1998 Cherokee. Air conditioning will work great. Blows real cold air, then suddenly air will turn warm. Then just as suddenly it will turn cold again. Any help will be appreciated.

 

Sounds like a it could be a blend door problem.

 

Sounds like the evaporator icing up and when the low pressure switch shuts down the compressor the ice melts; when the system pressure returns to normal and the LPS fires up the compressor again, then everybody is happy again.......until it ices up again....

OP - Is it real humid at your local?

 

Yes. Real humid.

 

^^ This sounds like your problem^^
Next time it stops blowing cold pop the hood and check out the AC system. I bet that you will have a few parts frozen over.

 

Icing up generally will also caused reduced airflow thru the vents. This sounds more like intermittent clutch engagement (need to reshim) or potential problem with pressure switches.

Easiest way to diagnose. Next time it happens, pop the good and look for frosted/frozen A/C lines and make sure the compressor clutch is engaged/turning the compressor.

 

How do we fix the icing up issue?

 

I too have this problem. to be honest I have not check for frosted hoses, etc. but I think mine is the shim issue. When my jeep gets warm when warm out i.e. in standstill traffic and the ac is on it will fade and start to blow warm. But it could be 100 degrees outside and I'm traveling down the highway with no traffic AC will blow cold no problem. I've read that when it heats up enough things expand and the magnet can't engage the clutch anymore. This is solved by removing a shim allegedly?

As soon as I get moving and the temp goes down a bit and I turn the AC back on it's fine again.

edit: lol just realized this an ancient thread....

 

https://www.cherokeeforum.com/f2/199...eze-up-262959/