Electrical Troubleshooting Using A Voltmeter

December 1, 2005
/ Print / Reprints /
ShareMore
/ Text Size+
It is of utmost importance for service technicians to understand voltage troubleshooting when servicing HVACR equipment. The majority of service problems are electrical problems, which usually cause mechanical problems.

This article will probe a bit deeper into voltage troubleshooting using a voltmeter.

The diagram (pictured at right) is of a 230-volt, single-phase electrical schematic of a typical commercial refrigeration system. The diagram includes a timer assembly with a defrost termination solenoid (DTS), evaporator fans, defrost heaters, temperature activated defrost termination/fan delay (DTFD) switch, low-pressure control (LPC), high-pressure control (HPC), compressor contactor assembly, and a compressor/potential relay assembly.

The system is drawn in the refrigeration mode. This simply shows what voltages would be measured across certain points of the schematic if a voltmeter were used in troubleshooting. The diagram also shows where Line No. 1 (LI) is in relation to Line No. 2 (L2) for ease of understanding the measured voltages.

Notice that anytime the voltmeter probes see both Line No. 1 and Line No. 2, 230 volts will be read on the voltmeter.

Anytime the voltmeter probes see the same line (L1 to L1 or L2 to L2), 0 volts will be read on the voltmeter because there is a voltage difference between the measured points. So, if the service technician can determine where L1 and L2 is when voltage troubleshooting, the rest comes easy.

John Tomczyk is a professor of HVACR at Ferris State University, Big Rapids, Mich., and the author of Troubleshooting and Servicing Modern Air Conditioning & Refrigeration Systems, published by ESCO Press. To order, call 800-726-9696. Tomczyk can be reached by e-mail at tomczykj@tucker-usa.com.

Publication date: 12/05/2005

Did you enjoy this article? Click here to subscribe to The NEWS Magazine

You must login or register in order to post a comment.

Multimedia

Videos

Image Galleries

2014 MCAA Annual Convention

Scenes from the 2014 MCAA Annual Convention in Scottsdale, Ariz.

Podcasts

NEWSmakers: Julian Scadden

Training is an ongoing process. Julian will discuss how you can generate maximum return on time and energy invested training by following a three part process. Listen to this podcast to get expert tips on training, tracking and follow up. 

More Podcasts

THE MAGAZINE

ACHRNEWS

NEWS 04-21-14 cover

2014 April 21

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

SERVICE CALLS POLL

Which statement on service calls best applies to your business?
View Results Poll Archive

HVACR INDUSTRY STORE

plumbing-hvac.gif
2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research

 

Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.

DON'T MISS A THING

Magazine image
 
Register today for complete access to ACHRNews.com. Get full access to the latest features, Extra Edition, and more.

STAY CONNECTED

facebook icontwitter iconyoutube iconLinkedIn i con