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Discussion Starter · #1 ·
OK, here's the deal. My AC and heat work great. Trouble is, the connection on the engine side of the firewall, that I'm guessing gives everything power, keeps coming loose. The whole assembly attaches just fine, but only if you get them just right. And by the time I've gone half a mile down the road, it's jiggled loosed again and I have nothing come from the heating/AC unit. And, as I found out this morning going to work at 5:00 am, no defoggers either.

My thing is, I'm not sure where to get the parts. I can easily do the work, I'm just not sure where to find them. I've checked a couple of places with no luck.

Any ideas?
 

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Discussion Starter · #2 ·
Well, here's a new wrinkle. I went out to fiddle a bit and try to narrow down exactly what I need to do. I attached the connection, started the engine and made sure everything was working as it should before putting a little bit of electrical tape on it to hold. After a few seconds I could hear a spark or two and a tiny bit of smoke.

Needless to say, I disconnected it and left it at that.

Anyone know why this would happen?
 

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Discussion Starter · #3 ·
OK. Here's the inevitable update. And an apology. Sorry again for asking for help only to figure it out. I'm good at fixing and programming computers, not working on cars or trucks. But, fundamentally, most of these problems are electrically related anyway.

So, I looked up several things that involved the heater and AC. I narrowed it a down to the blower, well, because that's what it sounded like. I found mention of the blower resistor block. Easy fix really. So I looked up the part on eBay and found what the construction is. Then I pulled the one out of the truck. I saw the problem right away. The two resistor coils were EXTREMELY close together. Which explains why it only sparked and acted up while the engine was running or driving. So I moved them apart a bit to make sure they wouldn't touch.

Bingo. Problem solved. The two coils touching would cause an arc, then the spark and the connector would work loose.
 

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Glad you found it and fixed it.
Perhaps your write up will help someone else.
 

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Discussion Starter · #5 ·
Hopefully it will. I was on eBay ready to click "buy" when I thought it may be a good idea to take it out of the truck (only two screws) and inspect it. Found the problem and did my little thing, and it was fixed. Saved $9.50 by just looking in there. Like I said, I'm A LOT better with computers. But like everything else (like how I learned how to do drywall last year) I go to google and type in what I'm looking to do and add "do it yourself" to the end of the search.
 

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those resistors are known for burning out; and $9.50 is high for a new one; mine died going down the road one day I stopped by a Car Quest (not even my "normal" store, I was 40 mi from home) and without the better discount I get from my "home store" I paid $7.99 tax incl. I have since put a pretty big order into RockAuto and ordered up a spare; if my 90 Dakota was an indication, I will go thru at least 1 more while I own this 94. At Rockauto it was like $5.
 

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Well, here's a new wrinkle. I went out to fiddle a bit and try to narrow down exactly what I need to do. I attached the connection, started the engine and made sure everything was working as it should before putting a little bit of electrical tape on it to hold. After a few seconds I could hear a spark or two and a tiny bit of smoke.

Needless to say, I disconnected it and left it at that.

Anyone know why this would happen?
Obviously, your 15 yr dakota is much too young to be smoking!
You need to take it behind the woodshed and give it a serious talking to! :D

EXPLANATION:
Those wire wound power resistors get quite hot from the blower motor current running thru them..and distort from the heat. Heat distorts nichrome wire, and over so many contractions and expansions, the 3 resistors (M1,M2 and L) touch each other and..you get a spark, as each dropping resistor is a different voltage drop.:rolleyes:

"Call-1 800 HOWZ MY EXPLANATION":D
 

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those resistors are known for burning out; I have since put a pretty big order into RockAuto and ordered up a spare; if my 90 Dakota was an indication, I will go thru at least 1 more while I own this 94.
Yes, it's a good idea to carry a spare, if you use the blower a lot. Just like
a spare tire, spare quart of oil, camshaft sensor, crankshaft sensor, better
quality ball joints, spare bearing hub...spare serpentine belt, spare brake pads
and rotors..and don't forget the tire jack + wheel wrench..you shouldn't leave home without them!
 

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yeah, its rare I dont have an extra set of plugs, wires, cap, rotor, filters, pads and shoes, bulbs fuses valve cover gaskets, and I even try to keep a starter and alternator around for that inevitable late nite issue after the parts stores close; plus who knows what else.... what ever i can get my hands on; it usually gets used on somebody else's vehicle before mine needs it; I'm on the lookout for an A500 or 42RH to rebuild for future needs....
 
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