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HVAC actuator

Tiny
FRANKALONG
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 6.6L
  • V8
  • 4WD
  • AUTOMATIC
  • 123,000 MILES
Replaced all the actuators for HVAC. For the recirculating door have tried two new actuators and after calibrating, each actuator goes out of its range and stays there. The control is the auto type.
Friday, April 13th, 2018 AT 10:03 AM

25 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

Below is the description of when the mode door will operate.

Can you check the pressures listed?

Roy

The HVAC control module controls the air intake through the re-circulation actuator. Re-circulation is not available when the mode is in defrost. When the mode is in defog, re-circulation will only be available for ten minutes. The operator must activate the blower for re-circulation operation. The A/C high-pressure re-circulation switch can cause the HVAC system to recirculate air. If the re-circulation switch is pressed into the "on" position when the mode switch is in an unavailable mode position, then the re-circulation switch LED will flash three times. When the high side pressure reaches 2206-2620 kPa (320-380 psi), the PCM will place the HVAC system in re-circulation mode. The high side pressure is lowered when the inside air cools the refrigerant within the A/C evaporator. When the high-side pressure reaches 1447-1861 kPa (210-270 psi), the PCM will place the HVAC system out of re-circulation mode.
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Saturday, April 14th, 2018 AT 5:31 AM
Tiny
FRANKALONG
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Hi Roy.
Not able to check pressures.
Continuing to diagnose, was able to determine that the recirculating actuator was over traveling and preventing door operating after engine restart. Probably set a DTC. Appears the foam on the recirculating door took a set and allowed the actuator to move further toward its limit. GM has a bulletin to reprogram the actuator.
I covered the door with thick poly using adhesive. It prevents the actuator from over traveling. Seems to work.
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Sunday, April 15th, 2018 AT 1:50 PM
Tiny
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Okay.

Did you calibrate the actuator?
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Sunday, April 15th, 2018 AT 1:57 PM
Tiny
FRANKALONG
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I did not (cannot) re-calibrate do not have the correct scan tool to change actuator limits. I changed the limits by increasing the door thickness slightly, thus reducing the door travel distance. The door closes and seals fine.
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Sunday, April 15th, 2018 AT 5:23 PM
Tiny
FRANKALONG
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Also, if the actuator was positioned at a different degree relative to the door shaft, the travel distance would be more centered within the actuator. And not be near the limits.
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Sunday, April 15th, 2018 AT 5:31 PM
Tiny
ASEMASTER6371
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Calibration is easy and no scan tool required.

Remove the fuse for the AC control head for ten minutes.

Then insert the fuse and turn the key to the on position. Wait one minute and the actuators are calibrated.

Also, the control knows the limits by current draw when the motors hit a restriction. It has nothing to do with stops. It is about current draw.

Roy
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Sunday, April 15th, 2018 AT 5:45 PM
Tiny
FRANKALONG
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Hi Roy
I thought you meant calibrating to new limits.
I did the calibration per your method already. Did it several times. Result was the same. Actuator went to its limit and would not move in opposite direction.
So I went through the †backdoor’, (haha) and shortened the door flap distance, thereby shortening the actuator travel.
Adding the poly to the door was a little tricky but it works!
Repositioning the actuator itself would be challenging but not impossible.
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Sunday, April 15th, 2018 AT 6:22 PM
Tiny
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It should not do that at all.

I am concerned about the actual actuators.

Roy
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Sunday, April 15th, 2018 AT 6:30 PM
Tiny
FRANKALONG
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Well, I tried two new actuators and both reacted the same when used with the original door. Door would work until key turned off. After key turned back on door would not move.
After modifying the door, it works after key turned off then back on.
GM had a bulletin out 06-01-38-003 possibly regarding this situation.
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Monday, April 16th, 2018 AT 4:44 AM
Tiny
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Okay.

Are there any codes in the HVAC module?
Roy
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Monday, April 16th, 2018 AT 4:49 AM
Tiny
FRANKALONG
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My scan tool is very basic. No codes registered.
Plan on getting a better scanner. Any suggestions?
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Monday, April 16th, 2018 AT 6:03 AM
Tiny
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Snap on, OTC, are a couple good ones. Look for them on Amazon and eBay.

Roy
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Monday, April 16th, 2018 AT 6:06 AM
Tiny
FRANKALONG
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  • 15 POSTS
Thank you.
Enjoyed the discussion!
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Monday, April 16th, 2018 AT 9:17 AM
Tiny
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You are welcome.

Glad to help.
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Monday, April 16th, 2018 AT 9:58 AM
Tiny
FRANKALONG
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  • 15 POSTS
If this is still Roy, have an update on the air actuators of my 2004 Silverado.
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Monday, April 30th, 2018 AT 5:18 PM
Tiny
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Yes, I am here.
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Monday, April 30th, 2018 AT 5:30 PM
Tiny
FRANKALONG
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  • 15 POSTS
Hi Roy
I thought I had the re-circulation door working, but it stopped after a few days. Apparently the added foam was not enough and the actuator went beyond its limit then stopped working.
So yesterday dash comes apart again. This time I added more foam and also changed the actuator stop limit position so the actuator electrical connectors on the gear would stay close to within the desnigated range.
If the actuator was positioned differently relative to the door shaft, the range would match the door range.
Is this an inherent problem with this truck or can the actuator range be changed via computer adjustment?
Frank
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Monday, April 30th, 2018 AT 7:45 PM
Tiny
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Okay, no adjustment at all with the control head.

It sounds like the housing is worn from your description. Look carefully for any wear.

Roy
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Tuesday, May 1st, 2018 AT 3:39 AM
Tiny
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The housing is molded into the plastic and cannot be moved. The actuator fits tightly and screws into the housing.
Could GM have misdesigned? Maybe a later fix?
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Tuesday, May 1st, 2018 AT 4:37 AM
Tiny
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There has to be a reason for the doors moving too far.

No, no updates that I could find at all.

They may have but will never admit it. Do not see any updates to the housings.

Roy
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Tuesday, May 1st, 2018 AT 4:40 AM

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