I have a 93 Grand Cherokee, last summer the air worked fine, but the heat didn't work in the winter. Now my air won't blow cold. Pump, compressor and blower all work fine.
Any ideas on what this could be?

 

Sounds like it could be a problem with the blend doors.
And Welcome to CF!
Dan

 

Thank you for the welcome.
About these blend doors, can you elaborate?

 

They mix the inside & outside, heated & cooled air to achieve the desired temperature. They are prone to becoming loose on the shafts they're mounted on then can't properly regulate the temperature. Sometimes getting heat or cold air when unwanted.

 

Okay, so what is the fix?

 

"If" that's your problem you'd need to disassemble your HVAC box and replace the blend doors. It might just be the vacuum motors that drive the doors. You need to get under there while someone is switching the controls and see if you can tell if the vacuum motors are working first. JMO

 

To give you an idea, here's a link showing the same thing for the WJ "99- ;04 Grand Cherokee. http://www.wjjeeps.com/hvac_sub_assembly.htm

 

Thank you so much for the information. Doesn't look like something I would want to tackle myself.

 

Okay, doors and compressor appear to be functioning just fine. When in idle the heat will work great.
The air compressor cycles.
Do you think that there may be a chance that it is the thermostat? Our gauge on the dash doesn't adjust at all until in idle for at least 10 mins, it used to work just fine. When put back into drive the temperature drops back down.

 

It's possible.

 

Okay, here goes...I have a 93 Jeep Grand Cherokee, the A/c will not blow cold air, the lines get cold, the compressor cycles. Everything seems to be in proper working order. Freon is full....any ideas? Please help!

 

Okay, well it must be the temperature control isn't functioning when you try to change to cold when you use the AC. It must be in the cold position or you will get hot/warm air from the outlets even with the AC on.

 

I have air blowing out, it is not as warm as it was but is still pretty warm.. But the air does blow.
Any ideas now?

 

Okay, I think we fixed it. the compressor sensor is apparently blown. We bypassed it and it is much cooler now. Now to figure out how to get it cold. Thanks for your help.

 

I'm trying to say that some vehicles, I don't know if yours does, has a heater control valve. When the temp. control **** or temp. setting is put on cold or a colder temp. setting, it stops the flow of hot coolant to the heater core. Since the heater core & the AC evap coil are in the HVAC box next to each other, this is beneficial when using the AC, as it doesn't have to overcome the heat that would be in the box if hot coolant were allowed to flow through it while the AC was on.