09 Gmc Climate Control Question

[pss3757]

Has anyone figured out exactly how the recirc is supposed to work. WHat i mean is, that sometimes it stays on, sometimes it doesnt. SUch as: (all using AC with main body fan direction)

 

1) in the morning...cooler climate....turn on truck and it is in fresh air mode, turn to recirc. drive to store, then come out and restart...now in fresh air mode again.

 

2) hot summer afternoon....go out to start truck....its in recirc mode. Drive to store, come back out and start up....still in recirc mode.

 

3) start it up in the morning...fresh air mode, change to recirc. Drive for a good while....get out and let it sit (cool off)...restart, now in fresh air mode again.

 

Whats the deal?? Not a problem, but a mere inconvenience. I like it to stay in recirc mode.

 

It seems like it has to do with the outside temp....call me crazy.

[Jsdirt]

I think you just read my mind!

 

I had the same questions when I bought my '07 Silverado new body. Unfortunately that's the way the unit is programmed. I thought there was a filter in this vehicle as I had heard previous years had very expensive filters -- so I figured this is how they make some extra dough at our expense. But there isn't a filter -- it only goes to recirc mode during heavy load periods -- like on a hot summer day parked in a wide open lot. As soon as it comes down to temp setting, it goes to outside air. I think the only way to avoid that is to not use "AUTO" mode -- but it's a great feature. It's on in my truck constantly. I used to just hit the recirc/outside air button every time I got in the truck after work in the summer -- when the truck was new. Now I just gave up -- I don't care where the air comes from, as long as I'm comfortable!

[68haywagon]

It's not just our trucks, my mom's new malibu does this too.

 

Mike

[bill190]

A GM factory service manual HVAC "description of operation" should say how it is supposed to work.

 

Does it say anything in the owner's manual about this?

 

I'm just "educated guessing" with the following...

 

Older vehicles are going to work different from newer vehicles.

 

And newer vehicles with a more "wiz bang" system are going to work differently than a basic system.

 

But if you have a new vehicle with the "wiz bang DELUXE" auto A/C system, then this is going to have about 5 different temperature sensors. One might be for "sun load" another for outside air temperature. And others for various spots inside the vehicle.

 

Then this will be computer controlled. And with a computer, they can program it to do whatever they want.

 

And what they would want is for the vehicle to cool off as fast as possible. So if the outside air is cooler than the inside air, they would want recirc off and to bring in that outside air to clear the hot air out of the vehicle. But if around the same temperature outside as inside or hotter outside than inside, then the vehicle will cool off faster on recirc.

 

Older and less "wiz bang" systems might always start with the recirc off assuming that the outside air will be cooler.

 

Then in a car I have with manual controls, I have to do this myself. If it is cooler outside and real hot inside, I switch it to fresh and open a window to get the hot air out. Then when it starts to cool off, I roll up the window and switch it to recirc.

 

If you want to know more about this, might ask at the following forum. This is located in Arizona where it can be 120 degrees some days, so they know their A/C stuff!

http://www.autoacforum.com

[prioritypest]

Everytime i start my truck its on outside air, 110+ here and sometimes while driving it will jump from recirc to outside air. Never should of bought black on black in AZ

[pss3757]

A GM factory service manual HVAC "description of operation" should say how it is supposed to work.

 

Does it say anything in the owner's manual about this?

 

I'm just "educated guessing" with the following...

 

Older vehicles are going to work different from newer vehicles.

 

And newer vehicles with a more "wiz bang" system are going to work differently than a basic system.

 

But if you have a new vehicle with the "wiz bang DELUXE" auto A/C system, then this is going to have about 5 different temperature sensors. One might be for "sun load" another for outside air temperature. And others for various spots inside the vehicle.

 

Then this will be computer controlled. And with a computer, they can program it to do whatever they want.

 

And what they would want is for the vehicle to cool off as fast as possible. So if the outside air is cooler than the inside air, they would want recirc off and to bring in that outside air to clear the hot air out of the vehicle. But if around the same temperature outside as inside or hotter outside than inside, then the vehicle will cool off faster on recirc.

 

Older and less "wiz bang" systems might always start with the recirc off assuming that the outside air will be cooler.

 

Then in a car I have with manual controls, I have to do this myself. If it is cooler outside and real hot inside, I switch it to fresh and open a window to get the hot air out. Then when it starts to cool off, I roll up the window and switch it to recirc.

 

If you want to know more about this, might ask at the following forum. This is located in Arizona where it can be 120 degrees some days, so they know their A/C stuff!

http://www.autoacforum.com

 

Is there a gm tech somewhere in the forum that can clear up the matter on how the climate control system is supposed to work....just for peace of mind??

[omegafiler]

The manual pretty much says that while in the Auto setting, this is all done on it's own based on temp you set as well as the interior/exterior temp and solar sensor on the dash. Once you push one of the manual control buttons, it should take it out of auto mode, which is possibly why it may not change again until you hit Auto or play with the settings.

 

This is basically how it's worked on all of the recent vehicles I've owned with the automatic climate control system. I know it can appear to have a mind of it's own at times... but that's because it does have a mind of it's own.

[Fyrcaptain]

You actually read the manual?.........lol....

 

 

The manual pretty much says........

[omegafiler]

You actually read the manual?.........lol....

 

 

The manual pretty much says........

 

 

Well, parts of it.

 

I have it in PDF format, so it's much easier to search for what you want rather than dig through the book.

[Darkanion]

Well, parts of it.

 

I have it in PDF format, so it's much easier to search for what you want rather than dig through the book.

Hrmmmm.. That could be handy.. Got a link??

[pss3757]

Well, parts of it.

 

I have it in PDF format, so it's much easier to search for what you want rather than dig through the book.

Hrmmmm.. That could be handy.. Got a link??

 

 

really.....can i pm you for a link?? sure could use it.

[brims]

You need to sign up for mygmlink.com which is now some Yahoo service.

 

If you have the heater on, it won't let you go into recirculate because it blows out the bottom vents. Not sure if that helps anyone.