Vents only blow hot air

[Just_Randy]

No matter where I put the temp control knob, it always blows hot. The AC works though.... It just started happening last winter out of no where. It was fine in the winter, but its 95+ now days. Anybody know what the problem could be?

Its a 1997 Ranger 3.0 4x4 5-speed

Thanks

 

[Big Jim M]

There is a thing that adjust the amount of heated air entering the system...It is called a "blend door". When the temp knob is moved the door opens or closes some..
The TEST is to start up with a cold engine, as in the morning, turn the AC to high and if it is cold and as the engine warms up it gets hotter and hotter..the BLEND DOOR is the culpret.
Blend doors in most modern vehicles are operated by a small lectric motor.. Available at the dealer..
Big Jim

 

[Just_Randy]

The AC always blow out cold air. I drove 15 miles in 95 degree temps with ice cold air blowing out all the way. The engine was overheated when I got there, but that's another topic.

However, when I have the AC off and just want outside ambient temp air to blow in, I get heated air instead. It seems the temp knob doesn't work at all.

 

[Big Jim M]

Ok then mess with the knob while the ac is on and see if it gets much hotter... The door may be in a partially open position and needs the new motor.. ONLY you will be able to tell what is going on there.
Big JIm

 

[Just_Randy]

Ok,,,, well,,, I wasn't sure if there was some "known" issue with them like the door switches and wipers and, etc, etc, etc.

Btw, where is the blend door? I'm going to tear into it now.

 

[Just_Randy]

It IS a known issue!

Here is the fix: http://www.blenddoorfix.netfirms.com/

But you have to drill the hole at an angle like this page shows: http://heatertreater.net/tech.html Drilling straight across didn't work too well for me.

The problem is the door only rotates maybe 45-50 degrees and the motor tries to turn it a full 90 degrees. So, the plastic shaft splits down the middle at the weakest spot.... the corners. That's why you always have to drill thru the corners. I guess occassionally the shaft breaks altogether. In that case you'll need a new door.

This really should be a sticky because everybody with a RBV will have this problem sooner or later. I found several posts on this problem just in the last few pages!

Btw, another fix would be to run a generic choke cable to the vacuum valve on the heater core water lines. You'd end up with full hot or full cold. No mix! But its better than hot all the time if your door is broke.

 

[jagar147]

Hot air

No matter where I put the temp control knob, it always blows hot. The AC works though.... It just started happening last winter out of no where. It was fine in the winter, but its 95+ now days. Anybody know what the problem could be?

Its a 1997 Ranger 3.0 4x4 5-speed

Thanks

Check the heater control valve.It's in line on the heater hoses,this is a vac controlled butterfly valve.If it is staying open you are pumping hot water to the heater all the time.There is a vac connection on the valve that goes to the vac motor mounted on the heater box behind the glove box.Disconnect this line at the valve with the engine running and see if it's pulling vac,if it is you have a bad valve,if not a broken line somewhere.

 

[Just_Randy]

I put a new one on already. The old one was leaking coolant. I know the new one is working because the AC blows out cold.

My problem was the blend door hinge was split down the middle. I suppose every ranger will have this problem eventually unless Ford fixed it somewhere after 1997. I fixed it with a nail like my last posts describes.