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Discussion Starter · #1 ·
It's the middle December in Ohio, and of course my heater fan/blower stops working. Here are some things I've tried. I am guessing it could be the heater control switch unit itself, but I wanted to see if anyone else had another theory or another possible test. Here's what happened:

I plugged a new resistor module in. No dice. I plugged a new fan in. No dice. So it's not the resistor, and it's not the fan. (Both have been replaced already anyhow a couple years back)

Then, I ran a multimeter on the blower plug itself (purple wire going into the fan), and the main red hot wire ("C" in the connector) going into the resister/blower harness. Very weak voltage.

I checked the relay fuse under the dash. It's fine. I jiggled the connector to the resistor, oddly enough, shorthly thereafter, I suddenly I'm see 12 volts in the hot wire ("C" on the harness). It could have been a coincidence, but at that point I suspected it was the connector hardness/pigtail going into the resister/blower. I got a new resistor connector (5 terminal plug, not 7 terminal most parts stores only have the 7 terminal, I had to go to the dealer for the 5 terminal).

I spliced in a new connector. Still no blower.

I ran the multimeter on the "C" hot wire again. Weak voltage (.04 on the multimeter). I yanked the dashboard plastic. I unscrewed/unplugged/plugged the heater control / climate control knob assembly. It's working again. Do you guys think it could be the knob/heater/climate control module? The temp setting lights burned out in mine recently, so I'm wondering if it's having a meltdown inside. I opened it up and it looked like a bunch of circuit boards, so I didn't mess with it. Hopefully, this is the problem, but again, just seeing what you guys think. Going nuts here, and I'm not sure what else it could be. Thanks!
 

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I would check power there, and at the resistor as well. Find where the power drops, and you find the problem. Blower control switches can fail, nothing lasts forever.
 

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Discussion Starter · #3 ·
Cool, thanks...so at least I'm not crazy for thinking it *could* be that, lol. I'm going to swap out the heater control switch module with a wrecker unit to see if it still acts up. At this point, I've swapped out all major components past the switch - resistor, fan, etc, no dice, so hopefully that's what it is. It sucks because I don't lose power all the time, and when it does stop running, the voltage is just weak, not 0, so at this point I'm wondering if one of the wires inside the module itself is breaking down from the heat - the bulbs inside of it burned out on me a while ago, so maybe something is melting down in there. Based on the multimeter checks I've done, I am suspecting the power is failing before the resistor, which then leads me to believe that the only logical reason, aside from a possible bad ground somewhere, is an issue integrated either with the switch itself, or something else going haywire inside the dash wiring harness. The wrecker unit is coming this week, hopefully the one in there now doesn't quit on me again before then.
 

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Discussion Starter · #4 ·
Threw in a new fan/temp/vent control switch unit in, and the problem didn't go away. While I had the new one plugged in and dismounted, I reached behind where the unit screws in, and I jiggled the wiring harness connection - magically, the heater fan turned on. So, I'm going to guess that the problem is somewhere around that harness. I squeezed the connection as tightly as I could, I guess I'll run it for a while and see if it keeps working. I tried to see how I could possibly get to it - it's buried inside the dashboard, and there doesn't seem to be an easy way to get to it.
 

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Guess you found the problem at least.
 

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Discussion Starter · #6 ·
Yea, hopefully. I'm having a hard time finding part numbers/locations/specs on the different harnesses and the connectors inside the dash. Do you guys know of any sites or anything I can check to see which harnesses route to/from the HVAC control unit? Would it be best to go in there from underneath or above?
 

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Discussion Starter · #8 ·
No developments yet, unfortunately - I have two possibilities right now - either the ignition switch, or adding a capacitor. I'm waiting on both to arrive FedEx - it's been working here and there, and I have a cig plug bypass to get me by until I can chase the gremlin down. Most of the research I've done points to the blower control module, the blower control harness at the module, or the blower itself. In my case, it's none of them, so I'm in a position where I'm chasing a ghost at this point. My plan is to try the ignition switch first, since the capacitor fix from what I have seen did not solve the problem for some of the Pontiac folks.
 

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I just bought a 2001 Impala last week and was having the same problem with the blower. I noticed the blower would cut on and off when i wiggled the key in the ignition switch or turned the key past start when it was running. I figured it had to be the ignition switch from my research.

I bought a switch from Autozone today for $87 plus tax and installed it in about an hour using the instructions from a sticky posted in the DIY section. It was easy to do and solved my problem. The dealer quoted me $373 to replace the switch.
 

