10secondhopeful

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...

10secondhopeful

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?

10secondhopeful

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.

10secondhopeful

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.

10secondhopeful

Pictures of underdash connector and fix...

donnis618

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

Sgt. 56

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

10secondhopeful

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.

scubasteve

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

Pocket

iTrader: (24)

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

travis401

iTrader: (1)

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

Pocket

iTrader: (24)

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

10secondhopeful

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

Pocket

iTrader: (24)

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

10secondhopeful

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.

Rumble Complex

Hey 10secondhopeful, thanks for taking the time to share all of this. Now I know what to look for too. Oh, I remember being 16 too ;-)

schalid

I had the same problem. Replaced motor, resistor and relay. I used a wire tester and a wiring diagram and had power to all correct wires when fan control was put in the positions. I finally took the ground wire off the blower and ran another wire from there to a bolt on the inner fender and then it worked. It worked on speeds 1,2,3, but not on hi. So I found in another part of this forum to put a jump wire from the purple wire of the blower to the orange wire of the relay, and then hi works. Dont understand why all this is necessary, but it now works.

James beaver

Is it possibable to by pass all the relays and resistors and run a toggle switch straight to the fan? I have power from fuse box to a/c selector switch and to switch, but nothing to the fan(purple wire going to fan) ran new ground and still nothing.

10secondhopeful

Goes to show that I'm not on TGO as often as I use to be. In the end, that was my problem as well, the ground. I think it was at least, it was 4-5 years ago. Glad you got it fixed.
C.

So you have power running from the fuse box to the switch, do you have power running out of the switch? If not, I'd bet your switch is junk, replace it. I'm sure you could run power straight to the fan through a toggle switch, but you'd probably only have 1 speed, HIGH, and it probably wouldn't be good for the blower motor. Best idea would be to find a junked third gen and take what you need out of it.

C.

John in RI

iTrader: (167)

To people who find this in the future; That is a LIGHT DRIVER MODULE. It was used in-line between the ECM and the Check Engine light on all factory Carb cars.

DerrenZ

For future reference, in both these cases the high speed wasn't working because the high speed relay wasn't working. But not because the relay was faulty.

When you bypass the ground wire for the blower motor, you may also rob the relay of it's ground wire so it can't function and deliver power to the purple wire on the highest fan setting.

So if you have provided a substitute method of grounding the blower motor, you may need to provide a substitute method of grounding the high speed relay so you won't have to jump the purple to orange as mentioned above.

Also, jumping the orange to purple is dangerous since the orange wire should not feed the purple on high speed fan operation. That's what the relay and the thicker red wire are intended to do. The orange wire is not correctly sized for the load.

mmorley1024

Relays are installed in factory systems to help with loads, you can by relay holders and relays at parts store and make your own harness if needed. Thanks.

Hello, Michael

I'm having a problem where my blower only works on high. I replaced the resistor, thinking that was the problem, but it wasn't. Is it possible it could be the relay?

Liboicl

High is the only setting that uses the relay. If you want, I can post a schematic diagram for you. On all other settings it goes straight to the resistors from the control panel inside.

Hello, Michael

Thanks, but I figured it out last night using the diagram in my Haynes manual. The relay is bad. Looks like I have to order one cuz none of the parts stores around me seem to have them in stock. Thanks anyway for offering to post the diagrams.

firefox7518

Hi

I have the same issue like Michael. My fan is only working on the high setting. The realy is clicking audible so I think is working also due to the fact the blower is running on high setting. I drive a 89 GTA with the "more modern" control unit. I don't have ***** to turn to select speed and venting. I have the version with buttons. (sorry i don't know how to call it on english)

Besides the high speed relay I have a second one right beside it. If I take it out, I don't have any power to the control unit. Does someone know what exactly this smaller relay is controling? I can't find any schematics.

Anyway, I already exchanged the resistor pack but still no joy. I have power coming to the resistor on on the different speed settings so that looks ok but still the fan is only running on high setting.

Any suggestions what I could test or try?

