Bob was called to a job that had a no cooling complaint. This was a new customer and Bob wanted it to be a good experience for the customer. It was a small stand-alone store building with a 3-ton cooling only unit. Bob determined this was a low charge problem. He installed his gauges and discovered the unit did not have any refrigerant in it.

In this troubleshooting situation, we have a customer who has called to say that their 12,000 Btu through-the-wall unit is “blowing cool air even though it’s set for heat.” The unit is a heat pump with a three-speed motor. It operates on 240 vac.

Although a capillary tube can become totally restricted, a far more common problem is when it becomes partially restricted, allowing some refrigerant to flow into the evaporator but not enough to satisfy the requirements of the system. This seemingly easy problem to diagnose is actually rather tricky at times.

The dispatcher called Bob and sent him to a job that really sounded like a problem. There had been a hard rain and a customer had a condensing unit that had been under water that morning due to high water from a creek behind his house. The owners were on a fixed income and wanted to get the repair at the best possible price.

Fire and smoke dampers are a proven and effective way to protect duct and air-transfer openings in walls, barriers, partitions, corridors, and shafts. This article includes the basic testing, installation, and maintenance requirements for life safety dampers.

Thermostatic expansion valves (TXV) are responsible for metering the proper amount of refrigerant into an evaporator coil. When they fail, they either cause the evaporator to be flooded (overfed) or starved (underfed) for refrigerant. Read more and find out how to diagnose a defective TXV.

Bob has been on a job at a convention center with a 100-ton water cooled condenser. The owners are anxious for Bob to get the a/c back on, but Bob said the tubes must be cleaned before the unit will run. He has called the shop and asked for a helper and a tube cleaning machine to help him get the unit running as fast as possible.

Your role in this month’s troubleshooting situation is as the follow-up technician on a problem that was made worse by the technician who preceded you. When the restaurant manager originally called for service, the complaint was that their small walk-in cooler “wasn’t keeping as cool as usual.” Now it’s “hardly cooling at all.”

The dispatcher calls Bob with an urgent service call from the city’s convention center. A convention is going on and the air conditioner is off, and it re-starts but only runs a short time and shuts off again. The maintenance man said he had to reset the high pressure control to get it started. Btu Buddy assists in troubleshooting the system.

Anyone whose job involves servicing electric motors has encountered the problem of a missing nameplate. Other articles in the Motor Doctor series have covered ways of determining the specifications of a motor lacking the nameplate, but what if you are trying to figure out how to wire that motor?