ac blows out the defroster ducts

[JP02XLT]

Defrost is the default "fail" position for the system to go into, Why? so that in the worst case you have a system that will still clean the windows, & the heat/Ac system will not be responsible for fogged windows & blocking your vision.

JP02XLT

 

[Big Jim M]

The switches rarely fail. There is about a 99% probability that you have a hose leaking. Almost always the leak is under the hood. Many times it is the cannister itself that is unplugged. While the engine is idleing pull the hoses from the engine toward the cannister and then at the outlet of the cannister and then where the hose goes into the firewall. You will be holding your finger over the hose you disconnected to find the same amount of vac as the first hose you pulled.
We can't do this for you! You gotta do more than stand in front of the vehicle and drink another beer! Get down and dirty with it and you can repair it yourself.
Big JIm

 

[modelageek]

Lol. You mean you can't fix these things by osnosis

 

[tobyduck]

I have the same problem on a 98'. I have a break down book on the truck but they failed to explain this. The vent is like in between defrost, floor, and a smidge of vent...just barely enough to notice. I just replaced the engine in it and all of the vacuum lines are installed properly. I'm really confused on the subject and I think that it could be a main vacuum line but I don't know how to test for it. It's under the coolant and wiper reservoir isn't it?? But there are two and one is black but it looks like it may be dry rotted or it just got broken in half somehow. idk

 

[Big Jim M]

There should be only ONE hose going INTO the firewall.. PUT some vac on that hose and see if the system works when the vac is on there.
Big JIm

 

[tobyduck]

it's hooked up, and the vacuum hose to the engine works. I can suck air out of the hose for the A/C but I tried to blow through it and I can't. I'm sorry, I'm still confused on the subject

 

[crf250r6]

its a switch, happend to my buddys.

 

[NewEngine]

Thanks to Big Jim M and JP02XLT, I used both your suggestions. My truck's problem was the air stopped blowing out the front vents on the dash. Floor and defroster would all work when I moved the switch, but when set to AC and Max AC, the cold air would only blow out the defroster vent in the dash on top the windshield.

I traced the hose going to the firewall back to the vacuum ball, and pulled the end off the vacuum ball and sucked on it, and there is a leak. Removed the wheel well cover on the passenger side to inspect the hoses where they go into the firewall, everything looks good. I then went up under the dash behind the glove box and disconnected the vacuum connector with the five hoses. I then took a piece of spare tubing and worked my way around the white connector, blowing and sucking on each line one at a time. If you listen carefully, you can hear each diverter or piston reacting to the vacuum.

Hooked it all back up, and my front vents now work. Don't know for how long, but its a start. I'm in Florida, so I will just leave the switch to Max AC for the next 5 months anyway. I still feel a leak when sucking on the firewall hose, but I don't see how to change out the hoses on the connector on the firewall.

If I have to get at the actual hoses behind the connectors, or replace the piston/actuators that move these diverter doors, my research has convinced me I have to remove the whole dashboard. Anyone else can confirm this?

Thanks again!

 

[JP02XLT]

Good deal I would try to re-seat all the hose connections that you can reach sometimes they can leak a little, it may be fixed as it does not take a lot of vacuum to operate the valves. Mine did something very similar & I checked, cleaned & re-seated all the lines & connections & it has not had any problems for over 1 year now.


JP02XLT

 

[Dale_R]

Thanks - fixed mine too

Thanks to everyone who posted info on this topic. I bought my Ranger about 5 months ago (pre-owned). The vacuum lead that goes down to the vacuum accumulator / reservoir ("the ball") had come apart. Looks like someone had done a half-vast repair to it joining two ends of the 3/32 o.d. plastic tube with a short piece of vacuum hose that fit none-too-snugly. I'm going to use heat-shrink on it later for a more permanent fix. Idles better, too.

Best regards,
Dale