VengefulIcebox

Hello fellas,

I hate to start another thread on blower motors, but I'm at a stopping point on my end. I'd rather fix it right than wire in a override switch bypassing the OEM climate controls. So I'm here to ask for help.
I've googled, watched vids, and voltmetered some points, here's what I have done and got so far.

1997 XJ, bare bones model - no power windows, no power locks, no auto climate control, etc. 4.0 liter. Auto trans. 4WD.

-Blower motor not operating on any switch speed.
-Fuse removed, checked good, re-installed.
-No voltage to blower motor.
-Replaced resistor with new.
-Replaced relay with new.
-Disconnected wire loom connector from back of blower speed switch, 5 wires present, 3 fat wires, 2 thin. The thin green wire reads 12v when tested together with the (I believe) dark brown with a blue stripe-the first fat wire on the end, left. The thin green and orange wire also read 12v when metered together.
-Removed climate control panel, disassembled fan control switch, appears to be a simple rugged unit, copper circuit bars do not have corrosion, selector spring appears to apply tension from 3 selector **** power distributor nodes to copper circuit bars while indexing selector **** along detents. Reassembled.
-Checked blower motor plug again, still no volt reading.
ETA
-Relay has voltage at switch leads, but no voltage for the motor throughput. In other words the relay switch is getting power to operate, but there is no blower motor power getting up to the relay to be passed on.
-No voltage at the resistor with the fan speed selector switch set at any speed.

Fuse good, new relay and resistor, fan switch looks good. It's got to be something simple. I've looked up the wiring diagram, I couldn't pick out anything outstanding to follow up on.


Thanks for any help!

Turbo X_J

"fan switch looks good."

Switch & connector are common faults.

VengefulIcebox

I'll go back and check for any voltage output from fan speed switch.
All the connectors have been wiggled well.

Thanks Turbo XJ

CCKen

Which "Fuse"? There's two fuses involved. Fuse F6, 40 Amp, in the PDC and Fuse F25, 15 Amp, in the JB.

Fuse F6 in the PDC is the main power fuse to the blower, through the relay contacts. Fuse F25 in the JB is power to the relay control coil (RUN A22 Circuit).

VengefulIcebox

Hello CCKen.

In my owners manual, PDC 30 is a 40 Amp fuse, which was what I referenced in my previous post checking out good. Under hood, 3rd in row closest fender.

I checked the mini fuses, including the 15 amp in position 25 of the passenger compartment floorboard fuse box.

Double checked both after your post. Both appear fine.

CCKen

Here's a diagram of the 97 PDC.

I take it when said fuse 30, you meant fuse 3. Fuse 3 is for the ignition switch and fuse 6 is for the HVAC Blower.

Are we on the same track?



Here's a JB guide that someone put together.

CCKen

i can't make heads or tails out of the 97 HVAC blower circuit. There's something missing, like a ground for the mode selector and fan switches.



Here's the HVAC blower circuit for the later XJ's. Note the ground circuit for the Mode and Fan select switches, and the lights. This circuit is very similar to the 97 circuit diagram. See if you can use this diagram.

VengefulIcebox

Hello CCKen,

I think the owners manual diagram and the service manual/internet diagram are orientated differently. Which is causing a comm barrier. My fault, I should have stuck with the forum's standard - the one used by others here and referenced in your recent post.

Fuse 6 is what I have checked for the PDC.
In the JB (junction box?) the reference photo doesn't have numbers coinciding with the list, but 1-30 starting upper left reading down and resuming on the next row top would line up as #25 the blue 15 amp.

I checked each and every fuse in both the PDC and JB out of curiosity. Also the PDC was voltmetered to insure there was power going into the #6 slot, to rule out a wire loom break.

I'm not sure what else to do to keep it pro. May have to put in a bypass switch after all.

Thanks for the effort CCKen.

VengefulIcebox

Looking at the last diagram, of the HVAC BLOWER CIRCUIT, it looks like the power flow is Batt>PDC 40 amp fuse>Dash switch>Resistor>Blower Motor>Relay. With Relay just completing the circuit at the end to put things in motion.

No power at relay, farther up stream is the motor, no power there. I made a mistake at the resistor plug when testing, can retest tomorrow. Also the switch can be retested as I overlooked something there too.

A111,C7,C6,C5,C4 appear to be the 5 wires in the plug connecting near the switch on the back of the control pod. I put the dash back together and am not looking at it now, going off memory.
A111 and C5 read 12V. C5 and C4 read 12V. No other combination seemed to produce any reading. Need to recheck it tomorrow and place the selector switch in different positions while testing.

I only metered the resistor plug terminals themselves. After looking at the diagram I need to introduce a ground to the test circuit, there's no ground apparent in the plug itself. It looks like the C7-12-BK/TN can be jumped to skip the resistor and supply high speed only.

I'll look at it again in the morning. If I can come up with power at the resistor but not the motor plug, may be it's just a bad brand new resistor? New parts are sometimes bad. Or a faulty connection at the resistor, as TurboXJ reminded of earlier.

CCKen

It may not apply in your case, but the resistor block has a thermal fuse in it. If the blower locks up the thermal fuse will blow. The thermal fuse is not shown in these wiring diagrams. I did see it in a 94 diagram, I think.

If you physically look at a resistor block you can see it. Most pics of a resistor block on the net will not show it. Thinking my resistor block couldn't possibly have this fuse because it's not on the diagrams I went to a NAPA store and asked them to see a resistor block for a 1999 XJ, Bigger than $h!t, there it was.

justin13703

I had this problem with my 97, I found a wire running from the fuse box with a fuse in it, through the firewall. It was installed by the po and I didn't know what it was for so I pulled the fuse to be safe. Then my blower stopped working.

Turns out there was a problem with the circuit somewhere on the wire that runs to the relay behind the glove box that is supposed to get power with the ignition. So that wire I found was providing the ignition power to the blower motor relay. I put the fuse back in and it worked. Probe your blower relay and make sure it is getting constant 12v, ignition 12v, and a good ground. Mine wasn't getting the ignition 12v through the factory wire and that's why the new one was run apparently.

According to the above diagram the wire that I had the problem with was the dark blue/white one that runs from the junction block to the blower motor relay