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2004 Suburban HVAC Heat/Cold Actuator Calibration Issues

08-30-2009, 11:40 AM
I have an HVAC issue that Iíve seen is common enough by posts out on different auto forums. The driverís side vent will intermittently blow hot and cold air regardless of the temperature settings. I found an actuator under the dashboard on the driverís side. I canít really see any others on that side without removing a whole lot more of the dashboard and items on the front of the dashboard Ė Iíve seen discussion on there only being two actuators for the front climate control and I seen diagrams showing more, such as two for the drivers and passengerís temperature, as well as actuators for defrost, floor/dash vent mode, and re-circulate. Iím not sure what the situation is for my 2004 suburban.

After much trouble at getting to it, I replaced the actuator that I could see. I disconnected the battery so as to leave the driverís side door open in order to get to this actuator. Iíve since found a slightly better way to get to it but not by much. I went through the actuator calibration processes that I see Ė mainly pulling the HVAC/ECAS fuse and then letting the climate control cycle through. Iíve done this several times.

The results are that the driverís side now only blows hot and all front vents only blow through the defrost vent (steady state after about a minute). However, as the calibration process occurs, cold air will blow out of all of the front vents for a few seconds and then will go to defrost. I canít do anything to correct this. All of the rear vents work correctly.

Iíve seen the TSB 04-01-38-008 on the DSTs of B0229 (re-circulation actuator), B0414 (left air temperature actuator), B0424 (right air temperature actuator), and B3770 (mode actuator). Iíve checked the wiring harness and notice that there is a woven sheath around it to protect it Ė looks like it was addressed at least by 2004. It is possible that I might have at least one of those codes Ė Iím not able to check it. Iíve disconnected the battery to try to reset.

It seems that my problem is more a calibration problem and not an actuator problem (part not working). I tried to be careful in putting the new one on exactly as the old one came off.

Any ideas on what the problem is and how I can correct?

09-01-2009, 07:34 PM
This actuator mounts horizontally on the unit to which it is attached - the rounded part of the unit is to the right and the connector is on the left side if looking from the brake pedal towards the actuator. there are three markings to the right of the hole - one is horizontal with another maybe 20 degrees above and the last twenty degrees or so below. The notch in the actuator gear starts out below the lower mark.

When I start the car for the first time to calibrate, it travels to about the top mark and there is air coming outside the front vents. It then travels back to the original starting place about 10 degrees below the lower mark and shifts to blowing out of the defrost vents. No matter what I do with the climate controls, it continues to blow out the defrost vents.

I'm starting to wonder if the shaft maybe traveled 180 dgrees on me before I got the new actuator on when I replaced it - maybe it have traveled as far as it can go in one direction. If I get no responses, I might try 180 degress counterclockwise. I'd would be nice to know something from someone who has been through this as it is very difficult to remove and resinstall.

It appears that I replaced an actuator associated with the front/defroster vents and that the driver's side temperature actuator is somewhere else?

Thanks for any advise ...

09-06-2009, 05:35 PM
I also have a 2004 suburban and I'm experiencing the same issue with the driver's side air switching randomly to hot air. It resets when I shut the truck off and restart. I haven't found the right solution yet, though a lot of the talk I've seen on other forums say to replace and/or calibrate the blend door actuator. Please let me know if you come up with the right fix, and I'll do the same.

09-09-2009, 07:08 PM
I had that same situation as you. It would not always reset immediately but eventually would.

After replacing the driver's side actuator, I drove around for 3 or 4 days with it working as described above. My autobody repairman offered to have an ac tech that he said was a former gm tech look at it.

On the way to driving there, I noticed that it was all working correctly. I played around with the controls for 15 minutes and it all worked correctly. I postponed having the tech look at it.

My battery died today. I'm right back where I started - hot air only and defrost only. After playing around with the controls for a while, I've got cold air blowing, but no front vents - defrost only.

I'm convinced I have a calibration problem and I suspect that there's more to it than what I've seen on the web, or I'm not understanding the procedures correctly. It really aggravates me that disconnecting the battery for any reason resets it out of whack.

09-14-2009, 05:20 PM
well this must be common i would love to find a resolution, i have an 04 Avalanche and Same issue goes to hot on driver side and will not work until i turn truck off and restart.

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