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Discussion Starter · #10 ·
Cool! Yea, a new ignition switch didn't do it for me, I threw one in on Sunday, and I'm still having a problem (King's sticky was spot on) - - Maybe the key-wiggle you did is a good troubleshooting tip for the switch, for me, I tried that before replacing the switch and it didn't seem to make a difference - I tried it anyways since I'm kind of running out of ideas. Good thing you did it yourself, sounds like you saved a bunch of $$ - I have one more thing I'm going to try (wire in capacitor 25073556 to hot/ground in the blower control module harness) - GM has the capacitor fix listed for 2004-2005 model years only, not sure why, but hopefully that does it since I'm running out of ideas.
 

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Discussion Starter · #11 ·
TSB #05-01-39-001A, wiring in capacitor ACDelco #25073556 did not solve the problem. Ignition switch did not solve the problem. The next thing I'm going to try is wiring a secondary ground to chassis from the blower control module harness. Probably won't have time to try that until this weekend.
 

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glad you found it
 

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Discussion Starter · #14 ·
Thanks yea, finally, after throwing worthless parts at it, I think I finally found the problem. I couldn't take pics, but anyone looking at the harness could plainly tell there was probably shorting out going on in there. When you drop the ashtray, there's a harness behind the fan/vent switch secured by a clip to a metal plate in the dashboard. All you need is a small piece of 10 gauge wire (Home Depot sells by the foot or something, you need maybe 6 inches if that), two 10-12 AWG butt splices, and a good wire cutter/stripper/crimper. I disconnected the battery, cut both sides, spliced, reinstalled, reconnected battery. The plastic piece holding the harness broke on me, so I used a zip tie. You don't even have to take the full dashboard off, just the ashtray.
 

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hey guys, forewarning this is gonna be a lengthy explanation, but bare with me please.

so about four months ago now, i started having problems with my blower motor kicking in and out, i figured it might have been the dual climate control, so i ended up purchasing one of those. It ended up fixing the problem for a week, and the blower motor went out again. So, after that i went through the electrical lines leading down to the blower motor, thinking maybe no electrical is running down into the resistor/motor itself. Low and behold, no electricity running down to the resistor. So then i traced the wires back up into the car, and found the harness that sits behind the control unit (which was hard as hell to find, and get to by the way). And, pulled that apart. Come to find out that the positive wire ended up charring the plastic and the metal in the harness (on both sides), causing a loose connection. So, instead of trying to find a replacement harness, i just cut the wires on each side of the harness, added a length of wire, and bypassed the harness. And yahoo! There was power going down to the blower motor once again. Well, after I had bypassed the harness, I knew the resistor was going bad, because it was kicking in and out on me. So, i ended up replacing the stock resistor with a replacement. That worked for a good month or so, and as of Friday night, (two days ago) I was having the same problem once again, where my blower motor was kicking out. I figured it was the blower motor itself, so i went and got that replaced, and it worked up until this morning. Where once again it didn't turn on right away, and if it did it would cut in and out. So now im pretty sure that it's the blower motor resistor again.

If you have read this whole explanation, I appreciate it. But, my question is;


Given everything i have done to try and troubleshoot/fix this problem already, what would cause my blower motor resistor to keep failing like this?

And how would you suggest I fix this issue (cheaper the better, economy is hard right now).



COULD YOU ALSO SEND YOUR REPLIES TO MY EMAIL, SO THEN I KNOW I GET THE REPSONSE
[email protected]

Casey
 

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Thanks for the documentation of the trouble shooting you did on the blower issue. I have a 2004 and just started having similar issue. Your posts will be a big help in my trouble shooting, hopefully saving time and $$. I will post back here and let you know how I make out.
 

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my 7th gen 2003 blower was making a racket, wound up being about 10 acorns dropped inside the fan basket. lowered the motor and saw them through the fan blades. wiggled the motor out enough to empty it and back up it went, good as new. not putting the interior panel cover back gonna wait out the winter into the spring cuz I might have to get back under there and do it again. but gonna put up some small bags of moth balls when we park it again in our storage spot off-site

BTW for any moderator - I started 2 new threads when I 1st had the blower problem. 1 last night & 1 today & now I can't find them. also, they don't show up in my list of subscriptions. so that's why I posted in this old thread
 

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LOL why does this stuff always happen in the winter, last year my vacuum line split with the outside vents wide open. LOL
 
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