A/C only blows through defrost vents
 

I have a '97 Ranger with the 2.3 I-4. When I turn on the heat or a/c it only blows through the defrost vents,is this a vacuum line or stepper motor problem?

Sounds like the infamous "blend door" problem.

Have a look in the "Tech Info" thread atop this forum for a diagnosis & possible fix.

Let us know what you find.

I was JUST signing in tonight to post the exact same problem with my sister's 2001 Ranger 4.0 4x4.

Seems to be very similar symptoms. Heat and AC both work fine, but everything is just coming out of the defrost vent.

I just read the Ford Explorer Blend Door Fix article as well as doing lots of Google searching and lots of Youtube watching.

According to the HeaterTreater website, the symptoms are "The usual symptom is an inability to effectively control the temperature of the HVAC system."

This leads me to believe that it is probably not the blend door . . .

This truck can control the temperature just fine, but it is the direction of the flow that is not happening.

It will turn on and off, the air cools and heats, but will only come out of the defrost.

Any thoughts?

I think the defrost is the default position. thus when you lose vacuum it defaults to defrost. I have seen a a few threads on fixing this. I think "Big JIm" did one......cant remember if it was here or TRS.......i think there is a vacuum line that goes thru the firewall. look for a lose line

see if this helps

ac blows out the defroster ducts - Page 2 - The Ranger Station Forums

I like powersmoked's take on this if you've lost All functions on the HVAC system, as Defrost is the default mode, so loss of HVAC system vacuum belongs high on the suspect list.

CEL lit, any trouble codes, or fuel trim, or ping, miss, or idle problems????

Hey guys,
Thank you so much for your helpful suggestions!

It sounds like I've lost vacuum in my HVAC system.

No CEL, no funny running that I can tell (it is my sister's daily driver and she is not quite as observant about these things -- but if it was some drastic change I'm sure she would have noticed), doesn't appear to be any pinging.

This must be a small small vacuum leak, just enough to kick everything to defrost, but not enough to start messing with the engine.

It sounds like I should start with the canister. Is that in the same place for a 2001 Ranger?

I am not sure where the cannister is however you might as well ckeck the vacuum line on the heater control valve

I'd maybe start with where the vacuum line goes through the firewall, as thats a good rub point, or where it's exposed to extra heat, vibration, or passes close to any metal that could chafe it.

The connection point, where it stretches over it's vacuum fitting is a good stress spot too, so I agree the under hood vacuum canister connection which is exposed to more heat is a good suspect spot.

If it looks ok there, you could disconnect the vacuum line there, plug the canister fitting & apply vacuum to the HVAC disconnected vacuum line with a hand pump, start the engine & see if function returns.

If not, the problem is likely where the line goes trough the firewall, or in the cabin at the HVAC control as powersmoked suspects, or it's lines or actuators at the airbox.

If it works, then look to a problem with the vacuum canister line fitting, the canister itself, or the vacuum feed line to it.
With the hand vacuum pump you could test the canister for leaks too.

Seeing as how no other problems were reported I agree it sounds like a small leak, so it might be hard to find & will require careful inspection.

Let us know what you find.

SO, how is your trouble shoot going????

The above posts & links might help in sorting it out, let us know what you find.

Had the same problem on my 96 Ranger and found a small plastic vacuum line broken on the passenger side of my motor. I just added a small hose to reconnect it and everything started to work again.

just do like old women do. move your seat as far forward as possible and lean all the way forward all up on the steering wheel and the ac will blow right in the face! lol

My 99 Ford Ranger 3.0 4x4 Had the same problem. It turned out to be a broken vacuum line going to the passenger side wheel. The left and right side 4×4 wheel mechanisms works off the same vacuum reservoir as the A/C-defrost control.

There is a small vacuum check valve in line that keeps the system vacuum from fluctuating as the engine vacuum goes up and down. If the check valve fails, you only get default defrost.