Taking shortcuts while servicing refrigeration equipment can lead a technician to make costly mistakes. Not only can these mistakes be expensive; they can also cause harm to the equipment, as well as the technician.
It is important for a service technician to try and avoid taking shortcuts — even though this may be difficult. Many times a technician is backed up with more service calls than he can handle in a day. Although some shortcuts may initially save time, they may end up taking more time later on, and potentially costing the customer or service contractor more money.
SHORTCUTS TO AVOID
A technician should strive to avoid taking any shortcut that could lead to misdiagnosing a system’s problem. Some common shortcuts to avoid are: Not reading the high-side pressure and relying only on the suction pressure to troubleshoot a system. This simple shortcut may not seem to save much time on the job, but technicians often do this when trying to save time. The problem with reading only the suction pressure is that there are several system problems that may cause the suction pressure to be out of the correct operating range. Looking at both the suction and the discharge pressures is a better way to analyze the problem. On a thermostatic expansion valve system that seems to be cooling improperly, technicians may opt not to measure the superheat at the outlet of the evaporator. It takes time to get an accurate measurement, and it is often difficult to get to the sensing bulb location to take the measurement. Also, you need to wait for the thermostatic expansion to stabilize before relying on its reading. When adding refrigerant to a system, a technician should never assume which refrigerant is currently in the system. He should always verify the type used. Many times this is very easy. However, occasionally this takes extra time and work. Adding the wrong refrigerant, or mixing refrigerants, can lead to additional system problems. Not verifying that the voltage supply is truly off when replacing a component is a serious shortcut to avoid. This can be extremely dangerous for the technician, as well as the equipment. Just because the disconnect switch is in the “off” position, or the system switch is set to “off,” does not always mean that the power is truly off. A technician must always verify that voltage is off by using a voltage meter or voltage stick. There may be occasions when the disconnect switch has been bypassed or is defective and does not disconnect the voltage from the system. Not checking the condition of the start relay and start capacitor before condemning a capacitor-start, induction-run compressor. Although it may be a time-consuming task, a technician should always check the condition of the start relay and start capacitor. When a system that had been operating normally in the past is short of refrigerant, the system most likely has a leak. A common shortcut is to add refrigerant to the system and not even attempt to find the leak. The system runs for a day or two and then the technician is called out again for the same problem. Many times the leak is very small and difficult to find, but often the leak is large enough to locate with a little extra effort. Not checking the voltage directly at the motor terminals before condemning the motor. Sometimes it is difficult to get to the motor terminal to check the voltage. A shortcut to avoid is relying on measuring the voltage at a point leading to the motor and not at the motor terminal itself. There may be voltage leading to the motor, but at the terminals there may be a disconnected or burned wire causing the problem.
MANY MORE These are only a few shortcuts a technician should avoid. There are many more, depending on the type of system being worked on and the nature of the problem.
It’s admirable to want to save time on the job, but taking the wrong shortcuts can and will lead to problems for both the service contractor and the customer.
Marchese is owner of Coldtronics of Pittsburgh, PA. He can be reached at 412-734-4433; firstname.lastname@example.org (e-mail); www.coldtronics.com (website).
Publication date: 11/04/2002