depends on the vehicle, but most likely a leak in one of the lines. best idea would be to have the shop replace it, being that on some vehicles it can be -very- difficult.
Answering "Where do you add freon to your air conditioner in your ford ranger?"
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you use freon to cool your car and make the air conditioner work
FREON
it simply means you have to add freon to ur air conditioner....you can buy freon at any auto parts store.
The refrigerant (freon) in any air conditioner should last the life of the unit. If not, you have a leak.
If your air conditioner blows air but it's not cold air then you probably need freon in your air conditioner
FREON
It compresses the freon gas.
Freon for your cars air conditioner
It's out of freon or refrigerant.
Air conditioners manufactured between 1970 and 2010 use Freon as a coolant. Freon is scheduled to be phased out of usage by 2020. Newer air conditioner models use a different type of coolant.