The noise from an air conditioning unit can have lots of causes depending on the type of unit. These noises should not be ignored and are almost always a sign something that has gone wrong or is in the process of going wrong.

This troubleshooting problem brings you to a three-bedroom, ranch style home on a concrete slab, which, as most typically do in this area of the Southwest, employs a rooftop evaporative cooling system in the summer and an upflow forced-air gas furnace for heating in the winter. The customer says one of the bedrooms “just won’t get comfortable.”

Bob and Tim have been sent on a call to a house with no cooling. The system has just been installed and the construction crew has been having problems with startup. The system has a capillary tube metering device and Bob and Tim begin looking at what may be wrong.

This article deals with your personal safety when installing a new or replacement furnace. Topics covered include emergency procedures; clothing and safety gear; fall protection; electricity; lock out, tag out; GFCI; fuel safety; and confined spaces.

Bob and Tim were on their way to a residence where the occupants said their unit runs all day long, but the space temperature rises to 82°F while the thermostat is set at 75°. The unit shuts off during the night and the temperature inside is 75° in the morning, but during the day it rises.

In this month’s troubleshooting problem, you have been called by a colleague who is relatively new to HVACR to assist in repairing a split system in a manufactured home. The original diagnosis regarding this unit that is sitting dead was that the PCB 3-amp fuse was blown, and when it was replaced, the new fuse also failed.

Bob and Tim have gone back to the job with the grounded compressor. They changed the compressor yesterday and ran the unit for a few minutes, then shut the system down, leaving the crankcase heat on so they could start it up later. They now want to determine why the compressor burned.

For over 50 years, evaporative cooling products have been manufactured from hot-dip galvanized steel. Life expectancy of these units, when properly installed and maintained, has been excellent. In recent years, however, there have been reports of “white rust.” The critical fact that needs to be recognized is that white rust is preventable.

Bob and Tim were on their way to a no cooling call at a commercial building. When they arrived, they talked to the building manager and checked the thermostat. It was set at 72°F but the thermometer was reading 78°. Tim said, “The fan is running, so there is control voltage and the thermostat seems to be calling for cooling.”

In this month’s troubleshooting situation, our customer’s description of the problem is “not cooling” and “blowing warm air,” and the equipment that is supposed to keep this residence comfortable is a split system that has been in service for 16 years.