heater/ac control

[rifle6]

Hey i have a tech question for you guys
my ac/heat just goes to defrost,
i removed the control box and the internal lever is attached to the slide selector. is this a vacuum issue or heat/ac controller box issue or neither.

i have found several on ebay but hesitate because i really don't know if thats it

sorry if this is a dumb question.

it is a 92 cherokee

 

[Bart]

Sounds like a vacuum issue to me. There is a vacuum hose kit you can buy from a dealer that replaces most of the lines over the engine.

 

[rifle6]

cool,
i will look into that.

does that kit come with a map? or would i refer to the chilton repair manual?

 

[Bart]

You may want to check your lines first, to see if you can find the crack in the lines. The ones that sit over the exhaust manifold are prone to get brittle first, but it could be any of them.

If you buy the kit it's pretty self explanitory where everything goes.

 

[78mitsu]

easy way to find them is to fire up the engine, use a propane torch (not lit) and run it over your vacuum lines you'll notice a defined difference in engine rpm, remove the gas app and do it again on that spot to verify mark it with a paint marker until you find them all.

 

[rifle6]

a vacumm leak could also affect other systems correct?
hubs?

that is a cool idea about the torch, key (not lit)!

 

[xjshorty21]

if you dont have a tourch you can use carb cleaner or starting fluid

 

[BrockSampson]

I would first check to see if you have vacuum at the vacuum reservoir. Its located behind the front bumper on the passenger side. Its a plastic ball about four inches in diameter. There will be two vacuum lines going to it. Pull them off and see if one of them has vacuum. While the engine is running, of course. Be careful when pulling them off. They get brittle when they get old, don't ask me how I know.

If there is vacuum there, look for a leak after the reservoir. If there is no vacuum, look for a leak before the reservoir. Refer to a repair manual for a "map".

If you have your control panel out still. While the engine is running, pull off the vacuum connector and see if one of the vacuum lines in the connector has vacuum. This will let you know if you have vacuum to the control unit.

 

[rifle6]

no.
it is put back together but while it was apart i did not notice a vacuum line going to it.
i guess i'll pull it out again tomorrow, and check the other things you mentioned as well.

thanks for the good info