Mechanics

AIR CONDITIONER

2002 Ford Explorer • 160,000 miles

I have a 2002 ford explorer. 4.0L engine. When I turn on the truck and the a/c it works fine on settings( front vent, defrost, feet vents etc). I do city driving and everything works fine it blows cold air. But when I get into the freeway n I start to accelerate it switches the settings by itself ( the air stops blowing on the front vents and it switches to the defrost setting) this happens mostly when accelerating and it after a min or two it switches back to the front vent? This only happens on freeway driving. Also when I put the car in cruise control a/c works fine. Please help?
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Azamora1524
July 5, 2013.



I would check and make sure the mode door diaphram holds vacuum and isn't leaking?

Saturntech9
Jul 5, 2013.
Where is the mode door diaphragm and how do I check for vacuum and or leaking? Thank you.

Tiny
Azamora1524
Jul 6, 2013.
It will be up under your dash in the center with the engine running move the mode knob to the different positions and you will see it move so you know which one it is. Also you will need a hand vacuum pump to pull a vacuum on it to see if it leaks. You can also use it too measure vacuum. You hook it up to the nipple of the mode actuator pump it up to about 20 and see if it holds. Auto zone might rent one.

Saturntech9
Jul 6, 2013.
Hi I just did the vacuum pump test and the actuator holds vacuum. What would be the next step? Also I notice that after having the ac on and I turn the ignition me I can hear a hissing sound on the engine compartment and itS just after I turn the ignition off after having the ac running. When ac is off n I turn off the car I dont hear the hissing sound in the engine compartment. The hissing sound is like f you are taking the air out of a tire.

Tiny
Azamora1524
Jul 7, 2013.
Sounds like you may have a leak from the vacuum source to the actuator that at higher rpms with the engine under a load can't over come the vacuum leak.

Saturntech9
Jul 7, 2013.
Where is the vacuum source on this particular vehicles and what can I do to fix it or do I have to take it to a shop. Also will this get worse as time passes? And will this affect anything else?

Tiny
Azamora1524
Jul 7, 2013.
Do you have auto climate control or manual climate control?I am trying to find info on vacuum sources.

Saturntech9
Jul 7, 2013.
Manual climate control

Tiny
Azamora1524
Jul 7, 2013.
The hose goes from the ac controls down to the mode actuator. Also there is a vacuum check valve on that line that only allows vacuum to go one way to the mode actuator. Pull a vacuum on the hose from where it connects to the ac controls. Unplug it from the ac controls leave it hooked to the mode actuator. Then pull a vacuum on the hose and see how it holds vacuum?

Saturntech9
Jul 7, 2013.
Hi I have resolved the issue. I looked under the hood and found a hose that was loose and I put it back together and everything worked. Attached is the picture of the hose that was disconected

Tiny
Azamora1524
Jul 8, 2013.
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