The purpose of this article is to demonstrate the proper use of the pressure-temperature relationship, and to illustrate how it can be used to thoroughly analyze a refrigeration or air conditioning system.

In this edition of the Btu Buddy series, Bob and Btu Buddy meet for a training lunch after the previous day's low oil in the sight glass service call. Btu Buddy discusses oil and oil circulation in an A/C system.

In this installment of the Btu Buddy series, Bob encounters a compressor with very low oil level. Btu Buddy explains that the low oil level is a normal function of this system for this time of year.

In order to service and troubleshoot an air-source heat pump system, a service technician must understand the unit's sequence of operation. Where the system varies from its normal sequence is a major clue to any problems.

The problem: A piston-type reciprocating compressor has valve damage, or the valves are not sealing for some reason. The result: an inefficient compressor. This is one of the most difficult service problems to diagnose because the system may still have some cooling capacity.

In this edition of the Btu Buddy series, Bob works on a system that is not cooling properly and finds that refrigerant is flooding back to the compressor. Btu Buddy aids in pinpointing and curing the problem.

In this installment of the Btu Buddy series, Bob works on a water-cooled chiller with a high-pressure control that has the unit off. Btu Buddy assists him in inspecting the cooling tower and finding the problem.

Contractors are facing increasing pressures to be more productive. Armed with the proper tools and knowledgeable staff, savvy contractors can overcome today's challenges.