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  Misc. Information

 TechConnect from ACDelco®         January/February 2005 Volume 12, No.1 - Back to Index Page

Over the past several years, ACDelco® has reviewed, inspected and reinstalled hundreds of air conditioning compressors returned under warranty. The failure of these compressors can be grouped into four basic modes: lubrication, refrigerant, debris and product defects.

The exact percentage of each mode varies slightly among models and manufacturers, but in general, about 1/3 of the compressors failed from lubrication problems, approximately 1/3 failed from refrigeration  problems, slightly less than 1/3 failed from assorted internal debris, and the 1–2% balance were associated with various manufacturing defects.


Be assured that ACDelco® has been actively working with the various manufacturers to incorporate quality and reliability enhancements into the compressors to reduce and eliminate the manufacturing defects. However, the majority of warranty returns — many of them repeat compressor replacements — can be attributed to factors all under the control of the installer.

In a medical emergency, a triage is often performed at the hospital to quickly and accurately define the problem and provide proper follow-up care. A similar situation should take place when a customer

arrives with an A/C refrigeration condition at a service center.
Procedures enacted here will pay immediate as well as long term benefits. These A/C triage procedures would include:

1. Quickly and accurately assess and confirm the condition
2. Find and stop refrigerant loss
3. Clean and contain internal debris and contaminants
4. Replace missing fluids
5. Provide professional follow-up

Assess and Confirm the Condition

When inspecting many replaced compressors, they are deemed NTF (No Trouble Found) because the initial review was inadequate. It failed to verify the root cause. A quick visual prevents needless replacement caused by low charge, Diagnostic Trouble Codes (DTC), electrical connections, loose fasteners, etc. Quick checks for proper charge levels and purity as well as electrical confirmation of clutch engagement will significantly reduce the number of times a good compressor is replaced.

Stop Refrigerant Loss (or Stop the Bleeding)

Refrigerant is vital to the short and long term operation of a compressor. It is the refrigerant that is  responsible for transporting the lubricant throughout the system. Low or no refrigerant will not provide adequate compressor lubrication. As mentioned earlier, low refrigerant and poor lubrication account for nearly two-thirds of the replacement compressor warranty returns. Replacing a compressor WILL NOT ensure that the refrigerant leak is fixed. It only takes a few minutes to check with both a UV light and a quality electronic leak detector to confirm that there are NO OTHER leaks. Vacuum and pressure leak checking will not locate leaks that will take out a compressor in one-to-three months. The loss of one ounce per month may be a 20% system loss on some vehicles during this period. This low charge will cause compressor noise, an irate customer and a NTF compressor return.

Clean and Contain Internal Debris and Contaminants

Prior to as well as after compressor failure, debris particles from the failure flow throughout the refrigerant system — in BOTH directions. Although a majority of debris travels downstream from the compressor, upon shut down and equalization of remaining refrigerant, the flow reverses and does flow from the compressor suction port toward the suction muffler, hose, A/D and evaporator. These particles imbed themselves in various internal components and cannot be 100% flushed out. They will find their way back into the replacement compressor.

In addition to debris, the refrigerant lubrication may be burnt or contaminated from improper sealant or refrigerant. As with the medical field, successful treatment requires cleaning the damaged area and providing treatment, which will prevent future infection.

The first step is to inspect and clean or replace the existing system debris containment components. These include the orifice tube, TXV screen(s), A/D or R/D and any inline filter.

The A/D or R/D cannot be service cleaned. The general rule of thumb for A/D or R/D replacement is:

• A/D or R/D age over three years
• Sealant inclusion within the system
• Significant debris found within the system after compressor failure In addition to reviewing the existing OEM filtration devices, it is important to remember that the OEM system was installed with a certified clean system. Once a component fails, the only way to ensure the system is completely, 100% clean is by replacing all A/C components, which is rather impractical. Therefore, it is critical for the service technician to provide protective devices not originally included in the OEM system (they were not needed under factory new conditions) to prolong service repair life. ACDelco recommends the use of a suction screen on all compressor replacements where the replacement compressor does not come with an internal suction screen (for example, A-6, V-5 and V-7 models).

The installation of the low-cost suction screen provides additional protection to the precision replacement compressor installed in a compromised environment.

In addition to the suction screen, ACDelco has redesigned the in-line filter employed to prevent rear TXV’s and orifice tubes from premature plugging. This filter offers the additional filter debris capacity to maintain system integrity. This newly redesigned in-line filter is a universal one-size-fits-all part that has a significantly increased debris containment screen and a technician-friendly leak-free installation design. In addition, it can be employed as a line splice for repairing leaks on A/C lines to rear systems.

Flushing is mentioned often in the aftermarket as the panacea to system contamination. Flushing will remove lubricant from the system and will remove some, but not all, of the debris within the system. However, flushing is an expensive process.

Since contamination is generally spread throughout the system after compressor failure, not to flush the entire system would be similar to changing just the shirt of a small child who had fallen in the mud. The kid’s still not clean and neither is the system without flushing.

In addition, all OEM’s except Ford insist on refrigerant flushing only if flushing is to take place. Ford allows solvent flushing, but only using an endorsed flushing material and with the approved flushing equipment. As mentioned previously, flushing does not 100% guarantee particle removal, so preventive suction and line filters are highly recommended to capture those elusive remaining particles. The aftermarket use of sealants has provided the service industry a repair dilemma. There are currently numerous chemical sealants employed in the automotive A/C service industry. No OEM currently endorses the use of sealants. However, given the thousands of sales made to the do-it-yourselfer and repair shops, they will be in vehicles you service.

Removal is dependent upon the amount and type of sealant employed. There currently is no method for 100% removal of sealants (short of total component replacement). A/D or R/D replacement will greatly reduce system sealant quantities but not completely remove it from the system. In addition, the refrigerant and associated lubricant removed by recovery equipment assists to minimize the level of total system contamination. Of importance to technicians with this recovery is protection of their expensive recovery equipment from sealant. There are no tools to identify all the sealants employed in the automotive aftermarket. Therefore, the use of a seal-ant protection device or seal-ant detector prior to running the recovery equipment is a worthwhile investment.
Replace Missing Fluids

There are two important fluids that must be replaced in proper quantity and quality. These are lubricant and refrigerant. The compressor manufacturer must approve the lubricant. The use of ACDelco lubricant assures warranty coverage and OEM specifications adherence. No OEM automotive compressor manufacturer endorses the use of esters. Their use will void the warranty from ACDelco.

The second lubrication issue is to ensure an adequate amount. A lubrication replacement balance guide is included with re-placement compressors. Failure to heed these guidelines to lubrication replacement after component replacement or flush can and will cause premature failure and replacement.

Finally, refrigerant quality and quantity is critical in today’s automotive A/C system. Today’s systems will lose performance and reliability as well as create noise if the charge is not kept within the manufacturer’s specification.

The use of 12 ounce cans will not provide this accuracy. Current charge equipment, when maintained, will provide charges within the +/- 1 ounce tolerance often required. In addition, if a refrigerant identifier is not

employed after charging, there is no way to ensure that excessive air or alternate refrigerants are present. After charging, both of these contaminants will cause noise and premature compressor failure.

Provide Professional Follow-up

The term professional follow-up means more then being paid to repair an A/C system. It means the ability to provide the customer with qualified diagnostics and quality OEM replacement parts and service materials. Rechecking the details prior to final customer release is very important. The reinspection of the entire system for leaks, functional testing with a thermometer, checking gauge pressures and performing purity tests will ensure customer satisfaction.

Remember, quality parts also require quality installation and attention to detail.



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