Heater/AC vent problem

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Sep 6, 2006 | 01:41 PM

Boxer347

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Heater/AC vent problem

I just bought a 1992 F150 and am having a bit of trouble with the vent position. The A/C works great but when accelerating the air moves from the dash vents to the defrost vents. When coming to a stop sign, it returns to the dash vents. It does this with the AC or heater on. Has anyone had this problem before??

Sep 6, 2006 | 03:13 PM

tjc transport

i ain't rite

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From: Marlboro Mental Hospital.

you have a broken vacuum line from the vacuum t to the heater controls. it is usually in the engine compartment where it breaks.

Sep 6, 2006 | 03:38 PM

albung

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From: youngstown ohio

check that on pass side near antenna theres a valve with vac running to it make sure it hooked to lever as mine came off and was moving when i started out or stopped

Sep 6, 2006 | 08:53 PM

wrenchturner

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From: shelocta, pa

Sounds like a vacume problem check your hoses.

Sep 7, 2006 | 06:58 AM

Old_Paint

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Quote:

Originally Posted by Boxer347

There are a couple check valves in the lines for the vacuum reservoir and ventilation controls in the line between the plenum the reservoir inside the cab. If either of these has failed, or is missing, then you'll also get exactly what you're talking about. Check the reservoir as well. Unless I'm badly mistaken, there's normally a check-valve in the fitting where the vacuum source connects as well. That's exactly what these reservoirs are for, to prevent vacuum loss to things that should hold position for the times we need WOT.