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climate control vents, 1990 jeep

Black1990jeep

NAXJA Forum User
Location
california
On my 1990 jeep, the A.C. was working fine when suddenly we noted no more cold air blowing except thru the defogger vents regardless of vent lever handle position. then noted that the cold air did blow strong thru the dash vents when throttle was let off at speed, i.e. at increased engine vacuum the vents did work. when throttle was opened and accelerating, the vents shut again, i.e. poor vacuum level.

thus it appear there is an issue with the vacuum operated vents. on first glance, no signs of busted hoses or vacuum canister.

wondering if there is a common failure point(s) where I should check first?

thanks!
 
OK, symptoms indicate low vacuum, as low vacuum cause defroster vent to close and opposite on dash vent which closes at low vacuum.

with hand pump could not pull vacuum on the vacuum supply hose on the manifold.

looked at recirc. air valve vacuum motor, which is in passenger footwell, and saw vacuum hose to the recirc. air vacuum motor had come off the barb fitting! Installed the hose and all is well now.

Evidently there is supposed to be a kick panel covering the vacuum motor, something that is missing on my XJ. Hose likely bumped off the fitting by passengers foot. Need to visit the wrecker to obtain a kick panel.
 
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