Apr 29, 2012, 9:16 AM
Post #1 of 1
WHAT TO DO WHEN REPAIRING AN AC SYSTEM DUE TO CATASTROPHIC COMPRESSOR FAILURE
Catastrophic compressor failure is when the internal components of the compressor come apart resulting in debris circulating through the system.
It's important to determine the reason why this occurred, so you can prevent the same thing from happening to your replacement compressor. Most failures occur from the compressor overheating, lack of oil circulating through the compressor, or some type of mechanical failure from worn or defective components inside the compressor. Just remember that lack of oil circulation could had occurred from a system that was running on a low refrigerant charge due to a leak. Just like doing an autopsy, sometimes it is a good idea to disassemble the compressor to see what kind of failure occurred and what may have caused it.
Before installing a replacement compressor there are some steps to take. If these steps are not performed, your new replacement compressor may end up with catastrophic compressor failure or will have a short service life.
Here are some steps to take:
* Replace the accumulator or reciever drier. Don't attempt to flush out the drier or accumulator. The drier cannot be flushed out due to its internal filter and desicant.
* Replace the condenser. Most condensers are parallel flow designs and the debris gets caught up in the small transfer tubes. No amount of flushing is going to remove all of the debris.
* Replace the orifice tube and/or expansion valve. This includes replacing expansion valves on rear air systems. Some orifice tubes are captured, so you'll have to replace the line or install an orifice tube kit if available.
* Replace the compressor manifold hoses if there is a muffler. The muffler is designed to dampen the pusations from the compressor as it pumps refrigerant through the system. Most mufflers have a screen that the debris can get caught up in.
* Flush the lines and the evaporator with an approved flushing chemical. Be sure to follow the chemical manufacture's directions. Also follow the vehicle manufacture's recommendations for flushing ac systems.
* If possible, install an inline filter and/or install a capture screen at the suction port of the compressor. This is extra insurance for your replacement compressor just incase there are fragments in the system that don't get removed.
* Follow the manufacture's procedures for reinstalling the components in the system, oil balancing, and evac and recharging. Oil balancing is important because you don't want all the system's oil in one component. The oil has to be distributed through the system to insure the compressor doesn't starve for oil when you turn the system on for the first time after repair. Be sure to install the recommended amount of oil in the system and to use the correct type and viscosity of oil recommended by the manufacture.
* Before turning on the system, rotate the drive plate on the compressor clutch 10 turns or more by hand. This ensures the cylinders or scrolls are purged of oil, so you don't have a hydro-locking condition (compressor slugging) when the compressor clutch is engaged.
* When the compressor is engaged, listen to the compressor for abnormal noises. If you hear knocking or grinding, shut the system off and determine the cause of the noise. This might be difficult to do on a noisy diesel engine. You don't want to have a defective compressor grenading and sending fragments through the system you just cleaned out.
* Monitor system pressures with your gauges. Be sure that your high side and low side pressures are in range for the ambient air temp. A higher than normal high side pressure is going to cause the compressor to run hot. If you have a higher than normal high side pressure, make sure you have good air flow through the condenser and your electric cooling fans and/or mechanical fan clutch are operating properly.
* Check for refrigerant leaks.
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(This post was edited by Discretesignals on Apr 29, 2012, 3:17 PM)