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Discussion Starter · #1 ·
The vents on my 2000 GC Limited with the 4.7l are blowing warm air constantly. I can't change the temperature with the control knobs; turning them has no effect.

Using the AZC self-diagnostic mode by pressing the a/c and recirc buttons at the same time and rotating the left temperature control knob clockwise one detent, I get the following error codes:
43 = Engine air intake temperature bus message missing
58 = Engine coolant temp bus message missing
59 = Vehicle speed bus message missing
60 = Engine RPM bus message missing
63 = VIN number bus message missing

Any suggestions for a fix will be appreciated.
 

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scan for codes - I suspect some codes you will need a scanner.
Check the PCI bus HVAC module to diagnostic port.
 

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Discussion Starter · #3 ·
scan for codes - I suspect some codes you will need a scanner.
Check the PCI bus HVAC module to diagnostic port.
Thanks jtec. I just took the Jeep to an auto parts store, and they scanned the OBD port. No errors were found.

I'm not sure how to check the PCI bus HVAC module to diagnostic port, but I'll Google it and then give it a try.

Sent from my SM-G998U using Tapatalk
 

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Try disconnecting the battery. Wipe the slate clean and see what pops up again. The AZC modules are a dime a dozen from parts yards too.

Can you hear the servos while you change the temperature?

I think when the blend doors fail the default is cold. Plus you’re not getting blend door codes.

Also check the wiring loom behind the blower motor that powers the servos. Try reseating it.

I get those codes on occasion but it doesn’t affect my HVAC
 

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Discussion Starter · #5 ·
Thanks sdg3205.

The HVAC seems to miraculously fixed itself, and is functioning now functioning correctly.

However, the codes are still there. I'll see what disconnecting the battery for a bit does, and will attempt to check the wires behind the blower motor.

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Before spending time checking circuits try sdg3205's suggestion dump the stored settings.

just disconnect battery.

doing BUS can be frustrating,
 

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Discussion Starter · #7 ·
Thanks again jtec and sdg3025. I'll do the battery disconnect today.

To be sure I'm doing it right, I disconnect the positive terminal, touch it to the a/c compressor mount (to ground it), then wait 15 minutes, and then reconnect the positive terminal back to the battery?

Please let me know if I have this procedure correct.

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Thanks again jtec and sdg3025. I'll do the battery disconnect today.

To be sure I'm doing it right, I disconnect the positive terminal, touch it to the a/c compressor mount (to ground it), then wait 15 minutes, and then reconnect the positive terminal back to the battery?

Please let me know if I have this procedure correct.

Sent from my SM-G998U using Tapatalk
I've read to disconnect the negative, let sit for 5-10 minutes.
Before reconnecting, turn on the lights. This will drain power from various capacitors.

Hope yours starts working, mine needs the doors replaced again.
 

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Discussion Starter · #9 ·
Did the battery disconnect, and all codes are gone! Thanks all for your help.

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