Our troubleshooting problem involves a split system heat pump in which the outdoor unit is operating in an 85°F ambient, and when you arrive in response to the customer’s no cooling complaint, you find the indoor fan operating normally, and you also note that 240 volts is read at L1 and L2 of the outdoor unit.

Bob and Tim were doing a routine service contract call. They had fastened gauges to the compressor at the condensing unit and had a temperature lead fastened to the suction line at the evaporator coil. They were observing the pressures and temperatures and Tim said, “The suction pressure is not stable. Isn’t it supposed to be stable during a long running cycle?”

To establish the openings for return air grilles, you can use a frame made on the job from sheet metal. It forces the wall hangers to cut the return air openings as they install the sheetrock.

Bob and Tim have been tuning up a system with an orifice metering device for the correct evaporator charge, when Bob said, “There is another verse to tuning up a system, and it’s called subcooling.”

In this month’s troubleshooting situation, our customer has called to say that the roof-mounted gas pack on their 1,500-square-foot home isn’t keeping them cool. Their specific description of the problem is that they “can’t feel any air” coming from the supply registers.

Bob and Tim were on their way to a no cooling call at a residence. They were pretty sure that it was a low refrigerant call. Bob said, “I hope that we can put the last lesson into practical practice. We have gone to a great deal of trouble to understand superheat.”

Loose electrical connections to motor terminals can cause voltage drop, overheating, and a chance of fire. For three-phase motors, a loose connection can cause single phasing — which will damage the motor.

Bob and Tim were in the company conference room where Bob is set to give Tim some extra training at Tim’s suggestion. Bob said, “Tim, you asked for more explanation of what superheat is. This is not a very simple topic. It will take a couple of meetings to go into detail about it.”

In this month’s troubleshooting situation, the customer hasn’t called because their HVAC system has stopped cooling. You’re there because they’ve requested a preventive maintenance check of the five-year-old equipment to determine if there are any potential problems that would affect the system performance in the future.

Bob and Tim were driving to the job they left yesterday and talking over what needs to be done today, when Tim asked, “How are we going to move the condensing unit we disconnected to the new location so we can connect it to the system where we disconnected the defective condensing unit? You said you had a plan.”