Heater Blower Motor Information So, after searching a million threads and asking a million questions I finally got the information I needed. But it took a very long and rather boring time to do this so I compiled as much information and pictures as I could concerning the Heater Blower Motor, Relay, Resistor, and Power Connections. Some of you might be getting your hopes up, thinking this will have very detailed information with diagrams etc etc. This is just a basic break down for the basic things you need to know, most of you will already know these things, some won’t. First, the problem. My own personal problem was my heater blower motor wasn’t working at all. I took another motor out of a 87 and hooked it up and it didn’t work either, so I bought a brand new motor and hooked it up, still nothing. Problems will vary, this should help in most cases. A couple things you need to know are: A-To test the motor outside of its environment you have to have it GROUNDED as well as have power run to it. Otherwise it won’t spin at all. Make sure when you do this you really hold onto that motor, it can jerk out of your hand before you have time to react (its easier if the fan wheel isn’t on there but you can do it either way). It’s a good way to know whether your fan is good or bad, and it will eliminate possible problems. B- For those of you that don’t know where the fan lies, it’s on the passenger side of the engine bay, back against the fire wall. It will have two wires running into the back of it, one purple, one black. Purple is power, black is ground. P.S. Pictures to come...

C- You may have heard of the blower motor resistor, and that if faulty, can cause heater fan problems. I will post a picture showing where the resistor is. Its held into the air conditioning box by 2 screws that are easy enough to take out. Be careful when pulling the resistor out, on the underside of it are 3 different coils that control the lower 3 speeds for the fan, you don’t want to damage them. I’m not sure how to tell if the resistor is bad, the most obvious would be to make sure nothing is burnt, fried, or melted. There is a way to test it with an ohm meter I’m sure, but I do not know how. Maybe some members might post any information they have on that subject?

D- Another item of interest is the relay; it is also bolted onto the air conditioning box, but doesn’t have any internal parts within the box itself. Two screws hold it into place. You can follow the purple wire straight from the blower motor to the relay, again, I’m not sure how to check whether it’s bad besides the basic look over. I would just advise taking it apart and dusting it off, possibly brush it with a wire brush to clean it up a bit.

E- Something I found out while searching for any reason why the fan wasn’t working was this; if you follow the purple wire to the relay you will also see a thick red wire that is the raw power from the battery, follow that red wire. It should go over the AC unit heading towards the drivers side, about the time it gets to the passenger side valve cover you will find one, possibly 2 black or gray connectors. They are a factory F up that are completely useless and in the end just cause problems. These connectors tend to be burnt to ashes in most everyone’s vehicle, though there are the exceptions. Cut these stupid connectors off and use a HEAVY DUTY slide terminal, (preferably the insulated type), and reconnect the wires.

Now this isn’t the only connector that does this. Take off your HVAC control head from the dash; find the “mode” switch and the wires coming out the back. There should be 4 if I’m not mistaken; one should be green, one another color I don’t remember, a brownish one with a white strip, and a solid brown one. The solid brown wire should be all the way over on the left side on the set of wires, follow that wire anywhere from 8-15 inches into the dash, (its easier if you take your stereo/radio out, I know it can be a pain, but it may just slide out of the way, depends on how you rigged it up), anyway, follow that brown wire and you will come upon another one of those black or gray connectors, cut it, strip it, replace it. This one can kind of be a pain in the *** because of its location. This wire controls the entire HVAC subsystem so it’d be wise to check it.


On a side note, I did all of these things and hooked the motor back in and everything to it and still had nothing, in a final act of desperation I attached a wire from the negative terminal on the battery to the negative tab on the motor, it works fine now, but I don’t have the high speed setting, I don’t know if any of it helped but I know for a fact that it has been other peoples problems and it worked for them, it has to be because of something in the relay but at the moment I’m just glad to have a heater.

Another thing you should know is when I went to start the car after all this it had a click and clunk and it wouldn’t turn over. Actually, I didn’t get any power to anything after that, kind of frightening huh? So I went back to the engine bay and wiggled a couple of wires, took the power off the battery then hooked it up again, it started up the second time like nothing happened. So if this happens to you just do that and don’t freak out.

I hoped this helped in some way people.

Pictures of underdash connector and fix...

Good job, man!! I going to do mine as well. Too bad we don't think to do this in the summer time!!

Just a question...what is that blue box?

to tell you the truth i havnt the foggiest idea lol, im going to assume its just another quick connection for the steering colum or lights or something, idk.

It's the courtesy light delay module, and it's light green.

To people who find this in the future, please dont use wing nuts to splice large wires. What works in a house is not ideal for the harsh conditions of a car

i was gonna say the same thing. at the very least use som crimp on butt connectors. theyre only a few bucks for a pack of them at the auto parts store

You can get a soldering iron for <$10 and fix it the right way

Haha, at 16 guys, you work with what you have.

Being young means you get to learn first hand the proper tool for the job. Using something on hand to rig it is not good practice

I'm not saying do what I did, it's not like that anymore because I have proper funds now. but at 16 with no money, it's either go without a heater in the middle of a Wyoming winter, or fix the damn problem.