One contaminant that must be removed from a refrigeration system before refrigerant can be added is water vapor. If water vapor is left trapped in a system, it can lead to some serious problems. Technicians will typically reduce the system’s pressure to about 500 microns to remove this water vapor.

There are several ways we can get answers to our questions. The easiest way is to just ask someone who has more experience with the system or component. However, if an answer does not make sense or is unclear, we should not just simply accept it as fact, but should ask it again or ask “why.”

Thermistors are one type of temperature sensor used on electronic control systems. Technicians servicing these control systems need to be able to test the operation and accuracy of these sensors. A defective thermistor can easily cause a controller to not operate correctly.

An oil separator is an accessory used on some larger refrigeration systems to help limit the amount of oil in circulation. It is typically used on low temperature applications where the refrigerant’s mass flow rate is low. But it could be used on any system.

Troubleshooting a refrigeration system is all about gathering information and using that information to determine the cause of a problem. Technicians are always measuring voltages, amperages, pressures, and various temperatures to help them find a problem. Besides these important measurements, there are other pieces of information that can assist a technician.

One of the common problems found while troubleshooting reciprocating compressors is that they simply fail to start. This could be the result of many different causes, both electrical and mechanical. One common mechanical cause is a stuck piston. Mechanically the piston cannot overcome an internal resistance to move.

Many low and medium temperature single-phase compressors require some type of external relay to assist in the starting of its motor. The purpose of this relay is to remove the motor’s start winding, start capacitor, or both, from the circuit once the motor is running.

In a properly operating system, the refrigerant will be in a superheated state from the last section of the evaporator to the first section of the condenser. Technicians can measure the superheat condition anywhere along this path. One common location is at the outlet of the evaporator.

A service technician should not only fix the problem but also, to the best of his ability, ensure the system operates reliably. This means once a technician identifies the system problem, he should try to discover why the failure occurred and what can be done to prevent it from happening again.

Being able to efficiently interpret ladder (line) diagrams is an important part of electrically troubleshooting many HVACR systems. These diagrams are drawn in such a format that it is quite easy to understand the electrical configuration of the system.