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Interesting problems 89 mid-sized wagoneer lmtd.

andromeda2015

NAXJA Forum User
To me this sounds like a vacuum leak problem, but I have no clue where to check and what other problems could be associated with this, so hopefully you guys can help me out!

Under about 50 mph:

vent- works fine when put on cold or hot

defrost- when put on cold, lots of air, but when on heat very little

a/c- works fine on cold or heat

heat- has little coming out of defrost vent, also makes internal
motor type noise from defrost vents




above about 50 mph:

vent- cuts in and out of vents and defrost

a/c- cuts in and out of vents and defrost

defrost- has little to none coming out

heat- has little coming out of defrost vent, also makes internal
motor type noise from defrost vents



I've checked in a manual and mine doesn't have much troubleshooting for the A/C and ventilation systems.
 
Yep it is a vacuum leak somewhere. My 88 did the same thing when it had the vacuum/swiss cheese system. Chased down all the leaks, and no more vent suddenly changing over from heat to defrost or back.
 
start with the vacuum bottle in the front bumper and the lines that lead to it, specially where they run under the batterytray..
mike
 
Best place to look for that leak is either going to be at the bottle itself or under the battery. I'd actually recommend looking there first but the bottle is a quick check, the battery requires tools...
 
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