Externally Vs. Internally Controlled Compressors: How to Tell the Difference
Looking for a compressor for a late model vehicle and see two compatible options with the same engine capacity? Typically, the key difference is whether the compressor is controlled externally or internally. Use the following steps to determine the correct compressor:
- Does the vehicle have climate control or manual controls? Usually, but not always the case, if your vehicle’s compressor has climate control, you have an externally controlled compressor. Manual controls usually mean you have an internally controlled compressor.
- Look at the compressor in the vehicle. This is the most accurate way to determine the compressor type. Does the compressor have wires going to the rear body of the compressor? Externally controlled compressors will have wires coming out of the rear of the compressor. These wires communicate information from the ECU (Engine Control Unit) to properly adjust the angle of the swash plate. Internally controlled compressors rely on the pressure in the crankcase of the compressor.