AC is stuck on defrost.

I pulled out and replaced the switches and it didn’t fix it. I have no holes in the hose at all under the hood. (I smoke tested it). I changed the AC actuator and noticed that motor works for the heat/cool switch. I can’t figure out the problem.

Is there a motor similar that works the middle switch for defrost and AC? Maybe that motor is bad? I can’t figure it out. Any help would be great. Thanks

 

There is a check valve in the heater supply line right where it tees off next to the trans dipstick that won't allow pressure from the smoke test to enter the heater. That black plastic hose may be broken under the dash. It runs to the plug on the back of the mode switch in the panel. The mode switch directs airflow to different outlets. It is strictly vacuum operated, but has a switch on it to turn off the low speed fan when turned to off.

 

I see where the little black hose goes through the firewall. So yeah that hose could be broken somewhere inside the dash. Thanks for the information I’m not really sure what you are suggesting lol. Look for that mode switch?Look for that mode switch?

 

I replaced the dials, if that what u mean by mode switch. But I didn’t replace any of the original wires going to it. I just took off the panel with the 3 dials and put a new one on.

 

I pulled those 3 switches out and plugged a new one into those wires behind that

 

So I decided I’m just going to order all new vacuum lines just in case there is a hole that I’m not seeing. Problem is I can’t find it anywhere online

 

Does anyone know what these colored wires do? Regardless if I have them plugged in or not it does nothing for the dial currently. Its always on defrost. Should they have suction luke the line coming from my vacume ball does under the hood? That line is sucking well. Wasn’t sure if these colored lines were electric or vac lines as well.

 

There is no leak in the vacume lines. I pull the line off the ball in the bumper and it has good pressure. It’s sucking great. Still don’t know what the issue is.

 

If you have "pressure" in a vacuum system you have a problem!

 

Those "wires" are vacuum lines. If you have nothing but defrost it's likely you have a vacuum leak between that selector and the connection in the engine bay. If you had air out of the vents until you accelerated then I'd say it is the check valve acting up.

Did it used to work, or has it always been this way?

 

Could be as simple as a vacuum hose popped off a nipple. Happens very easily

 

No I only have air out of the defrosters.


I checked under the hood, there’s no leak in that vacume line. It’s sucking very well off the the vacume ball in the bumper.

 

Yeah my AC used to work normally now it only comes out of the defroster vent.

 

Here's where you oughta be looking:

 

If I take the hose off the vacume ball in the bumper I can feel it sucking like it’s supposed to. There’s no leak in that line.