05 Silverado temp door problems.

CarnageRacing00 · August 6, 2018

Non-automatic HVAC, dual climate zones.

So here's the back story.

I bought this truck in 2015 and from day one it's had this issue where, when running the AC, the driver's side ONLY would randomly switch from cold to hot. The only way to reset it was to restart the engine, and it would go back to cold. Sometimes this would fix it for hours, sometimes for days, and then sometimes it would only last a few minutes before it happened again.

I've dealt with this issue for 3 years because it didn't bother me enough to fix. I have had my battery disconnected several times for other reasons since and it never had any effect on the problem, so I'm not sure if re-calibration would have helped.

Anyway, just yesterday my alternator failed. It didn't kill the battery as I managed to turn around and get home before that happened, but after installing the new alternator, the problem with the cold turning to hot became a million times worse - it would now happen within second of starting the truck, every single time. Whereas I used to be able to restart the truck and enjoy cold air for minutes to hours to days, now it would go right back to hot after just seconds, and this happened after several restarts, and a battery disconnect.

So, I figured it's finally time to replace the temp door actuator.

Assuming I'm identifying the part correctly... it's the actuator on the driver's side of the trans tunnel, up under the dash. You have to remove the gauge trim panel, the lower knee bolster, disconnect the vent duct and there are two 7mm screws that hold it in. It's mounted on a shaft that rotates a large pie-shaped piece with gear teeth on it. When I pulled the actuator off the shaft, the gear piece pulled away from the door assembly. I had to realign it.

That is the Driver's Side Temperature door actuator, correct?

Ok, so I replaced it. Turn the truck on, AC is blowing ice cold from both sides, drove the truck around, no problems at all. I can change the temperature to heat, and it starts blowing heat. Back to cold, starts blowing cold. All is well. ICE cold, HOT heat.

Then I noticed a small, circular shaped return spring laying on my floor mat. It MUST have come from the gear/door assembly... but it's changing from hot to cold just fine.

So then I realized that it's no longer switching between the modes. It stays blowing out the front vents only. When I switch modes, the strength of the air will weaken slightly, but it will not change to Defrost or Floor or Bi-Level or anything. This was never a problem before.

Now, obviously the simple answer is to reinstall the spring. Except that I have no idea what position it goes in because I didn't see it come off.

And apart from that, I'm also curious about how the whole system works together. I was under the belief that the individual climate zone temperature doors and actuators wouldn't be connected to the mode door? Since there is a single mode control? So why does the fact that this spring is missing mean that the mode door is apparently no longer functioning? Or did I replace the wrong actuator to begin with, and it's just a coincidence that my cold to hot problem isn't happening since I did it?

And how is it supposed to be situated, so that when I go to reinstall it, I don't put it in wrong? Help would be very much appreciated.

Doug_Scott · August 7, 2018

No idea on where it goes, but I can help with the basic understanding part.

The vacuum motor can only pull in one direction, so the spring will return the door to its "home" position. If you watch the servo move the door, you figure out which way it needs the spring to go.

txab · August 7, 2018

Actually if the drivers side temps are affected it's the actuator on the passenger side above the trans tunnel. Looks like you replaced AC Delco #1573952. It's listed 2nd from the bottom in the Rockauto parts lookup. Read the description for the the referenced part. By replacing the alternator, disconnecting the battery, you did a re-calibrate procedure on all the actuators. Your temp problem will probably return

Quote

ACDELCO 1573952 {#89018374} GM Original Equipment Info

Fits Mode Door (Controls which vents the air comes out of); Left; Front; Dual Zone Climate Control with Automatic Controls (you can set a specific numeric temperature) (CJ2)
Or Mode Door (Controls which vents the air comes out of); Left; Front; Dual Zone Climate Control with Manual Controls (blue/red dials only); EXCEPT Custom Floor Compartment Floor Console (D07)