New blower motor not functioning....must be something else..

[Rohls]

'Ello there!

 

I've got a '92 manche. 75K miles.

 

Couple weeks ago my heat/vent/defrost stopped working.

 

I thought my blower motor went out.

 

I pulled the windshield reservoir, un did the power connector to the blower, tested it and yup, ~10.6 Volts when the switch was in the ON position.

 

I bought and installed a new blower motor assembly tonight.

 

NOTHING HAPPENS WHEN I PLUGGED EVERYTHING BACK IN AND TURNED IT ON. :???: :???: :???:

 

COuld it be a relay? Resistor bank I've heard about? Anything else?

 

Please help!

 

Thanks! :doh: :bowdown: :thumbsup:

 

[Eagle]

What position is the switch in when you try to run it? If it won;t run on slow or medium but will run on full speed, the problem is the resistor pack in the air box (over the front passenger's feet).

[Rohls]

Hi, thanks for the reply.

 

It won't run in any position...so that kinda confuses me.

 

Also, it's only getting 10.6 Volts.

 

The battery is at 12.5...and is fine...

 

I was under the impression the fan need 12V or more to run...right?

[Strokermjcomanche]

Is your truck stickshift ? If so Check and see if the clutch master cylinder isn't or hasn't leaked on the fusebox . Also check to see that the blower fuse has power and isn't blown .

[Rohls]

Is your truck stickshift ? If so Check and see if the clutch master cylinder isn't or hasn't leaked on the fusebox . Also check to see that the blower fuse has power and isn't blown .

Thanks, yup it is the 5-speed.

 

I just replaced the clutch master...thrice! POS, but that's a different topic.

 

I'll check for the fluid drippings, but I checked last week and it was fine.

 

Plus, if I'm getting voltage AT THE BLOWER CONNECTOR, the fuse can't be blown.

 

ANy other thoughts?

[Strokermjcomanche]

Are you getting a ground at that connector ?

 

I skipped over the blower connector portion sorry .

[Eagle]

Hi, thanks for the reply.

 

It won't run in any position...so that kinda confuses me.

 

Also, it's only getting 10.6 Volts.

 

The battery is at 12.5...and is fine...

 

I was under the impression the fan need 12V or more to run...right?

Wrong.

 

The fan gets full voltage when the switch is set to high speed. For the other speeds, the power goes through resistors, which reduce the voltage to the fan, which is what makes it run slower. Test the voltage with the switch in each position and you should get different voltages.

 

If you do, your resistor pack is good and the switch is good, so the problem is either the fan, or the ground.

 

Do you have a battery charger? If so, try hot wiring the new fan to the charger and see if it runs. Or -- remove the negative cable from the MJ battery and hot wire the fan directly to the battery. See if it runs. If not ==> the fan is the problem. If so ==> the ground must be the problem.

[Rohls]

 

Hi, thanks for the reply.

 

It won't run in any position...so that kinda confuses me.

 

Also, it's only getting 10.6 Volts.

 

The battery is at 12.5...and is fine...

 

I was under the impression the fan need 12V or more to run...right?

Wrong.

 

The fan gets full voltage when the switch is set to high speed. For the other speeds, the power goes through resistors, which reduce the voltage to the fan, which is what makes it run slower. Test the voltage with the switch in each position and you should get different voltages.

 

If you do, your resistor pack is good and the switch is good, so the problem is either the fan, or the ground.

 

Do you have a battery charger? If so, try hot wiring the new fan to the charger and see if it runs. Or -- remove the negative cable from the MJ battery and hot wire the fan directly to the battery. See if it runs. If not ==> the fan is the problem. If so ==> the ground must be the problem.

 

 

Thanks Eagle.

 

I scrolled through the fan speeds, and I'm pretty certain the voltages changed, but will need to go and verify that again.

 

When connected, the HI fan speed does not work.

