heater problems in my 00 5.3

dougs01gt · November 9, 2004

If i turn the temp dial to hot i get heat fine but when i turn it to cold it stays pretty hot still. Im sure its related to the door for the heater core but im not sure. Also if i shut the truck off for alittle while with the dial on cool its stays cool but if i turn it up it stays on again. any thoughts??

Thanks in advance

mcreyaufmiller · November 9, 2004

I am not sure, does your truck have a heater control valve that directs the coolant? I have had problems in the past with one of these not working correctly.

Mike

SalvageZR2 · November 26, 2004

I have the same problem in my 03 1500HD, but only on the passenger side heater control. If I turn it all the way to hot it works as it should, however when I try to back it off it continues blowing max heat air until the truck is shut off and restarted. I have seen a few other threads about this problem but couldn't find where anyone found a solution. Anyone? I'd like to get it fixed before the warranty runs out!

Thanks.

budhayes3 · November 26, 2004

Sounds like a blend door or door motor problem to me. Here's a couple of TSB's that might help:

A/C - Loss of Mode/Temperature Control

File In Section: 01 - HVAC

Bulletin No.: 01-01-39-007

Date: January, 2002

TECHNICAL

Subject:

Loss Of HVAC System Mode and/or Temperature Control

(Reroute Wiring Harness)

Models:

1999-2002 Chevrolet and GMC C/K Pickup Models (Silverado and Sierra) 1999-2002 Chevrolet and GMC C/K Utility Models (Avalanche, Suburban, Tahoe, Yukon, Yukon XL, Denali) 2001 GMC Sierra C3

2002 GMC Sierra Denali

2002 Cadillac Escalade, Escalade EXT

Condition

Some customers may comment that they cannot control the HVAC system modes and/or the temperature. These concerns may be intermittent.

Cause

There may be poor terminal contact and/or bent terminals in connectors C206 (RPO C68 automatic HVAC controls) or C296 (RPO C60 manual HVAC controls). Excessive tension on the wires due to the wiring harness being misrouted in the instrument panel carrier may cause these conditions.

Correction

1. Remove the Air Bag fuse.

2. Disconnect the steering wheel and instrument panel (IP) air bag connectors. Refer to the SIR subsection of the Restraints section of the Service Manual for connector locations.

3. Remove the IP upper trim pad.

4. Locate connector C206 (6 cavities) or C296 (8 cavities). The connector is attached to a metal brace on the far right side of the IP carrier above the IP air distributor duct.

5. Inspect the routing of the wiring harness to the connector. The proper routing of the wiring harness is above the air distributor duct with no tension on the terminals in the connector. The routing is improper if the wiring harness is below the air distributor duct with excessive tension on the terminals in the connector. The excessive tension may cause poor terminal contact, resulting in open circuits, in the connector. The wires may also pull the terminals out of the connector or pull out of the terminal itself.

6. If the harness is routed properly, contact Technical Assistance for further information.

7. If the harness is misrouted, remove the connector from the brace.

8. Disconnect the connector.

9. Perform a pin drag test on the female terminals.

10. Inspect the male terminals for straightness.

11. Inspect the wire to terminal connection to insure that no wires have pulled out of the terminals.

12. Reroute the wiring harness above the air distributor duct.

13. Firmly reconnect and reseat the connector.

14. Reattach the connector to the metal brace.

15. Reinstall the IP upper trim pad.

16. Turn Off the ignition and reconnect the steering wheel and IP air bags.

17. Reinstall the Air Bag fuse.

18. Turn ON the ignition and verify that the air bag light flashes seven times and goes out.

19. Clear any diagnostic trouble codes that may have been set.

20. Verify proper operation of the HVAC system mode and temperature controls

____________________________________________________________________

A/C - Loss of Mode or Temperature Control

Bulletin No.: 04-01-39-007

Date: June 17, 2004

TECHNICAL

Subject:

Loss Of HVAC System Mode and/or Temperature Control (Replace HVAC Control Module)

Models:

2002 Cadillac Escalade, Escalade EXT

1999-2002 Chevrolet Silverado, Suburban, Tahoe

2002 Chevrolet Avalanche

1999-2002 GMC Denali, Sierra, Yukon, Yukon XL

2001 GMC Sierra C3

2002 GMC Sierra Denali

with Automatic HVAC System (RPO C68)

Condition

Some customers may comment that they cannot control the HVAC system modes and/or the temperature. These concerns may be intermittent.

Cause

An HVAC control module logic lock-up may be the cause of these conditions.

Correction

Important: Prior to replacing the HVAC control head, review Corporate Bulletin Number 01-01-39-007.

Replace the HVAC control module. Refer to the HVAC Control Module Replacement procedure in the HVAC System - Automatic sub-section of the Service Manual.

Good luck, hope this helps!

-Billy