AC in the back blowing hot air

[saquibrazak]

My AC in the front works good but when I turn on the fan in the back seats the outlets in the back blow hot air while the ones in the front blow cold air. I have all the knobs for temerature control set to cold. Any ideas anyone!!

Thanks
Saquib

[acemech129]

ive replaced alot of the thermal expansion valves for this problem on the ventures, also could be temp door actuator at back hvac unit.