I've owned 11 or 12 rangers since 1997 so I have always known about the AC compressor kicking off (cycling) when the truck is floored, but I have a different issue. When my truck is floored the vents will shift to defrost instead of continuing to blow out the dash. WTF?

It makes it get hot in the truck as I am driving if I am on the gas even a reasonable amount. The vents shift upwards to flow on the windshield instead of facing me. It makes it quite hot in the truck that way. When I let off the gas it puts the vents back on me.

What is the deal? What controls that? Anyone else have that issue?


EDIT::::

I have the exact same problem... unless you're a professional you just kind of have to play with the knobs until u find the one that cycles instead of only doing that. You're bound to have one setting that does that. Other than that, Ranger A/C systems are a mystery... If you want it fixed, go straight to a Ford dealer instead of a local shop or something. Local shops don't tend to know what they are doing when it comes to this problem.

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1996 Ranger XLT 4x4 V6 3.0
StreetGlow OPTX Neon Kit | JVC KD-S36 Head Unit | Pioneer TS-A6782R Speakers (Front and Rear) | UnderCover Tonneau | Goodyear Wrangler Tires | Self-Painted Front Grille and Emblem | Self-Painted Interior
Upcoming Mods: Reupholstered Leather Seats, LEDglow LED kits, & more (see avatar for details)
Might sound a bit "Ranger-racist" but I only REALLY like 93-97's.

you have a vacuum leak somewhere. when the interior system looses vacuum, it's natural place to go is defrost.

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Krylon Fusion is for Amateurs.

On some vehicles, that is the purpose of the vacuum reservoir. To keep vacuum to the a/c controls when at WOT. Have seen some guys have a failed reservoir and NOT replace it, they bypass it with vacuum line. This might be the cause. Check for leaking lines and a reservoir in good shape.

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From The Swamp, Lenny
2010 Ranger XLT, 2.3/M5
2012 Mustang V6/M6 Prem/Pony
2005 Corvette Z-51

Thanks for the insights. I'll just keep tracing the lines.

alot of rangers leak from the white/grey line that opens and closes the diaphragm on the heater hose. It gets hard over time and cracks.

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1999 Ford Ranger XLT 3.0 2WD
Black Single Cab with Flare bed...

It's more like a BIAS than a leak. A leak is at low vacuum, but our issue is at high rpm/vacuum so it is biasing (but it is doing it because of a leak so you are still right, just have to go about it backwards). I've looked it over and it goes as follows.

The black vacuum line is the main line. It starts out black in the cab at the switch and runs outside to an elbow joint just under the windshield washer fluid tank. From the elbow joint it runs to a bubble in the fender that looks like a filter/dryer then the vacuum line runs to just above the alternator to a coupler that turns it into a red vacuum line. This line and another line run through flex loom from just above the alternator down the side of the head, over the head at the rear, under the back of the intake, and around to finally plug into the side of the intake at the brake booster line going into the intake.

Ok, here's the last pictures. Where the black vacuum line comes around the elbow joint at the coolant tank it goes underneath and out into the fender to this bubble.

This is where I suspect our vacuum bias could be, but no idea at this point.

Anyone know what this is called?

This looks like a dryer/filter for the vacuum coming from the intake.

I took the elbow off the intake of the bubble and jumped it to the intake directly and the switch from dash vents to defrost vents is much quicker now so there is DEFINITELY a bias here as I thought. The weird thing is that with MORE vacuum it switches faster so I'm not on the right side of this problem. Everything here is good and I should be looking for the bias on the other side of the switch.





UPDATE......


PROBLEM LOCATED:

That basically leaves us the small area from the switch to the plug going into the blower housing. If the blower housing is mated up well you can likely blame a leak at the switch. How to see if it is the switch or not? Simply jump the red and black out as I did in my pictures above. If the problem goes away, your switch is leaking.

If the problem persists, check the plug mated to the blower housing. If neither fixes your issue, then blame the diaphragm inside the blower housing.

Remember, MORE vacuum on the intake side of the switch is a bad thing if there is a leak at the switch or blower housing (especially if the diaphragm is weak and leaking) as it will bias the vacuum to the intake side of the switch and cause the vents to go to defrost.

Anyone having this problem should try this first to diagnose if it is the switch or not and avoid everything I just went through.

I have this issue with a 98 xlt 4.0l, is it the same basic steps? or what? cause it's pissing me off! works fine around town, get on the highway and it switches back and forth..

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Joe.
'98 Ford Ranger XLT extend cab.

www.thefusionsolution.com

One1,
Thanks very much for your photo of the vac system. Because of them, I was able to trace a "defroster default" problem to a faulty Pulse Vac Hub selenoid assembly. Problem solved.
Thanks.
Dennis.

I noticed today that when I turn my truck off, I hear a sort of hissing sound coming from the pass side wheel well, then it stops.. I've never heard it before, as I don't use my ac that often, but today I used it and noticed the sound, could that be the ball thing?

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Joe.
'98 Ford Ranger XLT extend cab.

www.thefusionsolution.com

If you guys wanna skip doing all the hard work and just do a quick check to see if you have a faulty switch........ grab a piece of fuel tubing and run outside to the truck. Open the glovebox all the way and put the tubing in the place seen. It bypasses the switch, but connects the same ports as if the switch were there. You'll still have to turn to Max AC since the switch is partially electrical. If this fixes your problem, you have a leaking switch.

That's top and third on the right side where the red and black would be.

Ok, newb here, as far as 2.3 ranger goes. The gray vacuum line that archs over the heater hoses is cut off on my truck just at the top of the heater hoses. The rest of the line from the heater hoses toward the drivers side is missing, can anyone tell me or show a picture of where this line is run and connects to? I thank you in advance for your help!

speedfreak87 isn't that where your snorkel is? sure the hissing isn't the air filter sucking in air?

*edit* nevermind didn't read carefully you said when the truck is off my bad!