defrost uses compressor to make cold (dry) air

i agree you need to get this thing fixed ASAP unless you want to get into buying a compressor too. The shop needs to recover all old refrigerant and oil. And add oil and refrigerant when the repair is completed

 

Even more than defrost. On my 09, and I believe on my 04 and 07, the compressor kicks in anytime the air is routed through the defrost or dash vent positions. Only time it does not kick in is with floor vent only is selected.