Technician Handbook Air Conditioning for Collision Repair Compressor Is the Compressor operating normally? Operation • Observe any unusual compressor noises. Confirm that the electric fans immediately run at low speed. Magnetic Clutch If it has a Magnetic Clutch, is the clutch engaging? • Listen for the loud “click” that indicates the compressor clutch has engaged (energized). • Observe engine RPM. When the clutch engages there should be an additional load on the engine when the compressor engages. If RPM drops slightly and then increases this is an indication that the ECM is adjusting idle speed to compensate for the additional load.
DL Pulley If it is a Variable Capacity Compressor with a DL Pulley, is the Compressor Shaft Spinning with the pulley? Compressor Drive Belt Tension Is the Compressor Drive Belt tension correct? • At full load, the Compressor requires high drive torque to drive the belt. The Vehicle Repair Manual specifies the correct tension. • A Drive Belt Tension Gauge accurately measures the tension of multi-ribbed belts. Multi-ribbed belts do not tolerate stretch as much as V-belts. • Insufficient tension will result in belt slippage. • Excessive tension puts extreme loads on the front compressor shaft bearing. Do not over-tighten. • There are different tension specs for new versus used belts.
• Serpentine drive belts drives may have a scale on an automatic belt tensioner to indicate belt wear. If the arrow falls outside the scale area, replace the belt. Collision Repair & Refinish Training 27