Category: A/C compressor clutch coil

ac compressor oil

Car A/C compressor cycling on and off

The car a/c compressor cycles on and off according to the air conditioning system temperature and pressure. Normal on and off cycling happens at a manufacturer predetermined a/c system temperature and pressure. Car ac compressor cycling is one of the logics used by car manufacturer to protect the car a/c system by preventing excessive high pressure or excessive low temperature.

Rapidly car ac compressor cycling on and off.

Rapidly car a/c compressor cycling on and off could indicate a problem in the car air conditioning system. As a safety measure the compressor cycling clutch devices interrupt power to the compressor clutch coil to avoid damage to the compressor, evaporator coil freezing up or ac hoses damage. Any car ac compressor operation under extreme parameters of temperature and pressure will affect the  compressor oil quality and circulation back to the compressor and could exceed the design work pressure and temperature for the ac components in the vehicle.

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Air conditioning.A/c compressor clutch

What causes AC compressor clutch failure?


With a large refrigerant undercharge, oil is pumped out from the compressor and becomes trapped in the evaporator or other ac components of the system and is unable to properly return to the hvac compressor. The amount of oil in the compressor can get down to dangerously low levels creating excessive heat and, in most cases, leading to failure of the unit. Some Air conditioning tests has shown that with an undercharged ac system, the oil amount in the compressor was reduced by over 57%.

  1. Poor ac performance 
  2. Growling noise
  3. Whistling noise
  4. Grinding noise
  5. Squealing noise
  6. Rattling noise
  7. Banging noise
  8. Knocking noise

What causes AC compressor clutch failure?

All electro-magnetic clutches operate on the same principle of using an electrical current passing through a coil of wire to create a magnetic field capable of creating an action. These are some of the reasons why an ac compressor clutch may get damaged:

  • A/C compressor over cycling.
  • Excessive high compressor temperature due to air conditioning system contamination.
  • Cooling system underperformance affecting a/c operation.
  • Drive belt slipping on a/c compressor pulley creating excessive high heat load.
  • Slipping clutch pressure plate due to out of specs compressor clutch gap.
  • Shorts to power or ground on the ac compressor clutch coil circuit.
  • A/C compressor clutch relay inoperative or shorted.

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