 

The fan is brand new. I know there is a small chance it could be faulty right out of the box, but how common is that?

 

>>>I'll try and hot wire the fan to rule that out for sure. TBC.

 

As for the ground, please explain where the I can find the ground to the fan and I'll check that too.

 

Thanks!

[Rohls]

Hi,

 

Please explain where the I can find the ground to the blower/fan....where it terminates.

 

Also, where is the BLOWER RELAY located? How do I test if this is good?

 

I purchased a blower resistor pack to rule that out....should be here in a couple days.

 

Thanks!
 

[Eagle]

If you have voltage to the fan connector with the switch in all positions, the problem isn't the resistor pack. Even when the resistor pack blows its internal fuse, the fan will run on high. Have you tested the fans (old and new) by hot wiring them directly to the battery? Do they run?

 

If they run, and you have voltage to the connector, then the only thing left is the ground connection.

[Rohls]

If you have voltage to the fan connector with the switch in all positions, the problem isn't the resistor pack. Even when the resistor pack blows its internal fuse, the fan will run on high. Have you tested the fans (old and new) by hot wiring them directly to the battery? Do they run?

 

If they run, and you have voltage to the connector, then the only thing left is the ground connection.

Thank you Eagle.

 

Where is the most common ground for the motor located? Do I simply follow the ground from the motor to...? I'm sure it will dissapear into a harness somewhere and then I won't be able to find it....

 

Thanks for the help! :bowdown: :thumbsup: :rotfl2: :cheers:

[Eagle]

Why don't you first verify that the problem is with the ground, by hot wiring the blower motors and seeing if they run?

[Rohls]

Alright...went out there today to do some tests....

 

1) The motor is good. I used the truck's battery to jump the blower; IT SPUN UP FREELY AND WELL.

2) With a multimeter attached to the connector, I switched the speed selector into the low, medium and high positions. The voltage changed slightly from 12.5 to 12.6

3) There is no power at the FUSE BOX at the BLOWER FUSE. IS this normal? i don't think so. The fuse IS NOT BLOWN, I use a tester light and get nothing at the pins where the fuse is connected....what's going on? IS there another blown fuse somewhere else? How it there voltage at the connector where the motor plugs in, but nothing at the blower fuse?!?

4) i tested the MOTOR GROUND as well as I could...is is connected to various parts of the frame and negative of the battery...

 

ANy help would be great....

 

Thanks...!

[Eagle]

You have a real mystery. The voltage should change more than 0.1 volts through the range of speed settings.

 

Does all wiring appear to be factory?

[Rohls]

Thanks...yeah, it appears to all be stock.

 

I ordered a new resistor pack to give that a whirl.

 

Is there a 'blower relay' or similar somewhere?

 

What are all those other electrical components up underneath the dash on the passengers side? Anything I should be concerned with?

[HOrnbrod]

Is there a 'blower relay' or similar somewhere?

 

There is no power at the FUSE BOX at the BLOWER FUSE. IS this normal? i don't think so. The fuse IS NOT BLOWN, I use a tester light and get nothing at the pins where the fuse is connected....what's going on? IS there another blown fuse somewhere else? How it there voltage at the connector where the motor plugs in, but nothing at the blower fuse?!?

There is no blower relay.

 

Gotta ask: Is your IGN switch set to RUN when you are doing your measurements? If not, there will be no voltage to the BLOWER FUSE.

[Rohls]

 

Is there a 'blower relay' or similar somewhere?

 

There is no power at the FUSE BOX at the BLOWER FUSE. IS this normal? i don't think so. The fuse IS NOT BLOWN, I use a tester light and get nothing at the pins where the fuse is connected....what's going on? IS there another blown fuse somewhere else? How it there voltage at the connector where the motor plugs in, but nothing at the blower fuse?!?

There is no blower relay.

 

Gotta ask: Is your IGN switch set to RUN when you are doing your measurements? If not, there will be no voltage to the BLOWER FUSE.