Thanks a lot
Andi

John in RI

iTrader: (167)

Does your GTA has a digital dash in it ???

firefox7518

Yes exactly. It has the digi dash.

firefox7518

Some observations:

Red Wire does have 12V constant all the time which is good.
Orange wire has 12V when going to high setting
First violet wire has 12V going to the resistor as soon as I turn on the ignition to on. This wire goes to the resistor pack.
The second violet wire does have power 12 when I unplug the blower. If i plug in the blower there is 0V on this wire and only 12V when I set the blower to high setting?!?
I only have one violet wire going from the blower to the high speed relay. There I have two. I thought the relay should switch between Red Wire and the violet wire coming from the resistor to drive the spped from the blower? Am I right with this conclusion?

Is the blower or the relay dead if I only have power on the violet wire going to the blower if I unplug it?

If it is the relay can I use an other automotive relay to achieve the same functionality like the OEM one? The things are hard to find here in Switzerland and I already ordered some relays but the were not the correct ones. A standard relay would have post 30, 87,87a, 85 and 86 and I think with such a stand one the funtionality is not achievable. I maybe need 2 relays to do the same?

Ideas?

NINÅ

John in RI

iTrader: (167)

Yup, the smaller relay is called the "Low speed Blower Relay"

When the digital dash Firebird blower fan only works on the HIGH setting the shop manual says:

Measure voltage @ disconnected HIGH speed relay

Ignition in RUN
AC control set to VENT
Blower speed on HIGH

Red = Battery ( pin D )
Orange = Battery ( pin C )
Purple = Battery ( pin E )

Sounds like this is what you found when probing the wires - double check to be sure.

The second for the HIGH speed relay test is this:

Ignition in RUN
Negative battery cable disconnected

Measure from Black to ground; 0 OHMs
Measure from Purple ( PIN 'A") to ground; Approx 3 OHMs.

** If voltages are correct and resistences are correct, but blower doers not operates or operates all the time,.... replace Blower Relay.


There is also a test for "No Low or Meduim Speed" operation.

Measure at disconnected Blower Motor Resistor plug

Measure between A&C; 1.5 +/- 1 OHM
Measure between C&D; .7 +/- .5 OHM
Measure between D&B; .2 +/- .1 OHM

If you don't get those readings, replace resistors.

firefox7518

Thanks a lot for your help.

I did the test you've mentioned John but I'm a little bit lost with this setup.

This test looks ok. It had less than 3 ohms so the purple wire is not acting as an additional resistor.

Do you have a diagram to show me the position of A,B,C and D? It's a brand new resistor and I also measured the resistance from the old one to the new and they were almost identical. I also see voltage drops slightly when I measure on the purple wire going to the blower. And I'm back to my question. Why do I see 12V or less on the purple wire going to the blower but only If it is not plugged in to the blower? Could it be that the blower has to less ground to operate on the low speeds and only works accidentally in high?

Could someone explain me the functionality of the smaller "low speed" relay? How does it interrupt this circuit? I have 2 black/white wires going to the resistor plug, from there ones goes to this small relay and one goes from the resistor plug into the harness which goes into the cabin I think. Then I have the purple wire which goes obviously to the high speed relay. Then I have the speed wires coming from the selector of the HVAC control unit.

When the blower is set on high I still have full power on the resistor circuit?!? How do I have to measure that?

Thanks a lot for your help guys! Really appreciate that!

John in RI

iTrader: (167)

Here are the wiring schematics for the 88 GTA Electric( digital dash ) Heater/Blower....






I found the pin-out for the Resistors too:





If understand what I see,.... The controller gets it's power from the LOW speed relay in any setting other than OFF to get the ball rolling. Once the Controller is ON voltage gets sent thru the Brown/White wire to the resistors and back to the control head. ( you thought these were Black/ White wires )


The Brown/White from the low speed relay will power the fan @ low, when turned to MED1 the TAN wire will also feed the resistors, M2 and the LT BLU circuit also feeds the resistors and in each case the HIGH speed relay is fed power thru the PURPLE on pin 'C' & the relay feeds power to the Blower thru PIN 'A".

