Compressor seizing

All compressors designed to run on compressor oil will fail in case of bad oil/refrigerant input to the compressor because the compressor will not be lubricated/cooled. For example, if an engine is run without oil or coolant, the engine will fail.

During normal compressor operation, the components are lubricated with a layer of oil that reduces friction and ensures heat dissipation. The compressor drives a mixture of oil and refrigerant through the air conditioning system. This mixture lubricates and cools the moving internal components of the compressor. The system cooler acts as a heat carrier and assists with component lubrication and heat dissipation from components. Poor lubrication leads to heat build-up and expansion of components. As a result of the expansion, the area around the components decreases/lifts and the oil film disappears. The loss of the oil layer causes metal to metal contact and seizure occurs.

For SDH compressors, common places of seizing are the central ball and piston rod sockets. Central ball seizure is an example of seizure that occurs when the compressor and/or the central ball do not have adequate lubrication and cooling. This failure often results in the central ball melting and welding to the fixed gears.*

In the case of SDV compressors, typically the stall area will be the balance ring.

* Compressors that have been found to have a manufacturing defect are covered by the Sanden warranty.

Description of air conditioner malfunctions

In the case of PX compressors, typically the seizing area will be the piston legs and swashplate.

In the case of TR compressors, typically the seizing region will be the center region of the scroll.

Stuck is caused by a lack of lubrication and cooling. This condition can be caused by:

Lack of coolant flow due to insufficient charging.
TXV congestion or failure.
Thermostat malfunction.
No air flow to the evaporator (blowing fan motor failure).
Lack of coolant and/or oil due to leaks or grease traps.
Lack of return oil due to too long cycle or insufficient charge in the system.
Blockage in the system due to pollution in the system.
Defective central ball or contacting gear surface.
Fluid slowdown due to incorrect system charging.
Filling the liquid refrigerant to the compressor (removes the oil film around the central ball when the compressor is connected).

Clutch slip

Clutch slip is a condition that occurs as a result of the armature plate not engaging or rotating in sync with the clutch rotor. Clutch slippage occurs under high torque conditions, very low voltage supply conditions, or as a result of clutch wear. When powered, the field coil becomes an electromagnet, magnetizing the clutch rotor and armature plate. Friction and magnetic attraction cause the armature plate and clutch rotor to lock together (clutch engagement) and rotate the compressor shaft.

Clutch slip specifically describes a condition that occurs when the armature plate cannot lock properly with the rotor. In this case, the armature will tend to drag (slip) towards the rotor surface. This drag (sliding) results in intense friction and heating. As the sliding continues, the heat causes deformation on the armature plate. In rubber fittings, clutch slippage can cause the rubber damper to melt, resulting in subsequent failure of the entire clutch mechanism.

Possible causes of clutch slippage and overheating:

Fluid migration to the crankcase when the A/C system is turned off.
Fluid deceleration – causes high shaft rotation torque. This prevents the armature plate from rotating and causes slippage.
Contamination on the friction surfaces reduces the friction coefficient on the two contacting surfaces and results in the sliding of the armature.
A low voltage in the field coil causes a decrease in the magnetic field strength of the field coil.
Excessive pressure in the system causes high shaft rotation torque. This prevents the armature plate from rotating and causes slippage.
Motor hardware faulty connection – can result in insufficient current being applied to the field coil.
Customer damage

Identifies compressor failure cases due to customer damage, incorrect installation, mismanagement, and/or incorrect system application.

Compressors are prone to damage when the air conditioning system fails. System failsafes such as Pressure Relief Valves (PRV), Thermal Protection Switches (TPS), and High/Low pressure shutoff are often used to reduce the chance of compressor damage under abnormal system conditions. These devices limit damage to air conditioner components by rendering the system inoperable when an extremely abnormal condition occurs.

When a returned compressor is analyzed for failure liability, an investigation is performed to determine whether the compressor has suffered use damage and/or improper installation. If the compressor has external indications or it is evident that it has been exposed to extreme conditions leading to the failure, the cause of the failure may be determined as customer damage.

Customer damage includes, but is not limited to:

Compressor ear bed damage is caused by an incorrect gap between the bracket and the ear bed. In some cases, the installation bushings need to be brought to the recommended position before installing the compressor.
Excessive torque applied to hose assemblies, which can result in stripping threads or breaking ports.
Faulty field service. Compressor failure can occur following incorrectly replaced or installed parts. A typical checklist includes:

–             Washing the air conditioner in case of oil contamination

–             Replacing the coolant and oil

–            Expansion valve replacement (if required)

–            All oil leaks must be repaired

Mechanical damage to the clutch, scratches, abrasions, dents, air gap replaced, lead wires removed, pinched, cut etc.
Mechanical damage to the compressor cylinder block.
Addition of unapproved chemicals that may cause system and/or compressor failure.
Improper packaging or transport of the compressor.
Improper modification to the compressor, e.g. painting, coating, polishing etc.
moisture contamination

Identifies the malfunction that may occur under conditions where moisture enters the air conditioning system.

The A/C compressor is designed to operate efficiently under certain controlled conditions. If contaminants enter the system, they reduce the efficiency, effectiveness and durability of the compressor.

In this context, humidity describes water in any structure (solid, liquid or gas). When moisture enters the air conditioner, it combines with the system’s refrigerant and becomes acidic.

can form a solution, which can corrode the internal compressor components. In this case, moisture does not directly cause compressor failure; failure is the result of a part weakening from rust and/or wear.

Moisture may form ice at the level of the expansion valve, causing unstable valve operation. As a result of this fault, liquid refrigerant reaches the compressor or a small amount of refrigerant/oil mixture reaches the compressor.

Moisture can also cause wear on internal parts such as the valve plate.

During normal compressor operation, the pistons compress the refrigerant gas in the cylinders. The presence of moisture in the system can cause the fluid to slow down. Fluid deceleration is when fluid is allowed to enter one or more cylinders.

Because the fluid is not compressible, compressor seals can become vulnerable when the pistons try to compress the fluid. Fluid deceleration can lead to permanent valve damage and reduced compressor efficiency.

Moisture contamination occurs when moisture is allowed to enter and remain in the air conditioning system. This condition can be caused by:

Improper vacuuming of the system.
Contaminated system components.
Contaminated refrigerant and/or oil.
Saturated or defective desiccant
Water permeability from hoses.
Exposing hooded hoses or any air conditioning components to air for extended periods of time.
Absence of suction/discharge flaps on the compressor
The desiccant should be replaced according to the air conditioning system manufacturer’s recommended service period.