QuestionQUESTION: Wife just got a 2004 gmc envoy, but the rear hvac controls won't work. (rear air does work with front controls) I checked the fuse under the back seat, but it tested good. Any Thoughts?
ANSWER: Hi
Does the Rear HVAC control module light up?
Does the blower work?
Or is the air delivery faulty?
From the front you should just be able to control fan speed, correct?
Willing to help, please follow post back
Pawl
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QUESTION: The rear HVAC controls do light up and the blower does work. The fan does blow properly from the front control, but does not blow at all when the fron control is on rear control, no matter what speed the rear control is on.
ANSWER: One last set of questions
Could you give me the 7th (seventh) digit on your VIN
Will be either a 3 or a 6.
Also do you have an XUV? (The roof opens, has a midgate ond 2 way rear liftgate)?
Sorry for the questions, but the diagnostics worksheets differ between the 3 different options.
Thanks and sorry
Pawl
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QUESTION: No problem, I greatly appreciate your help. It is not an XUV and the 7th digit is "6". Thanks!
AnswerHi Jeff.
There is a VERY long diagnostic workesheet for the vin 6 rear blower inop from rear switch. I will GLADLY send it to you but the first step is a scan tool parameter that needs to be observed, and there is some fairly time consuming electrical tests that need to be checked. I can tell you that the ONLY parts that can be at fault, according to worksheet is either the FRONT switch, the REAR switch or the blower motor itself? (I cannot figure why). The data you need to check is to make sure when you put the front switch in the rear position, that is actually switching into that switch position. This can be observed on a scan tool.
If it IS switching, you can almost be assured that the rear switch is at fault.(located in the back of center console).
So without answering your question AGAIN, (I really want to help you get this fixed) please let me know what you would like... the worksheet? IF you could get that data checked (Turn ON the ignition, with the engine OFF.
With a scan tool, observe the Driver Override Switch parameter in the REAR HVAC/RSA data list.
Place the front auxiliary blower motor switch in each position.
Does the scan tool indicate that the Driver Override Switch parameter changes state?) then this data (Important: Ensure that the front auxiliary blower control switch is in the REAR position during the remainder of this table in order to avoid misdiagnosis.
Turn ON the ignition, with the engine OFF.
Place the front auxiliary blower motor switch in the REAR position.
With a scan tool, observe the Rear HVAC Fan Up Switch parameter in the REAR HVAC/RSA data list.
Activate the auxiliary fan up switch.
Does the scan tool indicate that the Rear Fan Up Button parameter changes state?) then your rear switch is bad, FOR SURE.
Find this out and if any other questions arise, please do a private post so I can shoot you some emails with the worksheet.
I am sorry and I DO hope this helps.
Good luck
Pawl
