Repairing refrigeration systems can be quite challenging at times, especially when a system has multiple problems. In these situations, it is always best to try to identify all of the system’s issues on the initial inspection, but this is not always possible. The first problem observed may not always be the only issue or the major issue. Having patience is definitely a plus during the troubleshooting process, as it is easy to rush to an early conclusion and overlook other problems. Having to explain that there are additional problems at an additional cost — after your initial discussion — can lead to an unhappy customer.
If the issue is electrical in nature, see if it is possible to safely bypass the component temporarily, as this will allow a technician to see if any other problems exist. For example, suppose a system has a defective temperature control and is undercharged. Bypassing the temperature control will let the system run and allow the technician to discover the undercharge. If the technician stopped the diagnosis after discovering the defective temperature control, he would have to go back to the customer and notify them of the additional issue and costs.
If the problem is refrigerant related, it is best to completely examine the system’s pressures and temperatures. Measure the system’s suction and discharge pressures, along with the evaporator’s superheat and the condenser’s subcooling values when possible. This will allow for a more thorough understanding of how the system is operating. Do not be a “one-gauge technician.”
It is not always possible to discover all of the system’s issues on the initial inspection. This is especially true when the system has a failed compressor. It is usually relatively easy to determine that the compressor is defective, but what caused it to fail? Is there another system problem that led to the failure? This is very likely, but you may not be able to discover the other problem(s) until the compressor is replaced.
There may be some additional testing you can conduct before replacing the compressor, such as measuring the refrigerant’s standing pressure. Is it at saturation? If not, why? If possible, verify the operation of the evaporator and condenser fans. Is the condenser coil extremely dirty? A visual inspection of the rest of the system might be helpful. If the system has a compressor contactor, are its contacts worn? Is there any electrical wiring that looks damaged?
On systems using a capillary tube metering device, it is possible for the capillary tube to also be restricted on a system with a failed compressor. Some technicians prefer to replace the capillary tube when replacing the compressor, to avoid discovering that it is restricted after changing the compressor. If you are unsure what caused the compressor to fail, it is best to let the customer know of the potential for additional repairs once the compressor has been replaced. Explain to them that you cannot determine if there are other issues present until you install a new compressor.
With a little extra effort upfront, it may be possible to discover some of these additional issues – not every time — but you should always attempt to be thorough in your initial inspection.