[header] How to fix your car's air conditioner [title] Start the vehicle and turn on the air conditioner. [step] Use the key to start the car and turn the air conditioner on high. Feel the air coming out of the air conditioner and assess how warm, cool, or cold it is. 
If the air is warm to cool, but not cold as it should be, there may be an issue with air flow. [substeps] Check to see if the cooling fans on your radiator are running.