Blower motor not working

[01saharatj]

Had issues about a month ago the highest setting not working, replaced speed control switch and it started working again. Now, Nothing at all it doesn’t even work in lowest setting. Took apart and tested for voltage to switch and not seeing any voltage to fan speed switch. I tested fuse and it was good. I did notice on the connector to fan speed switch some of the plastic on connector was melted slightly. Not sure what to make of it. I’m Losing voltage from fuse to switch an electrical schematic would be appreciated!

 

[tr21triton]

Look under resources section and you can download the manual for free. Section 8w is wiring schematics if I remember right

 

[B1Toad]

You won't find battery voltage at the fan switch, or at the mode switch as they both switch the negative side. Battery voltage is supplied directly to the blower motor through the blower motor relay whenever the ignition is on. The negative is supplied from a body ground (G202) in the footwell that is connected to a small spade terminal on the mode switch, when you rotate the mode switch the negative voltage along with vacuum operates the various functions but the negative power is also passed through to the blower speed switch which routes the negative current through the resistor pack to change the speeds.

It is not unusual for the connection to the spade terminal on the mode switch to overheat when on high, causing a failure. Is that where you saw the melted connection?

 

[B1Toad]

Here is a thread showing how I fixed mine. You can replace the control unit or fix the bad connection and call it a day but I highly recommend adding the relay if you want it to hold up long term, especially if you use high a lot. https://wranglertjforum.com/threads...o-far-and-my-blower-quits.79113/#post-1573422

 

[01saharatj]

You won't find battery voltage at the fan switch, or at the mode switch as they both switch the negative side. Battery voltage is supplied directly to the blower motor through the blower motor relay whenever the ignition is on. The negative is supplied from a body ground (G202) in the footwell that is connected to a small spade terminal on the mode switch, when you rotate the mode switch the negative voltage along with vacuum operates the various functions but the negative power is also passed through to the blower speed switch which routes the negative current through the resistor pack to change the speeds.

It is not unusual for the connection to the spade terminal on the mode switch to overheat when on high, causing a failure. Is that where you saw the melted connection?

Looks like a slight bit of melting goin on here

 

[B1Toad]

Is that the blower switch connector? If you wiggle it around does your blower work?

 

[01saharatj]

Question where is the the “blower motor relay” located

 

[B1Toad]

Here's what the 2000 model year service manual says:

If you look in the resources section there should be a service manual for your 2001 if it's not the same

 

[FarFire70]

Here is a thread showing how I fixed mine. You can replace the control unit or fix the bad connection and call it a day but I highly recommend adding the relay if you want it to hold up long term, especially if you use high a lot. https://wranglertjforum.com/threads...o-far-and-my-blower-quits.79113/#post-1573422

This.

Back in the (now defunct) JP magazine covered this. The blower motor draws current through the selector switch. As the motor ages, it draws more current and melts the switch.

Put in relays for each selector setting with straight power via the relays from the battery to the blower - each relay activated by each selector switch setting. There is room behind the HVAC controls for the relays - tape them all together.

This way the blower motor resistor takes the brunt of the high current (especially high at lowest setting) and becomes the 'fuse' in the system, rather than the dash wiring/switches...

 

[B1Toad]

This.

Back in the (now defunct) JP magazine covered this. The blower motor draws current through the selector switch. As the motor ages, it draws more current and melts the switch.

Put in relays for each selector setting with straight power via the relays from the battery to the blower - each relay activated by each selector switch setting. There is room behind the HVAC controls for the relays - tape them all together.

This way the blower motor resistor takes the brunt of the high current (especially high at lowest setting) and becomes the 'fuse' in the system, rather than the dash wiring/switches...

I wired my relay to bypass the mode switch, but my blower speed switch still gets full current. Today is the first I've heard of the blower switch itself melting, I thought it was more robust. In light of this new info now I am considering adding another relay just for high. High is when you see most overheated switches on vehicles, some, like old Mercedes, even have a totally separate circuit for high, I remember my old 300D had a metal fuse strip mounted in a little plastic (or Bakelite) box on the fender just for the blower high speed. I'm guessing the current draw on the lower speeds won't be a problem.

I wish there was a way to see that article you referred to.

 

[B1Toad]

As I suspected, the melted terminal on 01saharaj's connector is cavity 'A' which corresponds to the high speed. Might be worthwhile to put a relay on that one, I run on high all the time here in the desert. BTW the switches don't carry the battery power, that goes thru a relay straight to the blower + side. The switches control the - side, so the relay would bring - to the resistor block, not battery power.

