died completely, even high does not work. Has anyone tried to fix one of these, or should I just bite the bullet and replace it. _____________________________________________

Switches are generally non-repairable. If your diagnosis of a bad switch is correct, your only option is to bite the bullet and replace the switch.

If you would describe the symptoms, someone may have a different diagnosis. For example, if the AC compressor works and the heater core gets warm, and the heater duct valves work, but the fan is intermittent, the most likely cause is a burned-out resistor module near the fan motor. Good luck.

Rodan.

It could be the fan itself that is worn out. I've had cars where the last speed to work was high and then nothing and it was the fan.

Thanks for the info. I had figured it was the switch only because I lost speeds 1-3 well before losing the high speed, but I guess it could still be attributed to the resistor pack. I'll have to see if I can find mine.

Symptoms are few: The lower 3 speeds stopped working all at once long ago, and now the high speed does not work either. Hard to tell for sure if the heater core and AC are working, since it's not blowing any air at all, but it seems they might be. Allowing the truck to run for an extended period of time does produce a small amount of heat in the cab. Can't really use the same test for the AC as it's ~20 degrees F here. I'm open to any ideas how to check these things.

Jeff's idea about the resistor seems it could be the ticket, based on some reading I've done since reading his post.

Thanks for the idea. I had figured that it wouldn't lose certain speeds one at a time if it were the motor - your experience seems to negate that theory. Something else worth checking for sure.

Confirm the blower motor is working. I think you should be able to hotwire it from the batttery, but there must be somebody here who knows. I've had the lower speeds go out on GM cars, and just replacing the blower motor got all right again. Sorry I don't know electrics enough to say more.

--Vic

Be wary of that, a worn fan will blow the lower speeds out of the resistor pack before blowing the top speed or failing.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:

Well, I located and removed the resistor pack. Right under the blower, passenger side, against the firewall. Based on the amount of corrosion and rust on that thing I think there is a really good chance we've got the culprit. Unfortunately, the monster plug that attaches to it is a real bear to get off. I located and removed the pack in 2 minutes, and spent 10 fighting with the plug with no success. I'm going to have to put it on hold for now until I have a second set of hands available to help me fight with it. I'm tempted to put a hair drier on it to loosen up the plastic, it's way cold here and I don't think that's helping. I'd hate to have to cut off the plug and replace it because I wasn't able to unplug the thing.

Anyway, thanks for the help so far. I'll keep updating to let you all know if this does in fact do it.

.

Thanks Jeff. Finding it was the easy part, it's unplugging it that threatens frostbite before success. The resistor pack was in horrible shape, as corroded as you could imagine - very easy to believe this is the culprit.

You did look that plug over to make sure that it didn't have a latch somewhere??

Tom J who had that happen once :-(

"DanKMTB" ( Re: Heater fan resistor pack. )

I located and removed the resistor pack. Unfortunately, the monster plug that attaches to it is very difficult to get off. I'd hate to have to cut off the plug and replace it. ___________________________________________________

The receptacle on a resistor pack usually has a little triangular plastic ear sticking out the side, to mate with a latchng finger on side of the mating cable plug. If your receptacle has that kind of latch, you can pry the latch finger outward with a knife or a screwdriver while you pull off the plug.

Good luck.

Rodan.

n resistor pack. )

It actually has 2 latches, one on each side. I did use a screwdriver to open the latches before trying to unplug it, with no luck. I also had a second set of hands help me, with me holding the latch open and the other party pulling on the unit while I held the plug. We were still unable to get it open. I've dealt with many plugs in my day, many of which were quite rusted and corroded (usually on salt water boats) and have never come across one this difficult to unplug. I'm at a loss on this one.

Just the fact that:

The plug is stuck, it sounds like the connectors melted together, to a certain degree.

This is common, and you can buy a replacement plug, as well as a resistor.

I recommend upon reassembly, you use a slight bit of: "Non Dielectric anti seize compound in the plug"

This will prevent future seizure of the plug, because the resistor generates a large amount of heat, as it reduces the voltage, and leads to higher current draw.

It actually has 2 latches, one on each side. I did use a screwdriver to open the latches before trying to unplug it, with no luck. I also had a second set of hands help me, with me holding the latch open and the other party pulling on the unit while I held the plug. We were still unable to get it open. I've dealt with many plugs in my day, many of which were quite rusted and corroded (usually on salt water boats) and have never come across one this difficult to unplug. I'm at a loss on this one.

Thanks. I was leaning toward having to replace the plug anyway, I had another go at it and simply can't get the thing apart. Argh. Oh well. Could it have melted just from the resistor pack going, or is this an indication of another problem I need to hunt down?

Thanks,

Dan

.

Thanks. I'll be sure to check the ground also.

Dan

Also, since you are not sure what the problem is,... if you will be fixing it by a form of trial and error (sometimes called throwing parts at it) you should start with the cheapest/easiest to get to parts first. If the fan motor is easy to get to and fairly cheap you might start with it since the worst that can happen is you have a new, but unneeded fan motor in it. If you start with the dash switch you could wind up with the whole dash apart getting to it and then finding out it's not the problem.

True. I'm going to start with the resistor anyway, it's inexpensive and in very poor condition. If that wasn't the problem, it would have been in time anyway. I'll put a fan motor next on the list.

I know what you mean about throwing parts at it, but considering how inexpensive the parts I'm looking at are vs. paying the dealership to fix it, even if I'm wrong I should still come out ahead. Plus, it allows me to get into the truck and learn things while replacing worn parts anyway.

I've had the dash apart in just about every vehicle I've ever owned for audio work, so I don't mind dropping the dash if need be. I'd rather do it in the summer, but that's what I get for not addressing this issue as soon as I lost the lower speeds. Oh well...