Just like the title says, my a/c only comes out of my defrost vent and it doen't matter what setting you put it in. I found a hole in the hose behind the battery and reaplaced it, problem still there any other ideas? Thanks in advance.

 

you either have a vacuum leak of a faulty mode vacuum actuator

also we only allow one thread per subject, so i deleted the one in the 97-03 section. Thanks for your cooperation

 

Does it change if the truck is under acceleration? Mine is doing this, I have the electronic temperature control module. I am going to look for vacuum leaks under the hood and if nothing , ill try the o-ring replacement. Might want to check that out.

 

No it does not change under accerleration, I will look into it as well thanks.

 

Ok did not know that, where is the mode vacuum actuator located? Thanks for your help.

 

i also have this problem

 

1 — Steering wheel remote control switch assembly
2 19D888 In-car temperature sensor
3 19E663 Sunload sensor
4 19980 EATC module
5 18A318 Air inlet door vacuum control motor
6 19E624 Blower motor speed control
7 19E616 Temperature blend door actuator
8 18A318 Panel/floor door vacuum control motor
9 18A318 Panel/defrost door vacuum control motor
10 19E561 A/C cycling switch
11 19D594 A/C pressure cutoff switch
12 12A647 Ambient temperature sensor


you can check the incoming vacuum by pulling the control panel out, and it should be the center vacuum tube. You can also check all the mode doors by applying vacuum to each tube with a vacuum pump.

 

I fixed mine!!! it was a corroded vacuum line behind the battery

 

I do have this problem also. It started only under acceleration now it is 99.9% of the time. In addition to this I had a small accident in the snow last winter and coffee went everywhere including into the control module now the fan goes on and off by it's self. I think someone kind of contact cleaner would help. Can some give a little better description of the vacuum hose behind the battery etc... or how to remove the module from the dash? Thanks

 

Open the hood. Look for the small vacuum line routed near the battery that goes from the intake through the firewall.

 

I have a 2002 with the same basic issue. Blows out the panel all the time unless it is on max A/C, with the fan on low under acceleration, then it goes to defrost. It has an EATC unit, which has been replaced. The vacuum reservoir had a hole in it, so that was replaced. I am getting pretty good vacuum draw at the back of the EATC.

Can anybody tell me which vacuum lines go to what at the back of the EATC?

I appreciate your help

 

I finally found which vacuum lines go to which actuator.

I pulled the EATC, left the electric hooked up, disconnected the vacuum line harness. The air continued to come out the panel. I would have thought it would have defaulted to the defrost. I jumped vacuum lines from the black to each of the others, the air continued coming out the panel. Put it all back together and went for a ride.

Same as before, comes out the panel and if the fan is on low it will go to defrost on acceleration.

really confused now.

Help please.

 

Just found that the panel door in the dash is just flopping in the breeze. Now I just need to find out if it is the motor or connection or some combination.

 

(2003 F150 HD Supercharger)
I am having this same issue currently...did you figure out your issue?

 

Same issue as who?