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Posted: 11/21/2012 4:25:08 PM EST
[Last Edit: 11/22/2012 4:21:43 PM EST by andrasik]
So my Jeep was good to go when I bought it. HVAC worked fine. Then position number 3 died. Then all of them died.

I have:
*Checked HVAC fuse under the hood, it's good.
*Checked AC fuse behind glove box, it's good.
*Replaced blower motor resistor.
*Replaced fan switch.

I still can't get it to blow at all. When driving, I notice that I can feel heated air coming through the vents. If I turn the knob to cool, it blows a little cooler air, but nowhere near even the amount that position 1 would blow.

I'm out of ideas now. What am I missing?

UPDATE -
I replaced the fan switch and still no-go. Blower motor next?
Link Posted: 11/21/2012 4:29:13 PM EST
[Last Edit: 11/21/2012 4:31:58 PM EST by bloodsport2885]
Originally Posted By andrasik:
So my Jeep was good to go when I bought it. HVAC worked fine. Then position number 3 died. Then all of them died.

I have:
*Checked HVAC fuse under the hood, it's good.
*Checked AC fuse behind glove box, it's good.
*Replaced blower motor resistor.

I still can't get it to blow at all. When driving, I notice that I can feel heated air coming through the vents. If I turn the knob to cool, it blows a little cooler air, but nowhere near even the amount that position 1 would blow.

I'm out of ideas now. What am I missing?


Fan switch in the dash. When you have progressive failure of speeds its either the resistor or the switch. While you've got it apart check all control cables/solenoids for your climate control doors.

ETA the small amount of heat your feel is probably blow-by due to pressure changes between inside and outside the cabin.
Link Posted: 11/21/2012 4:35:33 PM EST
Originally Posted By andrasik:
So my Jeep was good to go when I bought it. HVAC worked fine. Then position number 3 died. Then all of them died.

I have:
*Checked HVAC fuse under the hood, it's good.
*Checked AC fuse behind glove box, it's good.
*Replaced blower motor resistor.

I still can't get it to blow at all. When driving, I notice that I can feel heated air coming through the vents. If I turn the knob to cool, it blows a little cooler air, but nowhere near even the amount that position 1 would blow.

I'm out of ideas now. What am I missing?


How about sharing the year and model? That makes a pretty big difference...

Link Posted: 11/21/2012 4:45:16 PM EST
Originally Posted By bloodsport2885:

Fan switch in the dash. When you have progressive failure of speeds its either the resistor or the switch. While you've got it apart check all control cables/solenoids for your climate control doors.

ETA the small amount of heat your feel is probably blow-by due to pressure changes between inside and outside the cabin.


Agreed. On some vehicles the current drawn by the fan passes through the switch. With this design you'll eventually have the switch burn out. It's a pretty bad design. Interesting that three went out and then all at once.
Link Posted: 11/21/2012 4:50:49 PM EST
Wire blower motor direct to +12VDC and verify operation. I repolace the blower on my '97 cherokee about every 24 months. I doni't know your make and model. After that I would pull the resistor pack out and check input and output votlage on each coil, then go back to switch.

I am assuming you already checked the fuses and made sure you didn't loose a coil in the resistor (lost 3) and it bounced and shorted and lost the others.


Dan
Link Posted: 11/21/2012 4:55:07 PM EST
Take a multi-meter to the Switch. Measure ohm's in all positions of dial.. Probably just that.
Link Posted: 11/21/2012 6:22:56 PM EST
Originally Posted By Dan12:
Wire blower motor direct to +12VDC and verify operation. I repolace the blower on my '97 cherokee about every 24 months. I doni't know your make and model. After that I would pull the resistor pack out and check input and output votlage on each coil, then go back to switch.

I am assuming you already checked the fuses and made sure you didn't loose a coil in the resistor (lost 3) and it bounced and shorted and lost the others.


Dan


Wait, you replace blower motors every 2 years? Dude, I will cut you one hell of a deal on transmissions. How often do you replace those?
Link Posted: 11/21/2012 6:28:38 PM EST
[Last Edit: 11/21/2012 6:28:56 PM EST by robplumm]
Does anything happen when you turn the knobs?

On the TJ at least (and assume all 4.0), the different settings were controlled by pressure off the engine and there's a vacuum line that runs to the engine for this. It had a tendency to come undone. It's on the driver's side.
Link Posted: 11/21/2012 6:28:44 PM EST
It's the switch. Jeeps from about '95 to '06 are notorious for this. Mine is an '04 and has gone through 3 of them.
Link Posted: 11/21/2012 6:29:55 PM EST
[Last Edit: 11/21/2012 6:31:53 PM EST by mmf]
It's most likely the resistor assembly, mounted in the plenum on the passenger side behind the glove box. 2 types are common depending on year, 1 with several coils on a board or an electronic version that is a small black rectangle with the connector at one end.

Both mount in same location.
Link Posted: 11/21/2012 6:30:43 PM EST
Originally Posted By xXNuggettXx:
Originally Posted By bloodsport2885:

Fan switch in the dash. When you have progressive failure of speeds its either the resistor or the switch. While you've got it apart check all control cables/solenoids for your climate control doors.

ETA the small amount of heat your feel is probably blow-by due to pressure changes between inside and outside the cabin.


