# 1997 Jeep Grand Cherokee Ltd. Automatic Climate Control, no power to panel



## GZ (Jan 31, 2010)

Okay... Here is one that I can't find any info on... I keep running across diagrams for the Manual Control but not the automatic.

The vehicle..

1997 Jeep Grand Cherokee V8 LTD.

The issue...

The Automatic Climate Control panel does not function. (no lights, no function, nothing).

What I have done.


Checked the fuse panel for blown fuses (Passenger kick panel and Distribution box)
Inspected harness under dashboard for damaged, spliced and modified wiring.
Disassembled the CCU and inspected for internal damage/fault.
Performed a multi-meter (voltage) test of each lead going into the CCU with the ignition switch on. Unfortunately, I was using an ancient POS multi-meter... Next time I have the vehicle, I will use my own meter... The largest voltage reading I got was just over 6V... I didn't take notes as to which lead gave which voltage... Sorry...

Secondary issue, probably unrelated... The stereo only outputs to the dashboard and the sound is high and tinny (tweeters???). No sound appears to be coming from the door-panel speakers.

The under dash wiring is intact and does not seem to be modified in any way. The factory cloth tape is still holding the wire loom together. 

All fuses appear to check out... First ones checked were HVAC fuses.. Both were good... Pulled most of the fuses from the box and visually inspected them.

The internals of the CCU seem to be in good shape. All ICs are intact, all 3 capacitors seem fine. I could not find any sign of cold-joints or fatigue.

Voltage readings were inconclusive... No 12V readings on any input.

I do not have possession of this vehicle. I am helping it's owner try and figure this issue out. Any and all suggestions and possibilities welcome. The next time I will have possession of this vehicle is tomorrow afternoon.

Thanks in advance..


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## octaneman (May 13, 2009)

Here are the diagrams for the climate control unit.

Using your DMM probe the pin voltages by turning the swithes on/off. There will be a slight drop in voltage readings when the load is on (this is normal) but if its excessive disconnect the connectors one-by-one to isolate the draw.


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## GZ (Jan 31, 2010)

Thank you! Will get back to you later on.


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## Troy_Jollimore (Dec 31, 2007)

The stereo could be hooked up a couple of ways. You could be right with them being separate tweeters and woofers (it IS the GRAND Cherokee, after all). If that's the case, the wiring probably goes between each side and then has a small capacitor or board that reroutes the signal to each speaker. Simple continuity checks should be enough to get you through checking those.


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## GZ (Jan 31, 2010)

Thank you Troy. Luckily I know enough about car audio... I am not worried about the stereo at all... I only mentioned it in case it could be related to the Climate control system... These OEMs have funny ways of wiring things that make no sense half the time... In some cars the BCM controls the stereo system as well as HVAC and such...


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## GZ (Jan 31, 2010)

Haven't had a chance to look at the wiring yet... Spent too much time on the trans-service the other day...

Quick question on a side note...

Did the trans service... Fluid was discolored and the filter was clogged a bit... Pan had aluminum and brass flakes in it banghead... Full trans flush and 11qt of fresh ATF+4 added... Now, I am pretty sure the Torque converter is ready to fail completely... The symptoms are all occasional... Perhaps 2% of the time driving... 

Rarely, especially when cold, the trans loses it's coupling to the motor... This is indicated by free-revs up to 3500RPM before the torque converter slams into lock...

I have eliminated slipping clutches as a suspect due to the fact that 98% of the time the trans works beautifully... 

Now, my question... Would it be best just to replace the Torque Converter with a known good one? Other than the occasional issue, the trans shifts and works beautifully...


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## Basementgeek (Feb 7, 2005)

If can get a lnown good used one, worth a shot. With that much crud in the pan, I would guess the transmission is not long for this world.

BG


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