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Billy
Billy, Chevrolet tecnician
Category: Chevy
Satisfied Customers: 510
Experience:  Over 25 years experience,GM grand master for 8 years,certified smog and government safety inspector
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I HAVE A 2003 TAHOE W/ REAR HEAT AND AIR.. I NOTICED THE TEMP

Resolved Question:

I HAVE A 2003 TAHOE W/ REAR HEAT AND AIR.. I NOTICED THE TEMP CONTROL WOULD NOT CHANGE THE TEMP. TOOK THE ACCESS PANEL OF TO LOOK AT THE TEMP SWITCH AND THE ROOF , FLOOR CONTROL SWITCH TEMP SWITCH WAS NOT MOVING WHILE CHANGING TEMP
Submitted: 5 years ago.
Category: Chevy
Expert:  Billy replied 5 years ago.
Hello rob 1093 and welcome to just answer.

which temp. switch didn't change, front rear left right?
Is it the mode or the temperature that is not changing?

Best regards
Billy
Customer: replied 5 years ago.
IT WAS THE TEMP SWITCH THAT WOULDNT CHANGE.. SO I TOOK THE MODE SWITCH OUT AND PUT IT IN PLACE OF THE TEMP SWITCH.. THEN IT ACT LIKE IT WANTED TO MOVE WHEN I CHANGED THE TEMP ON THE REAR CONTROLS..
Expert:  Billy replied 5 years ago.
Ok...I dont think they are interchangeble so you will have to get the correct actuator and please Notice: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
Also it is possible that NOW you will have to replace both actuators.
If you can tell me what type of system do you have a can send some more info
(manual or automatic hvac)
and just to confirm, are you changing the rear hvac actuator.

Billy
Customer: replied 5 years ago.
I AM WORKING ON THE REAR HVAC LOCATED ON PASS. SIDE REAR NEXT TO THIRD ROW SEATS.. THERE ARE TO ACUATORS WITH LITTLE MOTORS INSIDE WITH GEARS IN THEM ALSO.. THAT OPEN AND CLOSE THE DOORS INSIDE THE REAR HVAC UNIT.. THE ONE CLOSEST TO THE FRONT OF UNIT CONTROLS FLOOR VENT OR ROOF VENTS .. THE ACTUATOR IN THE BACK OF UNIT CONTROLS THE TEMP. SETTINGS . THE REAR CONTROLS CAN BE TURNED ON BY THE DRIVER OR BY THE REAR PASSENGERS ... THE CONTROLS HAVE MANUAL OR AUTO ON THEM.. AND I DID HOOK THEM UP WITHOUT BEING ATTACHED TO UNIT.. WHOOPS WE NOTICED THAT SOMEONE OTHER THAN ME MAYBE A PREVIOUS OWNER MAY HAVE HAD PROBLEMS WITH THIS BECAUSE WE FOUND THE FUSE FOR THE REAR CLIMATE CONTROL THEY REPLACED O 10 AMP FUSE WITH A 30 AMP...
Expert:  Billy replied 5 years ago.
hello again,
Ok...so if you have powered up the actuator without installing them to the hvac module/box they are pretty much useless now. you will have to get new ones.
Both, the temperature control actuator and the mode actuator.
I assume you also had taken them apart, since now you now it has gears and motors inside of them : ). I really think you should get new ones for the rear. they have been giving all sorts of problems for us (techs) in the past anyhow.

So now you should disconnect the battery, replace both actuators (make sure they are bolted in place before proceeding any further) reconnect the battery.
Then perform the calibration procedure as follows.

If you feel my answer was helpful, please click the ACCEPT button. Feedback & Bonuses are always welcome.
Best regards,
Billy.

Actuator Recalibration

When replacing the HVAC control module it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC control module be sure to perform the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

  1. Place the ignition switch to the OFF position.
  2. Disconnect the scan tool.
  3. Install the HVAC control module.
  4. Connect all previously disconnected components.
  5. Start the vehicle.
  6. Wait 40 seconds for the HVAC control module to self-calibrate.
  7. Verify that no DTCs have set as current DTCs.

