Halderman: This sounds as if the A/C system is low on charge. Once the temperature increases, the pressure in the system increases enough for the low pressure switch to close, thereby allowing the compressor to work. The A/C system uses a low pressure switch that will only allow the compressor to operate when there is enough refrigerant in the system to move the oil through the system. Refrigerant oil (R134a system) does not mix with the refrigerant but instead uses the movement of the refrigerant through the system to lubricate the compressor.
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