Blower motor wont turn on - HELP me finish diag plz?

[car_boy_16]

My blower motor doesn't work anymore. The heater controls (push button style) works fine. I took the blower motor harness off and when I press the HI button for the fan on the heater control it puts out 12-volts to the multimeter. So it's getting 12-volts to the blower motor, BUT the motor will not work. Now you'd think the blower motor is shot so replace it, but I checked the blower motor by hooking it directly to the battery and it works fine. What?? So I checked my 7.5v gauge fuse, it was fine. I checked the heater blower resistor and it is partially broken, BUT it does have continuity at the large resistor coil, so that shouldn't be causing my no blower motor condition. So I tested the circuit breaker (breaker said 30 amps, whereas the manual says 40 amps, did I locate the correct breaker, or did I and the breaker is just the wrong specification?) that is next to the heater relay and it was fine.

So I take out the blower motor relay and check for continuity between 1 and 3 and there is none when it specifies for there to be continuity. Every other function of the relay seems to be within spec, except for the 1-3, so by that it should be replaced. So I think the relay is bad and I get this stupid ass idea that I could jump the relay wiring with some wire, so I jump 1-3 and it smells like burning wire so I immediately take the wires out and I check my 7.5-volt GAUGE fuse and it's blown cuz I did that (and with it blown, the temp gauge, and tach will not work, nor will the car shift into OD because it still thinks the coolant is cold). I don't have a 7.5v fuse on me so I'll change that later tonight.

My question is: Would a bad relay (1-3 has no continuity) still allow 12-volts to go to the blower motor wiring harness? And besides that, WHY does the blower motor not work if there is 12-volts going to the harness but it works when I hook it up directly to the battery? I am confused why this happens. Someone please reply! Doctor J?

It's 19 degrees out and snowing and I'm freezing my arse off and my 'new' Subaru Impreza that I bought as a replacement wont start either so I have 1 car with a heater that won't start, and this Toyota that runs and drives but has no heater.

[Dave's]

When you hook it up direct, how well does it work? What's it sound like when you remove power? Smooth, coasts to a stop? Because it's possible to force a somewhat bad motor to run with enough current using large wires, plenty of power and no fuse. However, it should have taken the fuse before the relay contacts. But by jumpering the contacts it did blow the fuse so I don't know. The burning could have been from too small of jumper wire or too much current draw by the motor. Or possibly a short in your broken resistor pack. Sorry, I don't have a schematic for your circuit so I can't guess at much more. Hope someone can give you better advice.









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[car_boy_16]

Originally Posted by Dave's

When you hook it up direct, how well does it work? What's it sound like when you remove power? Smooth, coasts to a stop? Because it's possible to force a somewhat bad motor to run with enough current using large wires, plenty of power and no fuse. However, it should have taken the fuse before the relay contacts. But by jumpering the contacts it did blow the fuse so I don't know. The burning could have been from too small of jumper wire or too much current draw by the motor. Or possibly a short in your broken resistor pack. Sorry, I don't have a schematic for your circuit so I can't guess at much more. Hope someone can give you better advice.

It seemed to work just fine when I hardwired it to the battery, it actually kicks somewhat so I have to grip it before I touch the last wire to the battery post. Though, I wasn't really paying attention to how it seems when coasting to a stop. The wire I used to hardwire it wasn't large, it was actually smaller than the wires in the factory harness, but yeah it was a direct battery-to-motor setup so I'm sure it had more power running to it during the test.

Anyone else have any ideas or insight? I still don't understand that, assuming the motor works (maybe Dave is right though), why would the motor not turn if the harness itself was getting 12-volts to it? Could the relay, with it's no-continuity between 1 and 3, be causing all this but still allowing 12-volts to the harness? Argg

[white90dx]

First, I'm going to assume you are talking about the "Heater Relay" (5-pin) not the "Blower Control Relay" (8-pin). The Heater Relay gives power to the whole system while the Blower Control Relay controls the speed of the blower.

It is possible that the Heater Relay has a large amount of resistance on the switch side when it is in the 'on' position - enough to allow 12V to get to the blower to read on the multimeter (with no blower plugged in) but not enough to get the motor spinning.

Oh, and pins 1-3 shouldn't ever be shorted. You just connected power to ground... That is the coil connection for the relay and should be at least 10's of ohms (won't show as continuity on a multimeter when put on that setting).

Have you tried replacing that relay yet? When you test the blower, make sure you test it on the high setting - later you can fix/replace the blower motor resistor...

-Charlie

[car_boy_16]

Originally Posted by white90dx

First, I'm going to assume you are talking about the "Heater Relay" (5-pin) not the "Blower Control Relay" (8-pin). The Heater Relay gives power to the whole system while the Blower Control Relay controls the speed of the blower.

It is possible that the Heater Relay has a large amount of resistance on the switch side when it is in the 'on' position - enough to allow 12V to get to the blower to read on the multimeter (with no blower plugged in) but not enough to get the motor spinning.

Oh, and pins 1-3 shouldn't ever be shorted. You just connected power to ground... That is the coil connection for the relay and should be at least 10's of ohms (won't show as continuity on a multimeter when put on that setting).

Have you tried replacing that relay yet? When you test the blower, make sure you test it on the high setting - later you can fix/replace the blower motor resistor...

-Charlie

Thanks for the reply, I was getting scared that nobody was going to. This might sound like a stupid question but I have tried doing online searches of Advance Auto and Napa and I just cant seem to find a listing for a Heater Relay (and yes that's what I meant by 'Blower relay', sorry). Where should I go to get one? Alternately, is there another relay in the car that I can swap with the heater relay to test and see if it's a bad relay? Also, what do you think of my circuit breaker being a 30-amp when the book states it should be a 40-amp? The c/b worked for years before the heater stopped working, so I don't know...

Can you go through the 1-3 posts on the heater relay again, I'm not sure I follow entirely.

Thanks for the help, Charlie, I appreciate it more than you might think.

[white90dx]

I had another thought here... (and I'm not sure if you will be able to test this easily)

Can you test the voltage at the blower motor with it plugged in and the fan on the highest setting? If it is less than 12V or so, then it is one of the relays or other parts of the system. If it is 12V and the motor doesn't turn, then its the blower motor.

As for the relay... Pins 2 and 4 should measure <1ohm when the relay is pulled out of the car. Pin 5 should not have any connection with any other pin. Pins 1 and 3 are the connections to each side of the coil that controls the relay (a little electromagnet). If you apply 12V accross those two pins (orientation doesn't matter) then the relay should click and pins 4 and 5 should now be connected. There should never be a connection between either pin 1 or 3 and any of the other pins on the relay. If the relay clicks and continuity changes from 2-4 to 4-5, then the relay is working.

If it is the relay, it might be a dealer only part (I'm not sure). Check RockAuto to see if it is listed in their catalog. If not, the Toyota P/N is 88630-20020 and its about $45 from 1st Toyota Parts (ouch!).

-Charlie

Edit... RockAuto has the relay for $13.09!

[car_boy_16]

Wow I looked on RockAuto and I didn't find it, guess I'm getting a bit blind. Hey thanks for all the support, I really was about to drive the car off a cliff out of frustration. So I had already ordered a blower motor prior to this thread cuz I was sure that's what it was cuz of the way the motor stopped working the way it did. Before I work tonight I picked the motor up from the parts store and for the hell of it I just hooked it up quickly to see if it would work -- IT WORKED! So Dave was right on I guess.

Edit: damn that fan wheel was a Btch to get off the shaft!

Thanks for the help Charlie and Dan.

Now I just have to go out there and put it all back together before my fingers lose feeling lol