Rear A/C Control

[Csides]

2005 Suburban 2500 8.1L. The rear A/C blower has stopped, no matter if I try to control it with the front console controls or the second row controls. I have checked the blower with independent 12v and it works. The wiring to the resistor has 12+volts and good ground. The resistor was replaced. The 30 amp fuse and the 10 amp ign 3 fuse are good. The purple wire that is for regulating voltage depending on fan speed and which routes to the resistor shows .1-.2 volts in the rear of the vehicle. Apparently this purple wire does not route to the second row controls, or at least I could not locate it.

I think I need to check continuity on this thin purple wire but I do not know where it comes from. I looked under the drive dash at the black control box but did not see a purple wire there. Obviously I do not have a wiring diagram. I suppose it connects to a different color wire somewhere in the harness?

Can anyone tell me the routing of this purple wire? Thank in advance for any help.

 

[Doubeleive]

2005 Suburban 2500 8.1L. The rear A/C blower has stopped, no matter if I try to control it with the front console controls or the second row controls. I have checked the blower with independent 12v and it works. The wiring to the resistor has 12+volts and good ground. The resistor was replaced. The 30 amp fuse and the 10 amp ign 3 fuse are good. The purple wire that is for regulating voltage depending on fan speed and which routes to the resistor shows .1-.2 volts in the rear of the vehicle. Apparently this purple wire does not route to the second row controls, or at least I could not locate it.

I think I need to check continuity on this thin purple wire but I do not know where it comes from. I looked under the drive dash at the black control box but did not see a purple wire there. Obviously I do not have a wiring diagram. I suppose it connects to a different color wire somewhere in the harness?

Can anyone tell me the routing of this purple wire? Thank in advance for any help.

If, everything else checks out then the culprit is usually the rear control module.

https://www.ebay.com/sch/i.html?_nkw=2005+surburban+rear+ac+control+module&_sacat=0&_from=R40&_trksid=p2334524.m570.l1313&LH_TitleDesc=0&_odkw=2005+surburbam+rear+ac+control+module&_osacat=0

 

[pronstar]

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[TJ Baker]

2005 Suburban 2500 8.1L. The rear A/C blower has stopped, no matter if I try to control it with the front console controls or the second row controls. I have checked the blower with independent 12v and it works. The wiring to the resistor has 12+volts and good ground. The resistor was replaced. The 30 amp fuse and the 10 amp ign 3 fuse are good. The purple wire that is for regulating voltage depending on fan speed and which routes to the resistor shows .1-.2 volts in the rear of the vehicle. Apparently this purple wire does not route to the second row controls, or at least I could not locate it.

I think I need to check continuity on this thin purple wire but I do not know where it comes from. I looked under the drive dash at the black control box but did not see a purple wire there. Obviously I do not have a wiring diagram. I suppose it connects to a different color wire somewhere in the harness?

Can anyone tell me the routing of this purple wire? Thank in advance for any help.

In other GM vehicle that I have the purple wire is the speed control signal from the HVAC module or the auxillary HVAC control module depending on which blower being addressed. The module provides a PWM GROUND signal, not a positive voltage.

 

[TJ Baker]

See diagram(s) 5 or 7 . Circuit #374.

Electrical Diagrams — 2005 Chevrolet Suburban 3/4 Ton 2WD V8-8.1L VIN G Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Suburban 3/4 Ton 2WD V8-8.1L VIN G.

charm.li

 

[Csides]

Thank you for your suggestions and links. Turns out this purple wire came out of a black box I think is called the rear auxiliary control module. The feed INTO this module from the front of the vehicle was dead. After several hours of testing, searching, drinking, many frustrating entanglements of my multi-tester probe wires and several temporarily lost tools (girlfriend claims is due to the the drinking, but I am not certain), and what feels like half of my interior disassembled, I traced this to an orange 12v wire in a 22-pin connector that is tucked away behind a kick panel to the left of the parking brake. The pins for this orange wire were burnt. See pic. Somehow this orange wire provides power to the rear auxiliary control module, but apparently is only done so through witchcraft because last night there did not seem to be a logical connection between this wire and the control module. Anyway, that problem is fixed. This evening I will attempt reassembly of the interior and finding the location of those tools. Thanks again for your comments and suggestions.