When replacing the HVAC actuator it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC actuator be sure to perform one of the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Preferred Method (w/ Scan Tool)

  1. Clear all DTCs.
  2. Place the ignition switch in the OFF position.
  3. Install the HVAC actuator.
  4. Connect all previously disconnected components.
  5. Start the vehicle.
  6. With the scan tool, initiate the Motor Re-calibration feature of the Heating and Air Conditioning Special Functions menu.
  7. Verify that no DTCs have set as current DTCs.

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Alternate Method (w/o Scan Tool)

  1. Clear all DTCs.
  2. Place the ignition switch to the OFF position.
  3. Install the HVAC actuator.
  4. Connect all previously disconnected components.
  5. Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
  6. Install the HVAC/ECAS fuse.
  7. Start the vehicle.
  8. Wait 40 seconds for the HVAC control module to self-calibrate.
  9. Verify that no DTCs have set as current DTCs.

Customer: replied 5 years ago.
WHY DO U THINK THEY REPLACED THAT FUSE WITH 30 AMP WHEN IT CALLED FOR A 10 AMP... I SPOKE WITH ANOTHER ASE CERT. MECH THAT DOES MY WARRANTY WORK AND HE SAID THOSE ACUATORS HARDLY EVERY GO BAD.. AND I WILL DEFINITLY GIVE U A BONUS...
Expert:  Billy replied 5 years ago.
Hmmm...did you say BONUS?
To show you that I'm hard at work for you and also better then the ASE certified technitian who does your warranty work ( AFTER ALL, I"M A GRAND MASTER TECH. FOR A REASON) : )
Im sending you a bulletin that may explain the original temperature control related problem that you were experiencing.
The bad news is that you will have to replace the two actuators as wel as the auxiliary hvac control module assembly.
So much for hardly ever going bad : )
Please read this information carefuly and perform repairs accordingly.
I will look into the fuse question, and get back to you.

#06-01-39-015A: Unable to Control Rear HVAC Temperature or Modes, Intermittent Ticking Noise from Rear HVAC Actuators or Rear HVAC DTCs B0434 or B3764 (Replace Auxiliary HVAC Control Module) - (Jan 12, 2007)
Subject:Unable To Control Rear HVAC Temperature Or Modes, Intermittent Ticking Noise From Rear HVAC Actuators Or Rear HVAC DTCs B0434 Or B3764 (Replace Auxiliary HVAC Control Module)
Models:2003-2006 Cadillac Escalade Models
2003-2006 Chevrolet Suburban, Tahoe
2003-2006 GMC Yukon Models
with Automatic Control HVAC System and Rear A/C (RPOs CJ2 and C69)


This bulletin is being revised to correct one of the blower motor control module part numbers. Please discard Corporate Bulletin Number 06-01-39-015 (Section 01 -- HVAC).


Condition

Some customers may comment on one or more of the following conditions:

An intermittent ticking/clicking noise from the rear Heating, Ventilation and Air Conditioning (HVAC) system.
Unable to control rear HVAC system temperature.
Unable to change rear HVAC system modes.

Technicians may find that Diagnostic Trouble Codes (DTCs) B0434 and/or B3764 have been set.

Cause

These conditions may be caused by HVAC actuators that hunt for the correct position. This cycling may cause a clicking or ticking noise.

An overtravel of the HVAC system control doors may cause one or more of the above system conditions. If an overtravel occurs, a DTC will be set, and the door will go to a preset default position.

When a system door defaults, that door will stay at the default position until the DTC is cleared. Clearing the DTC will allow the door to operate properly until the overtravel condition reoccurs. The following table lists the DTCs that may have been set and the door that is associated with that code.

