If your automobile’s air-conditioning system blows only warm air on hot days, it’s probably because it is low on refrigerant, and the most likely cause is a leak somewhere in the system.
Though many automobile owners think they need to recharge or “top off” their air-conditioning system with refrigerant on a regular basis, such as annually, that’s not the case. If the AC stops working (but the fan continues to blow warm air), a leak in a hose, connector or other part of the system is probably the culprit. During the winter, you may notice that the defroster isn’t clearing fogged up windows, and that also is a sign you have a leak. Most defrosters engage the air conditioning to dehumidify the air.