Bob and Tim had just arrived at a service call, the first one for the day. The complaint was that the homeowner’s air conditioning had stopped sometime in the night and the residence was hot. After their initial checks, they suspected a low charge.

The equipment in this troubleshooting situation is a package unit heat pump and the customer’s complaint is that the unit is “blowing warm air.” When you respond to this service call, you confirm that the indoor temperature is near 90°F, and you also find that the customer has turned the equipment off while awaiting your arrival.

Bob and Tim were on their last service call for the day. It was an apartment house with a heat pump and the weather was warm during the day and cool at night. The tenant had just moved into this apartment and was trying to get the air conditioning to operate to her satisfaction and she said it was too breezy.

When equipment in the boiler room fails, it can be a building owner’s and facility manager’s worst nightmare. Whether a boiler is condensing or non-condensing, built with copper, cast iron, or stainless steel, it’s important to conduct a maintenance program to make sure systems remain in tip-top condition to avoid potential pitfalls.

Bob and Tim were at the house of a customer who said that her air conditioning unit did not cool well in the hot weather three days ago. She said the unit actually froze up and had ice on the outdoor portion of the unit on the big line. She shut the unit off and called for service.

In this month’s troubleshooting situation the equipment that needs servicing is a split system and the refrigerant flow control is handled via an electronic expansion valve (EEV) shown in Figure 1.

Bob and Tim had just arrived at the house of a new customer who explained that the air conditioning system was not working. The homeowner said that they had just had a warm day and the air conditioning system did not come on when they tried to cool the house down yesterday.

A thermostatic expansion valve (TXV) is designed to maintain a specific amount of superheat at the outlet of the evaporator. If the superheat value is too high or too low, the TXV may be the cause. However, before deciding the TXV is defective, all other system causes must first be investigated and ruled out.

Bob and Tim had just finished a routine service call on a house with a gas furnace for the heating system. They were talking to the housewife when she asked: “Our house is very dry in the winter time, and the humidity must be very low. How can we put a system in this house to keep the whole house at a higher humidity level?”

In this troubleshooting situation, the equipment is a split system that’s approximately five years old, consisting of a gas furnace to provide heat in the winter, and a condensing unit and “A” coil to provide summer cooling. There are actually three questions to answer in this problem.