 

Yup, ignition is on...I'll check it tonight again...

 

http://postimg.org/image/voftmubqx/

Then what's this thing? Just A/C?

[HOrnbrod]

http://postimg.org/image/voftmubqx/

Then what's this thing? Just A/C?

I don't where that picture is from, but there is no blower motor relay. There's one for the A/C clutch, and one for the aux cooling fan though..........

[Rohls]

 

http://postimg.org/image/voftmubqx/

Then what's this thing? Just A/C?

I don't where that picture is from, but there is no blower motor relay. There's one for the A/C clutch, and one for the aux cooling fan though..........

 

 

 

Ok...

 

Update:

 

1. Put in a new resistor pack; didn't do anything. Blower fan is still not spinning :hmm:

 

What else is in this circuit that I could replace?

Does anyone have a diagram for circuit?

Should I get a new fan switch? How do I test mine now?

 

Where does the ground for the blower fan terminate? I know it's to the frame, but HOW DO I TEST more than resistance testing with a meter?

 

I don't know what else to try here... :???:

[HOrnbrod]

The blower switch is p/o the dash HVAC assembly. I think the next step is to pull the dash bezel then the HVAC control assembly and inspect it. Make sure 12V is present on the harness connector and is mated properly, and check that the switch has continuity in each position with your ohmmeter.

[Rohls]

The blower switch is p/o the dash HVAC assembly. I think the next step is to pull the dash bezel then the HVAC control assembly and inspect it. Make sure 12V is present on the harness connector and is mated properly, and check that the switch has continuity in each position with your ohmmeter.

I did pull the switch/selector/HVAC assembly from the dash. No visible damage...I didn't have a chance to put a meter on it. I will do this over the weekend.

 

Where specifically should I look for continuity...? Each position (HI/MED/LOW) on the switch?

 

If it helps, there is a sound like a relay half-way clicking coming from the resistor pack area (under/in the glovebox) when I switch the HI/MED/LOW fan selector...kinda strange.

 

Thanks for the help!

[Eagle]

I disagree about pulling the dash switch, and I told you changing the resistor pack wouldn't fix it. If you have voltage at the fan connector, and the fan motors run when hot-wired, the ONLY possible cause of the problem has to be the ground. There are only two wires here -- power in, and power out. You have verified that you have power in, so the problem has to be on the power out side.

[HOrnbrod]

I disagree about pulling the dash switch, and I told you changing the resistor pack wouldn't fix it. If you have voltage at the fan connector, and the fan motors run when hot-wired, the ONLY possible cause of the problem has to be the ground. There are only two wires here -- power in, and power out. You have verified that you have power in, so the problem has to be on the power out side.

 

He said he had no voltage at the blower fuse.

[Rohls]

I disagree about pulling the dash switch, and I told you changing the resistor pack wouldn't fix it. If you have voltage at the fan connector, and the fan motors run when hot-wired, the ONLY possible cause of the problem has to be the ground. There are only two wires here -- power in, and power out. You have verified that you have power in, so the problem has to be on the power out side.

 

Please tell me where the motor ground terminates and I will test. From what I see the ground (negative/black) wire going to the connector dissapears into the harness...

 

I test the ground wire at the connnector to the chassis/frame of the truck and there is a connection. I'd have to double check, but pretty sure in the 0.2-0.3 Ohm range...ie just fine.

 

The motor has voltage at that connector, so from what I understand that means it has a path to ground.

 

There was no voltage at the fuse because the resistor pack wasn't present. not exactly sure why, though not gonna worry about it at this point.

 

Thanks again for the tips.

[HOrnbrod]

There was no voltage at the fuse because the resistor pack wasn't present. not exactly sure why, though not gonna worry about it at this point.

The voltage to the blower fuse comes directly off the IGN switch. The blower resistor pack has nothing to do with whether it's present at the fuse or not.