 

[LONGJP2]

BTW the switches don't carry the battery power, that goes thru a relay straight to the blower + side. The switches control the - side, so the relay would bring - to the resistor block, not battery power.

If it's running, current will be flowing through the whole circuit.

 

[B1Toad]

If it's running, current will be flowing through the whole circuit.

Of course it is. My point was you can't connect your new relays to battery power (except for the trigger), you need to connect them (pin 30) to ground or the blower won't work.

 

[B1Toad]

@01saharatj did you get yours fixed? After I saw that I decided to put a relay in my high speed line which I did today. I have 2 relays now, the first one bypasses the mode switch with all the blower current and the second one bypasses the speed switch when switched to high.

 

[01saharatj]

@01saharatj did you get yours fixed? After I saw that I decided to put a relay in my high speed line which I did today. I have 2 relays now, the first one bypasses the mode switch with all the blower current and the second one bypasses the speed switch when switched to high.

I was out of town trying to get back into this now . I saw on here some where someone posted a relay into the blower motor speed circuit I can’t find link would someone repost for me please

 

[B1Toad]

I was out of town trying to get back into this now . I saw on here some where someone posted a relay into the blower motor speed circuit I can’t find link would someone repost for me please

In post #4 I put a link to my thread when I used a relay to bypass the heavy current away from the mode switch as that is usually the first point of failure. There is also a diagram in that linked thread showing what to do. I added the second relay today which was a piece of cake since I already had my new, heavy ground wire and my relay coil power right there, all I had to do was tap into those (30 to ground and 86 to cig lighter power) and then cut the brown/tan wire from the blower switch and use the part from the switch to trigger the relay and the other part to relay terminal 87

Note that on the 4 pin relay terminal 30 and 87 are interchangeable, I actually wired mine 87 to ground and 30 to the load. The current flow direction thru it will be opposite of a relay that switches the hot.

You will still need a working switch to send the ground signal to the relay.

 

[01saharatj]

In post #4 I put a link to my thread when I used a relay to bypass the heavy current away from the mode switch as that is usually the first point of failure. There is also a diagram in that linked thread showing what to do. I added the second relay today which was a piece of cake since I already had my new, heavy ground wire and my relay coil power right there, all I had to do was tap into those (30 to ground and 86 to cig lighter power) and then cut the brown/tan wire from the blower switch and use the part from the switch to trigger the relay and the other part to relay terminal 87

Note that on the 4 pin relay terminal 30 and 87 are interchangeable, I actually wired mine 87 to ground and 30 to the load. The current flow direction thru it will be opposite of a relay that switches the hot.

You will still need a working switch to send the ground signal to the relay.

So I kept playing around with the wiring got blower fan to work but the air would only blow through defrost then when I went to mount everything blower quit working again wtf!

 

[01saharatj]

In post #4 I put a link to my thread when I used a relay to bypass the heavy current away from the mode switch as that is usually the first point of failure. There is also a diagram in that linked thread showing what to do. I added the second relay today which was a piece of cake since I already had my new, heavy ground wire and my relay coil power right there, all I had to do was tap into those (30 to ground and 86 to cig lighter power) and then cut the brown/tan wire from the blower switch and use the part from the switch to trigger the relay and the other part to relay terminal 87

Note that on the 4 pin relay terminal 30 and 87 are interchangeable, I actually wired mine 87 to ground and 30 to the load. The current flow direction thru it will be opposite of a relay that switches the hot.

You will still need a working switch to send the ground signal to the relay.

I ordered a relay and connector on Amazon

 

[B1Toad]

Sounds like you're going to need a new control unit also

 

[FarFire70]

Pulled some archives of the JP Magazine article I mentioned before...

Most of the pics didn't survive on the wayback machine but gives you an idea of how this was being address in the DIY community all the way back to 2007.

https://web.archive.org/web/2015012...w-to/electrical/154-0710-jeep-fire-prevention

https://web.archive.org/web/2012100...les/electrical/154_0710_jeep_fire_prevention/

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Basically - cut the wires behind the switch in the dash and have them activate/trigger the relays. Then run key-activated 12V (I think I pulled mine from the cigar lighter) to be the 12V that is the source that then goes to the blower motor.

This keeps the motor from drawing extra current through the switch as it wears out and peaks it's current draw on on the lowest setting (which melts the HVAC switch in the dash).

The blower motor resistor pack still remains a 'fuse' in the system — but that's cheaper than the HVAC switch panel...