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?
Bob and Btu Buddy get together for breakfast to discuss their last service call, which concerned a compressor that had liquid refrigerant flooding back to it. Bob had asked a couple of questions while they were leaving the job. Btu Buddy then proceeds to answer Bob’s questions.
This time around our problem centers on a split-system air conditioner. The condensing unit is 240-volt, single-phase, and the indoor air handler (which our customer is able to tell us is “blowing warm air”) consists of a standard gas furnace and an A-coil housed above the furnace plenum.
This job is a three-story office building with an air handler on each floor with a refrigerant coil in each air handler. A 75-ton condensing unit serves the three 25-ton air coils. This is an old system that has still been doing a good job. The complaint is that the second floor unit is not holding the conditions that the thermostat is set for.
In steam systems that have not been maintained for three to five years, between 15 percent to 30 percent of the installed steam traps may have failed - thus allowing live steam to escape into the condensate return system. In systems with a regularly scheduled maintenance program, leaking traps should account for less than 5 percent of the trap population.
The day started with a call from the dispatcher who described a gas heat customer who had no heat. When Bob arrived, the first thing he noticed was that the furnace was cold. It had not been operating. At first, Bob thought that the thermostat was defective. Btu Buddy then arrived to clear up his confusion.
Your troubleshooting situation this time around relates to a walk-in refrigeration system in a busy restaurant that has experienced a compressor failure… specifically a mechanical failure. And it’s not the first time.