AC Blowing Hot Due to Low Refrigerant Levels

Low refrigerant is the most common cause for hot air. Confirm this by checking the AC compressor clutch while the engine is running; if the center of the compressor pulley does not spin, the system's low-pressure safety switch may be preventing engagement due to insufficient refrigerant. Use a manifold gauge set to measure the low-side pressure; values significantly below the manufacturer's specified range (typically 25-40 PSI depending on ambient temperature) confirm a low charge indicative of a leak.