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2004 chevy tahoe Z71: V8..an intermittent AC problem..drivers side…

I have a 2004 chevy...
I have a 2004 chevy tahoe Z71 5.3 V8. I am having an intermittent AC problem on the drivers side. The air conditioner works fine on the passengaer side and and the rear AC has no issues either.
What happens is sometimes it just starts blowing very hot air. I mean like 85 degrees hot like someone just turned the heat on. If I pull over turn the car off and re-start it in about about it works again. It could be an hour or a few days before it happens again.
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Answered in 4 minutes by:
6/25/2010
Ted G.
Ted G., ASE Certified Technician
Category: Chevy
Satisfied Customers: 6,226
Experience: 20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
Verified
Your HVAC system is controlled by a self diagnosing computer system. You will need to take it to a shop that has a scanner capable of scanning and testing the system. Many good independent shops and all dealers will have this. There will be a code set in the system that will lead the tech to the failed part, likely an actuator, but there are several other parts that could be failed, so a scan is the best way to start. When you turn the truck off you are resetting the system so it begins to work again, but there will still be a fault code stored.
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Customer reply replied 8 years ago
Can I use an OBDII scanning tool? I work on cars a lot and I'm an okay shade tree mechanic who has a good basic understaning. I did use this service back in february to trouble shhot and repair the rear AC. It ended up being the rear module part number 15832319.

So if you want to trouble shoot with me I will keep going with you, but take it to a shop to repair is not an answer that helps me.
No, an OBD scanner cannot access the body control module and that is how you get to the HVAC system. Even if you want to replace the parts yourself you are going to need it scanned first.
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Customer reply replied 8 years ago
Relist: Incomplete answer.
Hal
Hal, Chevy Master Tech
Category: Chevy
Satisfied Customers: 1,032
Experience: ASE and Chevy Master , 31yr Dealership exp,
Verified

Hi My name is HAL.

Sounds like yo have a very intermittent concern. The trouble code would help greatly in diagnosing this concern, You need a scanner that can read the HVAC module.

 

With out the information in the HVAC module available, all I can offer is some of my experiences with this type of concern.

 

First, the most common would be the temp actuator. It is located on the bottom of the HVAC case, on the passenger side,( looks kind of like a triangular shaped motor ,one connector and held on by two 5mm head screws.

 

Second . The aspirator just above the drivers seat. can cause these symptoms.

Makes temp control very sensitive on driver side.

 

These are the two most common that I have seen.

 

There is just no other way to diagnose these concerns without seeing what the computer See's. All diagnoses starts with a check of the codes. If that is not an option for you then I can understand that. The diagnostics all work from being able to view data.

 

I hope this will get you started. I have seen several concerns corrected with the above repairs. Both of these Items are fairly easy to replace.

 

If you need more information, I will give you the best of my experience that I can to help you out.

 

I'm including two diagrams, One of the temp actuators and one of the temp sensor aspirator

Thank you HALgraphicgraphic

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Customer reply replied 8 years ago
do you hvae part numbers so I can deterime their costs? if they are too expensive I will replace tghem both and pay you for your suggestions.

Also I read that removing the AC fuse under the hood would cause the actuator to recycle through hot and cold and make fix it.

Thoughts?

When you disconnect power from the HVAC module, It may recalibrate, or lose calibration. The rear temp mode actuator goes through a recalibration every time power is cycled. The fronts do not, They can be recalibration so the HVAC module knows what position there in. A scan tool is needed to do this.

 

I would replace the aspirator first. They can do some weird things. It is a fancy name for an inside air temp sensor.

Aspirator #15029252 approx $40.00

The temp door actuator #89018365 $ 263.56

 

Air Temperature Actuator

The air temperature actuators are a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference, control, 5-volt reference and position signal circuits enable the actuator to operate. The control circuit uses either a 0, 2.5 or 5-volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5 volt control signal commands the actuator movement in opposite directions. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 volts.

The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted, value, the control signal is changed to either 0 or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.

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Customer reply replied 8 years ago
Thanks fpr trying to work with me I sincerely XXXXX XXXXX I did replace The temp door actuator (Advance Auto had it for $135.

My AC is working but it was workingbefore I just didn'y know when it might go out. I have been on 4 forty minute plus drive and so far so good.

I would like more infornation and where to find the Aspirator #15029252 I can't locate it. Can you give me some very detailed instructions of how to locate it? I would like to pay you before the weekend is over. Thanks!

The aspirator can be purchased through the GM dealer, or gmpartsdirect.com. The part number is XXXXX GM part number. (15029252 changes to 25771194)

To replace it, is very simple The little grill above the drivers seat in the headliner is the inside air temp sensor( aspirator) You remove the left A pillar trim( pull straight out, to you. there is one large metal clip that hold it on) Remove center pillar trim. remove rear assist handle. remove left sun visor.

Pull the weather strip down from the top around the door.

Reach in and disconnect the aspirator connector and unsnap the little grill off the aspirator.

Reassemble in reverse order. I will include the service manual instructions and some pictures

These are very difficult to diagnose unless it is acting up, at the time you are checking it.

 

Removal Procedure

  1. Remove the left windshield garnish molding. Refer to Windshield Pillar Garnish Molding Replacement .
  2. Remove the left center pillar assist handle. Refer to Roof Rail Rear Assist Handle Replacement .
  3. Remove the left center pillar garnish molding. Refer to Center Pillar Garnish Molding Replacement .
  4. Remove the left sunshade. Refer to Sunshade Replacement .
  5. Gently pull down the headliner.

  6. Object Number: 675996  Size: SH
    Click here for detailed picture of above image.
  7. Disconnect the electrical connector from the inside air temperature sensor.
  8. Partially remove the inside air temperature sensor from the headliner.
  9. Remove the sensor grille from the inside air temperature sensor.

  10. Object Number: 675994  Size: SH
    Click here for detailed picture of above image.
  11. Remove the inside air temperature sensor from the headliner.

Installation Procedure

  1. Install the new sensor grille to the headliner.

  2. Object Number: 675994  Size: SH
    Click here for detailed picture of above image.
  3. Install the inside air temperature sensor to the headliner and sensor grille.

  4. Object Number: 675996  Size: SH
    graphicgraphicgraphic
Hal
Hal, Chevy Master Tech
Category: Chevy
Satisfied Customers: 1,032
Experience: ASE and Chevy Master , 31yr Dealership exp,
Verified
Hal and 87 other Chevy Specialists are ready to help you
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Customer reply replied 8 years ago
Thanks that acually looks harder than than the other one. I will keep this and see what happens. I will pay you now thanks.

Looks worse than it really is, It is pretty easy once you get started.

Thank you, XXXXX XXXXX your 4th was great.

Hal.

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