1999 Jeep Cherokee sport/air vents do not blow out cold or hot while it is on

behind the center counsel between the floor and the heater housing is a part that is called the blend door actuator. these usually go bad and have to be replaced.

I have the same exact problem guy!!! its the switch that controls the climate control!!! you have to get a new switch for the climate control or you have to get a whole new panel which costs up to 800 but the switch is located behind the glove box and it move to tell the motor for it to be hot or cold air and its broken so thats the reason

the door isnt actuating for that vent
could be vaccum or the cable on it
Cheers Rob

Sounds to me like the blend door motor is starting to malfunction.

There is a flap that directs the air. the flap is controlled by a vacuum actuator. This is located inside the venting. The actuator is connected to little vacuum hoses that attach to the temperature control switch. Either the flap is stuck, or the actuator has gone bad.

The control valve that directs the flow of air is not working. You have to take the dash apart to get to it.

My 1999 limited does this. When i bought it off the guy he said that its because of some flap down by the passengers left foot. In mine the passenger air barely even blows because of this.

The center blend housing on the heater/a/c assembly is probably broken.

You may have clogged vents. Is their alot of junk on the floor tword the engine bay. This could be clogging the inlet to the vent.

Another issue could be internal a clog down inside of the dash vent systems or you could have vent door operating issues.

Yes go to you have to get the codes from your ATC controls first...Hold down the A/C button and the Recirculating button at the same time and while holding the two buttons turn you left temp. control up. It should give you codes if not then it will just read 00. Once you get those find out what they mean...20, 46,52,or 54 means you blend door(s) are stuck down and have to come up to allow heat to flow. Go to www.heatertreater.net and it will tell you how to replace it or in my case I just fixed it by putting a screw in it to hold the doors up....But hey i'm cheap so i like quick fixer uppers!!! Try that and lemme know if it works...