Overtravel DTC

System Door Affected

B0434

Auxiliary (rear) Air Temperature Actuator

B3764

Auxiliary (rear) Mode Actuator

Correction

Technicians are to replace the auxiliary (rear) HVAC control module with the part number listed in the table below. Refer to the Auxiliary Heater and Air Conditioning Control Module Replacement procedure in SI for more information. This module contains a new calibration to compensate for the actuator overtravel condition and the hunting/clicking noises. The new calibration effectively eliminates DTCs B0434 and B3764. The new control module also eliminates the default position of the doors associated with the DTC. The new control module will allow door travel from counts 0 to 255 without setting a DTC or defaulting the door.

The new auxiliary HVAC control module is compatible with either the first or second design blower motor control module. When using the new auxiliary HVAC control module, the customer may notice a slight increase in the rear blower motor speed (approximately 50 rpm) at a given setting, as compared to the blower motor speed at the same setting with the original HVAC control module. If the customer comments that the increase in blower speed at a given setting is objectionable, the blower motor control module may be replaced with the second design part listed below to correct the slight increase in speed.

The revised auxiliary HVAC control module should not be used unless one or both of the DTCs are set or one or more of the conditions listed above are present. The revised auxiliary HVAC control module will not correct any other DTC or Air Conditioning (A/C) performance concern.

Parts Information

Auxiliary HVAC Control Module

Part Number

Description

Qty

15832319

Module Assembly-Auxiliary Heater & A/C Control

1

The blower motor control modules listed below should not be used unless the customer finds the change in blower speeds between the original and the new auxiliary HVAC control modules objectionable.

Blower Motor Control Modules

Part Number

Part Description

Vehicle Application

Quantity

89024926

Module Assembly, Auxiliary Heater & A/C Control (Auxiliary Blower Motor Control Module) (Second Design)

Escalade, Tahoe, Yukon (vehicles with a short wheelbase)

1

89018849

Module Assembly, Auxiliary Heater & A/C Control (Auxiliary Blower Motor Control Module) (Second Design)

Escalade ESV, Suburban, Yukon XL (vehicles with a long wheelbase)

1

Expert:  Billy replied 5 years ago.
rear hvac fuse IS NORMALLY a 30 AMP fuse.

Object Number: 879570  Size: FS
Customer: replied 5 years ago.
I UNDERSTAND REPLACING THE TWO MODULES.. BUT THE AUX HVAC CONTROL MODULE.. WERE THE HELL IS THAT... AND I HAVE NO TICKING NOISE. ONLY PROBLEMS CHANGING MODES AND TEMPS... I GUESS IF I NOTICE A SPEED UP IN AIR FLOW I CAN CHANGE HVAC CONT. MODULE...IS THAT WHAT THE BULLETIN SAID? DID I READ THAT RIGHT? AND I HAVENT TAKEN THE TRUCK TO HIS SHOP YET.. ONLY SPOKE WITH HIM.. I WISH I COULD TALK TO U ON PHONE... IT WOULD MAKE THIS A WHOLE LOT EASIER..
Expert:  Billy replied 5 years ago.
You dont necessary hear the a noise, read the bulletin carefully again.
(some MAY comment on ONE OR MORE of the following)

Some customers may comment on one or more of the following conditions:

An intermittent ticking/clicking noise from the rear Heating, Ventilation and Air Conditioning (HVAC) system.
Unable to control rear HVAC system temperature.
Unable to change rear HVAC system modes.

you were unable to control the temperature...correct?
The hvac control module is a small box at the back of the heater box.
This new moduel has a new calibration to compensate for the actuator overtravel and needs to be replaced (15832319 Module Assembly-Auxiliary Heater & A/C Control)

The other module in question is the blower motor module and READ THIS CAREFULLY as well-The blower motor control modules listed below should not be used unless the customer finds the change in blower speeds between the original and the new auxiliary HVAC control modules objectionable.

So in plain, replace
-two actuators
-updated rear hvac module (check new part number)
-rear blower module ONLY if you find the noise of the blower motor objectionable due to the increased rpm as per the bulletin.
Billy, Chevrolet tecnician
Category: Chevy
Satisfied Customers: 510
Experience: Over 25 years experience,GM grand master for 8 years,certified smog and government safety inspector
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