Blower motor?

K

KennyV

New Member
Joined
Sep 28, 2022
Messages
20
Location
Lancaster PA
I have 1997 tj 5sp 4.0
My fan and defroster will not work. ive looked at some of the parts and i would guess it is either the blower motor or the blower motor control module. any recomendations to figure that out without buying both parts?
 
There are a few things that you can check to determine whether it is the blower motor or the blower motor control module that is causing the issue in your Jeep TJ. Here are a few steps that you can follow:

1. Check the fuses and relays: First, check the fuses and relays related to the blower motor system in your Jeep TJ. There should be a fuse box under the hood and another in the passenger compartment. Look for any blown fuses or faulty relays related to the blower motor.

2. Check the wiring: Next, check the wiring leading to the blower motor control module and the blower motor itself. Make sure that there are no broken or damaged wires that could be causing a short circuit or preventing the motor from working.

3. Test the blower motor: If the fuses and wiring check out, you can test the blower motor by connecting it directly to a power source (e.g. your vehicle battery) using jumper wires. If the motor turns on and operates normally, then the problem is likely with the blower motor control module.

4. Test the blower motor control module: If the blower motor does not turn on, then the problem is likely with the blower motor itself. However, before replacing the motor, you can test the control module by using a multimeter to check for voltage at different points in the wiring. Consult your Jeep TJ's repair manual for detailed instructions on how to do this.

If you are not comfortable performing these tests yourself, you may want to take your Jeep to a mechanic or dealership for further diagnosis. They should be able to determine which part is causing the problem and recommend the appropriate repair.
 
KennyV said:
I have 1997 tj 5sp 4.0
My fan and defroster will not work. ive looked at some of the parts and i would guess it is either the blower motor or the blower motor control module. any recomendations to figure that out without buying both parts?
Click to expand...
Odds are good the windings inside the blower motor started shorting together from the shellac insulation on them breaking down causing the motor to start drawing excessive current. That took out the resistor pack, possibly some of the wiring insulation, and ultimately the blower motor itself. I'd plan on at least a new blower motor and resistor pack. No store brands allowed.
 
  • Like
Reactions: PNW_LJ
KennyV said:
I have 1997 tj 5sp 4.0
My fan and defroster will not work. ive looked at some of the parts and i would guess it is either the blower motor or the blower motor control module. any recomendations to figure that out without buying both parts?
Click to expand...

If you haven't already, download the service manual, it has wiring diagrams.

Work backwards. You can access the blower motor connector from the engine bay. See if you have power there. If not, you can determine if it's the 12v+ side or ground side that is causing the issue. Then chase that circuit.

12v+ is the simple side of the circuit. Just a relay that energizes it with key on.

Ground side is what goes thru the controls and fan speed resistor. It is significantly more complicated.

Search my posts on hvac. Lots of good info there.
 
BTW, if you have power at the blower motor and it's not spinning... then it's time to replace it

@Jerry Bransford recomendation is good. Just note that these Jeeps suffer from poor wiring issues as well.

Might want to open the dash to see if the switch panel is ok.
 
TrueTexas said:
BTW, if you have power at the blower motor and it's not spinning... then it's time to replace it

@Jerry Bransford recomendation is good. Just note that these Jeeps suffer from poor wiring issues as well.

Might want to open the dash to see if the switch panel is ok.
Click to expand...
Those wiring issues in the fan circuit are generally caused by the fan motor windings shorting together drawing excessive current that melts the wiring insulation.
 
Jerry Bransford said:
Wiring issues in the fan circuit are generally caused by the fan motor windings shorting together drawing excessive current that melts the wiring insulation.
Click to expand...

Agree this is a common failure point.

For me, it was excessive corrosion in the wiring that caused a large voltage drop in the last leg of the wiring to the blower. This reduced voltage increased the amp draw and that in turn created the excessive heat that melted connectors etc... making the problem even worse.

I initially installed a new blower motor (Mopar) and it was still pulling 24 amps. Once I replaced all the wiring, it pulls around 12 amps.

My other wiring changes routed the high current away from the controls in the console for further piece of mind
 
All the above is great info. For safety, when the blower motor resistor fails, it “defaults” to the the highest fan setting. Thats not what’s happened in your case. I’d start with confirming Power and ground at the motor as already suggested.
 
Jerry Bransford said:
Odds are good the windings inside the blower motor started shorting together from the shellac insulation on them breaking down causing the motor to start drawing excessive current. That took out the resistor pack, possibly some of the wiring insulation, and ultimately the blower motor itself. I'd plan on at least a new blower motor and resistor pack. No store brands allowed.
Click to expand...

as far as where the blower motor is and the best way to access it, is that just pulling the dash and looking for it?
 
You don't pull the dash. It is accessible from the engine bay behind the pcm.

You will need to disconnect and unbolt the pcm from the firewall
 
Top Bottom
Back