ACHRNEWS

Working on Small Capacity Systems

October 2, 2006
While troubleshooting small-capacity refrigeration systems, a technician should not be too quick to attach refrigerant gauges to a system. Small systems normally hold relatively small amounts of refrigerant. The process of attaching and removing a set of refrigeration gauges will release a small amount of refrigerant from the system. This loss could affect the operation of the system, especially if lengthy 6-foot hoses are used, or if a gauge manifold set is placed on and off several times.

Although at times it may be necessary to measure the system's pressures to discover the true cause of a problem, a technician should first attempt to analyze the system without the use of manifold gauges. This will help to eliminate the release of any refrigerant from the system, which perhaps could be the cause of an additional system problem.

There are several items a technician can check that will allow him to begin analyzing the system without the initial use of manifold gauges. First, he can check to see if all of the system's motors are operating such as the compressor, the condenser, and evaporator fan motors. If any of these motors are not in operation, then perhaps the problem is electrical in nature and reading of the system pressures is not necessary.

A technician can also check the condition of both the evaporator and condenser coils. Are they dirty? Is the airflow restricted in any way through them? In the case of the evaporator, does it have an excess of ice or frost on its coils?

Another initial observation a technician can make is to measure the system's discharge line temperature. On an operating system, it should be well above room ambient temperature. If the system's compressor is running and the discharge line temperature is at or only slightly above room temperature, then there is a problem with the flow of refrigerant throughout the system. At this point, it would be justified to attach a set of pressure gauges to further investigate the cause of the problem.

When it is necessary to actually measure the system's operational pressures, it is best to use a short gauge setup. This will diminish the amount of refrigerant released while reading the system's pressures. Although this setup does not allow refrigerant to be added or removed from a system, it does allow a technician to troubleshoot the system effectively without the loss of an excessive amount of refrigerant.

Some of these smaller refrigeration systems will not have access valves. Some type of saddle valve will need to be added to the system in order to check the pressures.

When adding a saddle valve, use a quality valve and make sure the tubing surface is relatively clean before attaching the valve. If installed improperly, these valves can leak refrigerant over time. If during the repair process the refrigerant needs to be recovered, it is normally best to remove the saddle valve and install a more permanent access valve, such as a Schrader valve.

These types of valve seem to lead to less future repair concerns.

Publication date: 10/02/2006