GM Savana 3500 A/C Stuck On Defrost/Floor

[GMCSavana3500]

Hello, we are a family with eight kids with one on the way. We bought the 2003 15 passenger Savana to haul the kiddies around. It has been a trouble free and great vehicle to have. So, here is our first trouble, the a/c is stuck on blowing air through the defrost on the dash and the floor vents. It will turn off/on with the control knob, but no matter what selection is made for where to send the air, it stays on defrost and floor. Now pregnant momma is not staying cool down here in SW Florida in July with the cool air blowing everywhere but her.

 

I have started the troubleshooting process and I have all of the plastic dash covers off. I have to also say that I am an emergency generator technician, so I have troubleshooting experience, but vehicles are a different creature.

 

I have also pulled out the control assembly for the a/c knobs and I have noticed that it works on some sort of vacuum tube control for the vent choice. I also found the vacuum assembly in the far forward, right (passenger) side dash. It has two vacuum lines attached to it. I pulled the tubes off and removed the assembly. It moves freely and doesn't seem to be stuck. I inspected the spring-loaded arm that attaches to the vacuum assembly so with the van running and a/c on, I can see that it opens and closes the vent for the defrost.

 

I cannot find the vacuum assembly for the dash vents. I have to assume that there is a problem with one or two of the vacuum lines that controls the on/off for the defrost-floor vents and the on/off for the dash vents. Or there is a problem with the dash vent vacuum assembly, since I have not found it yet. That is where I am now and I have started the process of the good ole "internet search".

 

I found this website and I hoped to receive some helpful ideas. I know that you guys have GM "Trucks", but everytime I lookup service parts (filters, etc.) for the Savana, they are listed in the Trucks section.

 

God Bless you guys and I hope everyone is having a great summer.

 

Woody

[GM-Tech]

Loss of vacuum to the ac control causes the system to default to defrost mode. So the first thing you need to check is to make sure you're actually getting vacuum supply to the control.

 

If no vacuum, there's a vacuum reserve tank under the hood somewhere (maybe even the under a fender), which can become disconnected or damaged. I'm not really sure where it is, having never had to work on this system on that vehicle.

[GMCSavana3500]

Thank you for the heads up on the vacuum pump. I have moved alittle further in my troubleshooting and have located the vacuum diaphram assembly for the front vents. I can reach the arm coming out of it with a long screwdriver and I can move it so that air blows from the front vents. As soon as I let it go, it swiftly sucks back in and sends the air to the defrost. I am now off to inspect the vacuum pump that you mentioned and hope to find a quick resolution.

 

Thanks again for your help and God bless.

 

Woody

[GMCSavana3500]

Loss of vacuum to the ac control causes the system to default to defrost mode.  So the first thing you need to check is to make sure you're actually getting vacuum supply to the control.

 

If no vacuum, there's a vacuum reserve tank under the hood somewhere (maybe even the under a fender), which can become disconnected or damaged.  I'm not really sure where it is, having never had to work on this system on that vehicle.

 

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Ah, you are right on! I checked out the two vacuum lines coming from behind the firewall and there is a lack of vacuum. The black line splits off and connects to the control knob selector. I sucked on the black line and the a/c air changed over to the front vents when I applied a vacuum on the line. When I let it go, it went right back to defrost.

 

Now, I know that you mentioned the vacuum reserve tank and where to look, but what does it look like? Will it be a black plastic tank, metal can or part of other A/C componet? In the mean time, I will try to back track the lines through the firewall until I find something.

 

 

Thanks a million, Woody

[timothyklick]

Woody,

 

I am experiencing the same exact issue with my 06 savana... have you been able to locate the reserve tank yet??? If so were you able to fix the problem? Any help would be great!!

 

Tim

OneSeventeenAV

[sierradenali11]

sometimes the plastic ball vacuum tank is located in the engine compartment, sometimes underneath the fenders, behind the plastic black inner fenders. im not sure if it is there on your van, but thats a typical location