With the setting on HIGH speed TAN and Lt BLU are not used and the controller feeds the HIGH speed relay thru ORANGE. The relay closes and power is sent directly from the fusible link (RED) and out thru pin 'A' of the relay to the blower.

Seems like:
the MED1 blower setting you should see voltage on the TAN wire at the resistor

the MED2 blower setting you should see voltage on the LT BLU wire at the resistor

ONLY in the HIGH blower setting should see voltage on the ORANGE wire at the HIGH Speed Relay.

If any of those 3 things are NOT true than I would suspect the Controller.


There's no "System Operation" section in the manual - just the 2 troubleshooting tests that I posted earlier.

firefox7518

Thanks a lot for the schematics!!! That's much of a help. I checked the TAN, Lt Blue and orange wires and I have voltage there as required.

So I'm completely lost for now. The relays are working, If I turn of the Vent by selecting of, there is no Power to the lo power relay. If I turn it on I have power going to the resisitor and also on the tan and lt Blu wires. I also have Power going out to the high speed relay on the purple wire and I also have power on the purple wire going to the blower BUT as long as the blower is not plugged in. As soon as I plug in the blower the Voltage drops to zero on the purple wire going to the blower. I measured that on the high speed relay.

So question is, is the high speed relay faulty even if it switching to high speed or is the blower somewhat dead even it runs perfectly on high speed with any strange noise and good blowing power out of the vents?

What do you think? Especially the situation that I have power on the purple wire as long as the blower is not connected to it? I never saw something like that.....

John in RI

iTrader: (167)

I'd say yes,... it's very possible the HIGH speed relay is bad. It should switch the power supply for the fan from the Red wire when on HIGH speed to the Purple resistor wire (PIN B) when the controler is switched to lower speeds - and VISA/VERSA.

You might have the proper voltage coming from the Resistors to the HIGH speed relay when in all speeds other than HIGH, but if the HIGH speed relay isn't able to complete the "switch" of the power source from RED to PURPLE inside the relay ( possibly due to a bad circuit inside the relay as show below ) you would not get any other speeds.

firefox7518

Thanks. Had some time today to look again. This time I went from the resistor purple wire straight to the blower motor instead of going via the high speed relais and et voilà the blower is working on all lower speeds nice and smooth.

This therefore proofs that the high speed relay is faulty and needs to be replaced.
Searching in Rockauto brings me up the following relay:
DORMAN Part # 85159 {#12101882} 5-Wire A/C High Blower Relay
Relay - Blower High Speed (5 wire) (Only 2 Remaining)

Is this the correct one?

John in RI

iTrader: (167)

Glad to hear you found the 'bug'.

I don't know what the Part number of the relay: Search the numbers off the HIGH speed relay you have now to see if the replacement part is compatable.

firefox7518

There's nothing you can read anymore on the relay so no number to look up :-(

John in RI

iTrader: (167)

The numbers on my GTA high speed relay are 10026578.

wildstar

t

kallark

iTrader: (1)

Thank you all who contributed to this discussion. Helped me fix my heater fan gremlins. The number on my relay was also 10026578. A replacement part is readily available for sale on a certain large online retailer with name that starts with A. Just search for 10026578

Thanks all

spiffiestpengui

Sorry to revive an old thread like this...but I am just curious, isnt it dangerous to take out the fusible link like that and just connect the wires? should there not be an inline fuse at least installed in place of it? I knew nothing about fusible links existence until about a week ago, and I am considering cutting out that connector and putting an inline fuse in its place. I have replaced my relay, and the resistor, and the blower still will not work. if I leave the ground hooked up, and run power from the blower straight to the battery the blower works fine, but only on high..I am wondering if my fusible link also went bad. this has been driving me nuts

spiffiestpengui

Actually I may have misunderstood what was being done there. I thought that you meant your link had burned up, and that the connectors you added were in place of it. I realize now that the part that melts is down lower near the starter, and the connector you were replacing was not where you would even put a fuse. oops

RSFreak

Bringing this back for future generations. My buddy had the same problem on the '86 Trans Am I sold him. After switching out the blower motor, high speed relay and resister pack, it turned out to be a bad ground. Added an addition ground to body at the blower motor and now everything works perfectly.