Bob and Tim have arrived at Tim’s first service call. Tim asked Bob, “What is this call all about?” Bob said, “This is a new customer that wants us to take over the maintenance work for this apartment house.”

Btu Buddy has met Bob for lunch to answer some questions that Bob had about yesterday’s service call. Bob asked, “Why did that motor have two contactors and so many wires going to it? It seemed very confusing. I am glad that I tagged those motor leads when I disconnected the motor. I never would have figured out how to reconnect the leads.”

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.

Bob has received a call from the dispatcher about a system that is not cooling. The job is a small building with a 5-ton cooling unit. Bob went to the outdoor unit. It was running and all appeared normal. He went to the truck to get his gauges, and when he got back, he noticed that the compressor didn’t seem to be running.

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?”

Bob and Btu Buddy were on a service call yesterday where the compressor motor was running overloaded due to internal load; the bearings were dragging or worn. Btu Buddy told Bob, “Motor overload protection and circuit protection are subjects that need to be discussed later.” They’ve gotten together today for that discussion.

Bob got a call from the dispatcher to go to an office building that has a 3-ton heat pump compressor that has been shutting off after startup. The fan would continue to run. The building maintenance man said that he had observed the shutting down of the compressor several times.

Bob has gone on a service call where the customer is complaining that her house is not getting up to temperature. The house was heated with a heat pump with three stages of auxiliary strip heat. Bob removed the panel to the strip heat and found one of the units was not pulling current.

Bob and Btu Buddy have gotten together for a review of their last service call, which involved a control system that Bob was not very familiar with - pneumatic controls. Bob asked, “Why would anyone want to use air as the power source to operate the controls for a building?”

The customer’s complaint on this call was an overall overheating of his building. The manager told Bob, “We arrived this morning and the entire building was hot and keeps getting hotter.” He led Bob to the basement where there was a boiler. Bob found that the system had pneumatic controls.