When a refrigeration system fails, many times the cause can easily be diagnosed. However there are occasions when the cause cannot easily be determined - either the true cause is unclear or the technician is unsure of a problem. How do you work through these jobs? One method used by some techs is to “read and record.”
Bob got a call to go to a convention center where the air conditioning system was not working. It was a 75-ton unit with one compressor. The system was many years old, but had been functioning fine, until now. After checking out the unit, an ohm check showed 0 resistance to ground.
A variable frequency drive (VFD) fails to vary the discharge-air fan speed. A motor overheats and fails prematurely. While each troubleshooting problem in an HVAC system presents its own unique set of circumstances, HVAC professionals may recognize such problems as possible power quality issues.
Actually, frost on the suction line only indicates that at the location where the frost is present, the suction line piping is below the dew point temperature of the surrounding ambient air and at or below 32°F. That’s it. It is neither an indication of a properly operating system nor a system defect.
It is the time of year when I get calls for heat pumps not cooling properly. With a little prodding, I usually hear that the past month’s electric bill was also high, even though it wasn’t that hot. These calls always raise one major red flag for me. One of my first questions is if the heat pump is properly elevated up off the pad.
The process of brazing ACR tubing is a common task for many refrigeration technicians. Although this is relatively simple, there are some system problems that can occur if some basic brazing procedures are not followed.
Bob has been sent on a service call where the customer is complaining about her power bill. She thinks that the heat pump may be the problem. Her power bill is much higher than last year. She explained this to Bob and he started by asking a question, “Does the auxiliary heat light come on very often on your thermostat?”
Accurately troubleshooting and repairing refrigeration systems requires technicians to use many specialty instruments. They base many of their diagnoses on what is read from these instruments. Relying on them to be consistently accurate day in and day out is a must. If these tools are inaccurate, more than likely the diagnoses will be inaccurate.
This article is part two of a two-part series on ice flake machine troubleshooting. The last article, which appeared in the Feb. 7 NEWS, examined troubleshooting low and high water levels. This article will examine water impurities and mechanical problems.
Air conditioning coil cleaning is an important air conditioning maintenance procedure that sometimes takes some patience, and usually takes a lot of water. First, you have to make some common sense evaluations.