What am I missing my ac blows only hot air? on 1997 Ford Explorer

I have a 1997 ford explorer ac compressor turns on mechanic put freon no leaks I can hear a pop when I turn the ac on like a door opening any idea what it can be?

Asked by for the 1997 Ford Explorer
Check the heater control valve under the hood. It's installed in the heater hose and it is supposed to cut off the hot coolant entering the HVAC system when A/C is selected!! IF it is not closing, A/C won't cool!!! Actuated by vacuum, common for vac. line to break.
1 more answer , 1 more comment
sounds like the temperature door motor is broke. located behind dash.
Thank you