If you do not recharge a car's AC system that is low on refrigerant, the air from the vents may remain warm or feel only slightly cool. The AC system may run longer, struggle in hot weather, or stop cooling at idle. Low refrigerant can also reduce lubrication in the AC system because refrigerant helps carry oil through key components. Over time, this can put extra stress on the compressor, which is one of the most expensive AC parts to replace. Some vehicles may disable the compressor when pressure is too low to prevent damage. Ignoring the issue can also allow a leak to get worse. A proper AC inspection and recharge can protect the system and restore comfort.