Suppose you are testing a Copeland 3D (Discus) compressor and your ohmmeter registers OL from line to line on all of the 3-phase legs. The compressor is cold so you determine that the compressor is not off due to an overheat/internal thermostat trip. Your early assessment is that the compressor is bad and must be replaced. You call your supervisor who immediately sees a red flag when you say all 3 windings are open. It may be a defective “inherent protector”. This happened to a service tech that I supervised a few years ago. And it did have a bad protector.  Please see the following photo and wiring diagram for more information on how this all works and the numbers needed to obtain a replacement inherent protector. By the way, this part is located beneath the terminal plate and is mounted just above the motor windings in order to detect the first possible overheat situation.


Get ready Nashville for the much anticipated and most requested HVACR training experience.

Continue to monitor this website for information regarding registration for this seminar.


Danfoss, the pioneer of oil-free, magnetic bearing, variable speed technology, was recognized with the prestigious Product of the Year award during the 2018 AHR Expo for its Danfoss Turbocor® TTH/TGH high-lift compressors. 


I just can’t say enough about an app that has become an essential part of my life and the overall operation of our HVACR service team.

I am talking about EVERNOTE. It is one of the best ways to assemble, organize and present information that I have ever seen. Now you may be thinking that I am compensated for endorsing this product but you are wrong. I am compensated by using the product. I use it for training purposes as well. It has a great presentation mode that I use instead of powerpoint slides.

I use it many times per day. It is extremely useful when we have our weekly service huddle meeting.

Below is a screenshot sampling one of our huddle meeting frameworks.

You can easily hyperlink the topics to other notes that have been organized into specific Notebooks.

We also have the essential Notebooks shared with all the service techs. It is feature-rich and the beauty is that it syncs across just about all platforms.

An example list of our company shared Notebooks contain the following topics: Work Data, Parts Information, Site Information, Memos, Policies, Training, etc. In these Notebooks are contained over 500 notes and training presentations. It is easily searchable for specific notes inside these Notebooks.

As we go throughout the week and run across some useful topic to discuss or encounter a recurring issue, we add it to the list for “Monday” and we keep the team informed. It helps us to maintain a near-paperless approach to our day to day business practices. For all our larger digital files that contain operation manuals and other manufacturer information, we use Box, which contains over 12GB of technical information for our team to access.

My wife and I both have the premium version and use it for all our financial paperwork and household business. Click here to for a free trial of Evernote.


Model 250A is an auto ranging voltage monitor designed to protect 3-phase

motors regardless of size. It is used on 190-480VAC, 50 to 60 Hz motors to

protect the motors from damage caused by single phasing, low voltage,

phase reversal, voltage unbalance, and also high voltage. Added features

include the DPDT contacts that are used to perform two functions when

parameters are exceeded in addition to the standard adjustable restart delay.



One of the ways to assure that a customer’s case is performing as it should is to test the airflow. One of the best ways to do this is with a test instrument that measures feet per minute as illustrated.

Be sure to measure the airflow at the case discharge air outlet as illustrated below:

The manufacturer recommends that the best time to measure the case airflow is during the warmest time during defrost as the case cycle is terminating.

Below is a manufacturers chart detailing an example of a case specifications including the case design average air flow. Without the proper air flow, the case temperature will not reach the desired set point and the product integrity will suffer.

Rheem Opens Innovation Learning Center in Lewisville, Texas

Rheem is celebrating the grand opening of its newest Innovation Learning Center outside of Dallas. The Center is part of an extensive renovation and expansion of Rheem’s divisional offices, warehouse and distribution facilities at 1875 Waters Ridge Drive in Lewisville.


Members and guests got to check a fractional hp compressor for good/bad windings at the June 2017 Regular Monthly Meeting at the Middle TN Chapter. Jayson Goff, CMS was the seminar leader and had just returned from a winning battle over Stage 4 cancer. By the way, the compressor was deemed terminally ill by Larry Lynn, CMS and Doug Drake, CM, due to bad terminals.  😀

Indoor Air Quality Begins Here

The final factor in evaluating the air distribution in a space is the comfort of the occupants. In general, a person is thermally comfortable when body heat loss equals body heat production. What most people call a “draft” is simply a slight movement of air that results in a local feeling of “coolness.” It has been determined that a velocity change of 15 ft/min has about the same effect on comfort as a 1°F of temperature change. KEEP READING BELOW…..

A typical room air distribution system with local air velocities of less than 40 to 80 ft/min will satisfy 80% of occupants. Localized air temperatures should be less than 2°F below the general room temperature. The temperature near the floor should be less than 4°F below that at about shoulder height. For heating, local air velocities generally are below 40 ft/min. For cooling, local air velocities should be between 40 and 80 ft/min.



A defective expansion valve, refrigerant overcharge, or extremely low load may permit liquid refrigerant to reach the compressor from the evaporator. Because liquids are not compressible, the pistons and valves can suffer damage from such “slugs” of liquid.

To prevent this, you can put a suction accumulator in the suction line between evaporator and compressor. Trapped oil may build up in the bottom of the accumulator after the refrigerant evaporates. Accumulators therefore have an oil return line leading from the bottom of the trap.

This figure shows a cross section of a typical suction-line accumulator. It has a U-tube for passage of refrigerant vapor back to the compressor. The metering port at the bottom of the tube allows oil to return back to the compressor. The metering port is small enough that any liquid refrigerant entering should be boiled off before it reaches the compressor. EXCERPT FROM THE” TECHNICAL INSTITUTE MANUALS “AVAILABLE AT THE ONLINE STORE AT RSES.ORG.