front climate control replacement?

Blacktrails

Member
Dec 8, 2011
34
No theres alot more to it then that. I don't know all the details but i know that it involves replacing the entire HVAC system. Sensors, controls, vacuum hoses. It can be done but its not very practical.

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Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
No vacuum hoses, but yeah it's too expensive and time consuming to be worthwhile. I know of 1 guy who did it on the OS, that's about it.

You can find cheap used ones for replacements on Ebay, just make sure there's a picture of the unit. I had to replace mine (due to a botched LED mod) and the ad I found didn't have a pic on it, just the description and RPO code. The one they sent me did NOT have the rear defrost button on it :confused: so I had to send it back and get another one. :duh:
 

itstrick

Member
Dec 10, 2011
29
There must be a lot more to the manual ones compared to the digital ones? my digital was just a plug in back of it.
 

Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
itstrick said:
There must be a lot more to the manual ones compared to the digital ones? my digital was just a plug in back of it.

You got it backwards. It's not just the digital/manual module, but the digital one has an ambient air temp sensor in the driver's side B pillar, manuals don't. There's all the wiring associated with that sensor, also the exterior ambient air temp sensor behind the front grille (some models that do not have the outside air temp in the rear view mirror would have to add this as well)
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Blckshdw said:
...the digital one has an ambient air temp sensor in the driver's side B pillar...
Plus 5 additional temp sensors in the ductwork for closed loop feedback that the manual system doesn't have, plus a left/right sunload sensor in the little dome at the front center of the dash so it knows which side of the car the sun is shining on, plus the blower speed control module is the more expensive continuously variable one instead of the 5-speed discrete resistor pack. That's what makes the wiring harness upgrade so painful. Without a donor vehicle and access to factory schematics, it's an expensive or impossible mod.
 

91RS

Member
Dec 4, 2011
105
the roadie said:
Plus 5 additional temp sensors in the ductwork for closed loop feedback that the manual system doesn't have, plus a left/right sunload sensor in the little dome at the front center of the dash so it knows which side of the car the sun is shining on, plus the blower speed control module is the more expensive continuously variable one instead of the 5-speed discrete resistor pack. That's what makes the wiring harness upgrade so painful. Without a donor vehicle and access to factory schematics, it's an expensive or impossible mod.

I will be making the attempt in the near future. Does anyone know the member's name from the OS that did the conversion? Did he post up any information on how he did it?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
91RS said:
Did he post up any information on how he did it?
I forget the name, but it was an Envoy. Sorry, not going to search the OS. He said it took access to the factory manuals and schematics, and was not worth the effort except as a technical challenge that nobody had ever attempted. The cost/benefit ratio is pretty small. I have the shop manual and schematics, and predict you'd have to spend $300 on parts alone, even using Ebay for the speed control module and the head unit. You'd need a lot of Delphi connectors to make your own harness. And disassembling the dash is not for the faint of heart. Without compnine available for exploded parts views, you'd also need that sort of resource, or a donor vehicle to look at as you disassemble it in the junkyard.

dash05.jpg
 

itstrick

Member
Dec 10, 2011
29
Blckshdw said:
You got it backwards. It's not just the digital/manual module, but the digital one has an ambient air temp sensor in the driver's side B pillar, manuals don't. There's all the wiring associated with that sensor, also the exterior ambient air temp sensor behind the front grille (some models that do not have the outside air temp in the rear view mirror would have to add this as well)

Sorry, I think I ment there is more to R&I on the manual vs digital
 

DMD_TB

Original poster
Member
Dec 4, 2011
75
Blckshdw said:
No vacuum hoses, but yeah it's too expensive and time consuming to be worthwhile. I know of 1 guy who did it on the OS, that's about it.

You can find cheap used ones for replacements on Ebay, just make sure there's a picture of the unit. I had to replace mine (due to a botched LED mod) and the ad I found didn't have a pic on it, just the description and RPO code. The one they sent me did NOT have the rear defrost button on it :confused: so I had to send it back and get another one. :duh:

Ok thanks a ton guys definitely not worth it
 

91RS

Member
Dec 4, 2011
105
the roadie said:
I forget the name, but it was an Envoy. Sorry, not going to search the OS. He said it took access to the factory manuals and schematics, and was not worth the effort except as a technical challenge that nobody had ever attempted. The cost/benefit ratio is pretty small. I have the shop manual and schematics, and predict you'd have to spend $300 on parts alone, even using Ebay for the speed control module and the head unit. You'd need a lot of Delphi connectors to make your own harness. And disassembling the dash is not for the faint of heart. Without compnine available for exploded parts views, you'd also need that sort of resource, or a donor vehicle to look at as you disassemble it in the junkyard.

dash05.jpg

I'm not worried about that. I've access to all those things. I've also taken a few instrument panels out, I even took the carrier out on one to fix a rattle from the heater core. I'm also adding steering wheel controls so I may do both at the same time. It looks like I need to rewire the the recirc door actuator so I might as well replace the ducts with the sensors rather than drilling holes since the dash has to come off anyway. I can't stand the manual A/C, I had auto A/C in my 02 (as well as the steering wheel controls) so it's worth it to me.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
IIRC, only the '02 offered HVAC controls in the steering wheel. Might have to research that a bit. No idea why they stopped the option. Maybe the folks who had the automatic HVAC were also getting the DIC and you can't have DIC, HVAC, *and* audio controls all on one steering wheel?
 

91RS

Member
Dec 4, 2011
105
the roadie said:
IIRC, only the '02 offered HVAC controls in the steering wheel. Might have to research that a bit. No idea why they stopped the option. Maybe the folks who had the automatic HVAC were also getting the DIC and you can't have DIC, HVAC, *and* audio controls all on one steering wheel?

2002-2003 had the HVAC controls in the steering wheel. Another thing I'll miss about my 02. I may look into adding that too since that button goes to the BCM and the BCM sends a Class 2 message to the HVAC module, so unless the programming is gone for that button I may be able to add that. I don't care about the Onstar buttons.
 

Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
91RS said:
2002-2003 had the HVAC controls in the steering wheel. Another thing I'll miss about my 02. I may look into adding that too since that button goes to the BCM and the BCM sends a Class 2 message to the HVAC module, so unless the programming is gone for that button I may be able to add that. I don't care about the Onstar buttons.

:confused: They had OnStar buttons in the steering wheel too back then?
 

91RS

Member
Dec 4, 2011
105
Blckshdw said:
:confused: They had OnStar buttons in the steering wheel too back then?

No, the Onstar buttons replaced the HVAC buttons. The upper left button controlled fan speed and temperature on the 02-03 wheel, but after that it changed to Onstar.
 

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