A/c warm air

My a/c is blowing out slighty warm air...how do i check it?? thanks

Check the refrigerant charge at the low pressure port and make sure it corresponds to the ambient temperature. The low port is located at the firewall. You can get inexpensive kits with a gauge and the R134a refrigerant at most auto parts stores unless it is illegal in your state. These kits work fine unless you have other major A/C problems.