Agreed. On some vehicles the current drawn by the fan passes through the switch. With this design you'll eventually have the switch burn out. It's a pretty bad design. Interesting that three went out and then all at once.


Yup, BTDT.
Link Posted: 11/21/2012 6:33:25 PM EST
Blower motor resistor.
Just wait till it really takes a dump and you walk away from your Jeep with the keys in your hand and your blower motor starts funning full speed until it totally drains the battery.

Link Posted: 11/21/2012 6:35:39 PM EST
Originally Posted By mmf:
It's most likely the resistor assembly, mounted in the plenum on the passenger side behind the glove box. 2 types are common depending on year, 1 with several coils on a board or an electronic version that is a small black rectangle with the connector at one end.

Both mount in same location.


Reading is tough.
Link Posted: 11/21/2012 6:47:36 PM EST
Thanks for the tips guys, the switch makes sense.

It's a '99 Wrangler Sport 4.0 BTW.
Link Posted: 11/21/2012 10:02:09 PM EST
Originally Posted By andrasik:
Thanks for the tips guys, the switch makes sense.

It's a '99 Wrangler Sport 4.0 BTW.


I have the same Jeep and the third position is out on mine also. The rest are still working fine.
Link Posted: 11/22/2012 4:21:26 PM EST
Update in OP.
Link Posted: 11/22/2012 4:23:31 PM EST
[Last Edit: 11/22/2012 4:24:07 PM EST by johnnypantz]
Did you check all the fuses?

Not just the ones you think are relevant

Link Posted: 11/22/2012 4:24:23 PM EST
Originally Posted By johnnypantz:
Did you check all the fuses?

Not just the ones you think are relevant



Yep
Link Posted: 11/22/2012 4:26:24 PM EST
Originally Posted By andrasik:
So my Jeep was good to go when I bought it. HVAC worked fine. Then position number 3 died. Then all of them died.

I have:
*Checked HVAC fuse under the hood, it's good.
*Checked AC fuse behind glove box, it's good.
*Replaced blower motor resistor.
*Replaced fan switch.

I still can't get it to blow at all. When driving, I notice that I can feel heated air coming through the vents. If I turn the knob to cool, it blows a little cooler air, but nowhere near even the amount that position 1 would blow.

I'm out of ideas now. What am I missing?

UPDATE -
I replaced the fan switch and still no-go. Blower motor next?


Do you have a FSM?

Link Posted: 11/22/2012 4:31:18 PM EST
00 TJ here, the resistor and the switch go bad.

As the blower motor gets older it builds resistance, they used to small of a guage of wire. The switch connector can melt (mine has) and it causes the rresistor and switch to fail premature.

i have replaced this shit three times already.

It's a very common TJ problem

You may have to replace the motor resistor and switch.
Link Posted: 11/22/2012 4:31:43 PM EST
Originally Posted By ASUsax:
Originally Posted By andrasik:
So my Jeep was good to go when I bought it. HVAC worked fine. Then position number 3 died. Then all of them died.

I have:
*Checked HVAC fuse under the hood, it's good.
*Checked AC fuse behind glove box, it's good.
*Replaced blower motor resistor.
*Replaced fan switch.

I still can't get it to blow at all. When driving, I notice that I can feel heated air coming through the vents. If I turn the knob to cool, it blows a little cooler air, but nowhere near even the amount that position 1 would blow.

I'm out of ideas now. What am I missing?

UPDATE -
I replaced the fan switch and still no-go. Blower motor next?


Do you have a FSM?



FSM?
Link Posted: 11/22/2012 4:32:20 PM EST
I could actually hit the blower motor box with my folding four way wrench and the motor would start blowing.
Link Posted: 11/22/2012 4:33:53 PM EST
Originally Posted By andrasik:
Originally Posted By ASUsax:
Originally Posted By andrasik:
So my Jeep was good to go when I bought it. HVAC worked fine. Then position number 3 died. Then all of them died.

I have:
*Checked HVAC fuse under the hood, it's good.
*Checked AC fuse behind glove box, it's good.
*Replaced blower motor resistor.
*Replaced fan switch.

I still can't get it to blow at all. When driving, I notice that I can feel heated air coming through the vents. If I turn the knob to cool, it blows a little cooler air, but nowhere near even the amount that position 1 would blow.

I'm out of ideas now. What am I missing?

UPDATE -
I replaced the fan switch and still no-go. Blower motor next?


Do you have a FSM?



FSM?


Factory Service Manual. Worth getting one for any vehicle you own - much better than the Haynes/Chilton books, these are the actual books that the dealership uses.
Link Posted: 11/22/2012 4:37:57 PM EST
Link Posted: 11/22/2012 4:42:09 PM EST
blower motor resistor. Replace it...
Link Posted: 11/22/2012 5:07:41 PM EST
Again, take two pieces of wire. Unplug plug pigtail on blower motor. Apply 12bdc and verify proper operation if fan or use volt meter to verify voltage to blowe from have controls
Link Posted: 11/22/2012 5:12:18 PM EST
Originally Posted By Dan12:
Again, take two pieces of wire. Unplug plug pigtail on blower motor. Apply 12bdc and verify proper operation if fan or use volt meter to verify voltage to blowe from have controls


If it doesn't have a mouse or a turntable, andrasik can't use it
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