A/C blows hot air only??

Hi all,I did a search for A/C but didnt find a similar problem as the one my roomate has.
he owns a 98 Cherokee Limited that when the A/C is on only blows hot air
we tried a gauge on it and it seems too be at the proper level also the line coming from the firewall is ice cold but nothing but heat coming from the vents??
any thoughts would be greatly appreciated.

Hi all,I did a search for A/C but didnt find a similar problem as the one my roomate has.
he owns a 98 Cherokee Limited that when the A/C is on only blows hot air
we tried a gauge on it and it seems too be at the proper level also the line coming from the firewall is ice cold but nothing but heat coming from the vents??
any thoughts would be greatly appreciated.
I would guess that either:
1 - the doors that control the air flow through the heater / AC assembly (under the dash) are not moving properly or
2 - The heater control valve is not working or
3 - Some combination of the above.

I believe most of the controls for the AC & heat are vacuum controlled. I would check for leaks.

Also, here is a link to autozone that has some drawings around the systems. They appear to be the same as the ones I have in my Haynes manual for 84-93. You might want to explore a little more on that site.

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/15/2b/11/0900823d80152b11.jsp

Please let us know what you find.

Take Care ,

I have a 2000 that also blows hot air. It started as an itermitent problem then evetualy the A/C failed to blow cold at all. When I got the jeep I would hear the A/C pump come on then turn off frequently. This cycle happend with the A/C on or off. It is now to the point that I no longer hear the A/C pump come on or off. I had a local garage check out the problem. It appears that the clutch on the A/C unit has failed (electrical check showed that the clutch is reciving power to the actuator, and system pressure in within normal range). It is cheaper to replace the A/C unit than just replace the clutch. I have also been informed that the A/C is supposed to cycle as a feature of the defrost cycle, something about removing humidity in the cabin (sounds googfy to me).

the a/c cycles with the defrost so that the system will get turned on in the winter. The a/c should run for at least 30 minutes a month wether cold or hot and most people would not turn it on in the winter , fall and spring and summer would come and the a/c wouldn't work so they made the a/c cycle everytime the defrost comes on.