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.
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
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?
97 Ford Ranger, Ext. Cab, 2wd, V6, 4.0, 5spd,
90 Ford F250, 4x4, 7.3L Diesel, E4od
66 Ford F100, 2wd, all stock 352 V8 and 3spd, ugly as sin, but it runs!
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.
99 Ranger XLT 4dr 4x2 4.0L 5spd Auto 3.55L/S Payload Pkg2 Tow Pkg
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