Heater fan failure

[Grandavi]

Something odd happened yesterday and I'm wondering if its going to be very hard to troubleshoot.
When I I turn on my ignition the temp control lights are bright, but when the engine starts, the climate control lights get very dim and the fan has stopped blowing.
Dead blower motor?
Fuse is fine. I am wondering if I can access everything to check wires, etc.. By taking off the glove compartment or if I have to disassemble the dash to troubleshoot. I do have another climate control but I highly doubt these ever fail... So I think it's either a wiring issue or the blower.

The blower worked good about a week ago, although it would blow cool air while idling...
The temp gauge never fluctuates once it heats up.

Thoughts?

(This is my 90 7mgte a/t, not the 88)

 

[kanji1jz]

Does it do it only at high speed, low speed? Have you tried banging on the motor to see if it would start back up again? It sounds barbaric, but if you try and hit the motor with the side of you fist and it comes back on you know that it is the motor itself. If it does not it may be a blower motor resistor going bad, or a climate control unit.... If the fan speed is on anything but high speed, try putting it at high speed and see if it still works. If so, then definitely a blower motor resistor. If not, then I would say check the wiring and maybe try installing your other climate control unit. Any other questions let me know.

 

[Grandavi]

Fan doesn't run period. The switches light up but the fan doesn't run, when I start the engine the lights go out on the climate control. I will try the replacement... Mine is metric and the replacement is in F.. But I grew up with imperial..

 

[Grandavi]

Before I start tear down and the hunt for the fault, is the blower motor easily accessible or will the entire dash have to come apart? (just need to know so I can situate the car in the right spot depending on what I am going to have to do.

As a note, I replaced the battery this month, and then replaced the alternator with a 87 alternator (70 amp as opposed to the original 80 amp that was on it). I have always had a tail light light going on everytime I tapped the brakes, but the lights are all functioning (except the interior... some of the leds in the dash are very dim or dead). The tail light will sometimes go on and stay on, and sometimes just stay off, but will inevitably come on when I hit the brake pedal. I was assuming it was a short in the tail light wiring (a loose ground) which I didn't plan on fixing until I had a new antennae (mines stuck mid-level) and seals for the tail lights.
There is a Viper alarm in the car but I dont have the fob for it (PO had it installed, not sure what all its capabilities are). I can see the module right above the fuse box and the antennae for the remote is right behind the rearview mirror, but there is no "alarm horn" in the engine bay. This is probably my biggest concern after I get the heater fan working because I have no idea how well the stereo and remote/alarm installation was done. So far, most of what I find in this car has been mickey-moused and I have to redo it.

For the immediate future, I just need the blower running as I have to be able to see to drive it.. lol. Where I live, you need the defog capabilities year round. I dont normally drive a supra in winter, but my 88 MK3 cost so much to upgrade/replace the engine, I had to force the 90 into DD service..

 

[kanji1jz]

I mean I would still try pounding on the blower motor before I replaced anything.. I have seen some crazy stuff in my days of working on cars (which are many and very, very long) and sometimes you can have a draw of voltage by a seized blower motor and sometimes the pounding on the motor while the fan speed is on can make the brushes inside the motor unstick and possibly work again. Again, the best thing to do is pinpoint the problem. If you have a way of applying power to the blower motor you should be able to access the plug fairly easily and I would just try and penetrate the insulation on the positive side wire and apply 12 volts to the motor and see if it spins... If it does, then you know to look elsewhere; if it doesn't, then you know that it is the issue. Good luck! Keep me informed of what you find and I will do my best to help. I hope this is good info for you.

 

[hvyman]

If you have access to a power probe can easily add power and ground to the motor to see if its bad.

 

[Poodles]

From what I can remember, yes, it's easy to get to.

http://www.cygnusx1.net/Supra/Library/EPC/291420/catalog.aspx?F=8712&P=1 kinda explains it.

 

[Grandavi]

Thanks, will try that. I am pretty sure I can access the motor by just taking off the glove compartment. The climate control seems to be working fine. Funny how the LEDs on my dash are weak compared to my 88. If I don't sell this car I am going to have to deal with those...

 

[3p141592654]

You really need to diagnose this in an organized way. Start by checking the 40A heater CB, and then the heater relay. See the following chart. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AC&P=15

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=140

 

[Grandavi]

Well, I got a proper electrical tester and tested the power to the fan. It was 12 V to the High mode, 0.1 V to the Med, and 0 V to the Lo.
I bought a new blower motor and hooked it up (not knowing if I should be going clock-wise or counter clock-wise) and tested it outside of the housing. I put my hand over the top to see if it was "sucking" or "blowing" to find out if I had the polarity correct and will not do that again.. lol. I tapped the blower fan and it took off a piece of fingernail and some skin on my fourth finger... ouch! I think you could chip wood in that fan...

So, as a note for those who arent sure of the direction, I put it into the housing and then checked for polarity by feeling how much air came out of the vents (it was only working on High). Anyone know what the correct direction is? I cant see it spin to check now but it should be noted somewhere.

It works now in High and Medium (not sure if a resistor is gone) but if you idle it blows colder (which may mean my thermostat is sticking open). Now, though, my passenger side window wont roll down. I dont know if I pulled a wire by accident or forgot to plug something back in. Its a 1990 Auto, so I hate to move the ECT computer out of the way to get the blower motor out.

Another note... someone has done this once on the car which is very annoying because they stripped the screw heads. Took me about 3 hours to do a 1/2 hour job... what a pain! Dropped the screw that holds the farthest portion (inside the fender almost) down into the rocker panel by accident so it is only being held on by 2 screws right now.. I think I will just get new screws for it. Had to use a vicegrip to get one out.. and its not fun at that angle.

Question... is the passenger side window a plug or a wire in that area? I had to unplug 4 plugs removing the blower motor, so wondering if maybe I got one plug wrong. It worked perfectly before I started. (I hate that when you put something together nice and neatly only to discover you killed something in between... )

Also, is the Low speed not working a seperate resistor outside of the environmental control box or is the box having issues with it? (I do have a replacement one but its in F, not C)

 

[3p141592654]

The blower resistor network is attached to the bottom of the plenum after you remove the trim panel under the glove box. It is held on by one or two screws. Very simple repair if that is your problem.

 

[Grandavi]

are the resistors universal or do I have to get the OEM replacements?

and any idea why my pass window wouldnt roll down now that I have the heater working? Is there a junction in there that I could have unplugged?


odd that I didn't get any voltage out of the medium range, but it works fine now...

 

[Grandavi]

Well, I went back in (amazingly easy the second time) and found that I had missed a plug which is why my window wasn't working. They pack a lot of electronics into that area.
Going to just ignore the low fan speed because I dont really use it anyway.

Next job... AC on my 88.. gotta get a new compressor...

 

[Grandavi]

Can someone tell me.. which direction does the blower motor go? Clockwise or Counterclockwise?

I think its counterclockwise... just want confirmation...



Just as a reference for later on.


Deleted my posts past this point.

Can someone confirm the fan should be working in a counterclockwise rotation? Thanks!