I just recently bought a 97 jeep cherokee and the front defroster vent doesnt work all the time. It will work for about a minute or two and then a loud thud and the defroster vent closes and i cant see out my windshield. Anybody know the cause of this or a way to fix it. Also, i cna not control wether it goes to front vents or defroster it is defroster or nothin.

 

The lever from the defrost actuator to the defrost door is probably broken. The thud you hear is the defrost door slamming shut from the air pressure from the blower fan. You used to be able to get the lever separately, but now the part supercedes to a revised HVAC housing. The entire instrument panel needs to be removed from the vehicle to replace it.

 

where can i find a replacement hvac housing?

 

try J Parts, they have pretty much everything for Jeep and Dodge replacement parts.

 

Is it possible that there is a vacuum leak somewhere that would cause this problem?

 

Don't think it would be a vaccuum leak, because 89Daytona says it works for a short period. If it was vaccuum leak, it would either only work in defrost or the defrost wouldn't work at all in this case.

 

Well, on my jeep i think it is a vacuum leack somewhere between the point it comes into the interior compartmen and where it meets the defroster thing. Because i was driving it the other night and after awhile it will come back on for a few seconds and then it will shut again. Also when you turn it off it makes a squeaking noise. Any ideas on how to check if its a leak or a mechanical failure?

 

You can use one of those hand held vacuum pumps (around $20 at auto parts stores) to apply vacuum to the line, if it holds vacuum the line doesn't have a leak.