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724-746-5500 | blackbox.com
Page 120
724-746-5500 | blackbox.com
Chapter 5: Maintenance
5.3.2.3 Refrigerant Piping
When replacing components within the cabinet of the unit, the following consumable materials are recommended: When brazing
copper-to-copper connections (piping liquid line or suction line), use a phosphorus copper brazing alloy with 15% silver.
Use general-purpose silver brazing alloy with 45% silver for copper-to-brass or copper-to steel. For liquid line repairs at the drier,
strainer, sight glass, or expansion valve, use a 95% tin to 5% antimony solder with flux.
When component replacement is complete, remove all traces of flux. After any repair, pressure check the system to ensure there
are no leaks prior to recharging the system.
5.3.3 Refrigeration System Repairs
5.3.3.1 Compressor Failure
The compressor is the most important component of the air conditioner. Numerous safety devices are provided to protect the
compressor from failing.
If a compressor failure occurs, determine whether it is an electrical or a mechanical failure. An electrical failure will be indicated by
the distinct pungent odor once the system has been opened. If a burnout has occurred, the oil will be black and acidic. A
mechanical failure will have no burned odor and the motor will attempt to run; an abnormal or excessive noise may be present.
An analysis of the oil is the only way to determine the proper procedure for cleaning the refrigerant system. Acid test kits are
available from several manufacturers for measuring the acid level in the oil. These are capable of making accurate acid
measurements, but if they are not available, a check of the oil by sight and smell can give a quick indication if contamination
remains in the system.
CAUTION
Avoid touching or contacting the gas and oil with exposed skin. Severe burns will result. Use long rubber gloves in handling
contaminated parts.
All electrical connections should be checked to ensure they are tight and properly made. Check all circuit breakers, contactors,
and wiring. The contactors should be examined and replaced if contacts are worn or pitted.
If there is acid in the oil, there has been an electrical failure that has caused the compressor motor to burn out. The acid diffuses
throughout the refrigeration system and must be removed by using a burnout filter kit before a new compressor is placed in
service. Not only must the compressor be replaced, but also the entire refrigeration circuit must be cleaned of the harmful
contaminants left by the burnout. See Section 5.3.3.3 (Burn-Out/Acidic Cleanup) for the proper procedure.
If there is no acid in the oil, there has been a mechanical failure. See Section 5.3.3.2 (Standard Cleanout) for the proper cleaning
procedure.
CAUTION
Damage to a replacement compressor caused by improper system cleaning constitutes abuse under the terms of the warranty.
This will VOID THE COMPRESSOR WARRANTY. Always consult Black Box Technical Support before replacing the compressor.
CAUTION
POE oil is used in systems with R410A refrigerant. If a replacement compressor is provided, ensure that it is filled with POE oil
before installing.
NOTE: Cleaning operations must be performed by a journeyman refrigeration mechanic or air-conditioning technician.