Service & Maintenance / Extra Edition

Troubleshooting Challenge: A Condensing Unit Problem

May 10, 2010
/ Print / Reprints /
ShareMore
/ Text Size+
Figure 1. (Click on the image for an enlarged view.)

This time around our problem centers on a split-system air conditioner. The condensing unit is 240-volt, single-phase, and the indoor air handler (which our customer is able to tell us is “blowing warm air”) consists of a standard gas furnace and an A-coil housed above the furnace plenum.

Since our unit is a split system, our diagram (see Figure 1) only shows segments of two distinct circuits because the problem is not with the indoor air handler. Both the condenser fan motor and compressor are PSC type motors, and the unit employs a high-pressure switch, low-pressure switch, and compressor safety thermostat for protection.

When you arrive at the customer’s home at 8 a.m. on a day that promises to be a warm one, you confirm that the wall thermostat is set in the cooling mode, and you also note that the fan switch is set in the AUTO position, and that the set point of the thermostat is below room temperature.

Moving outside to the condensing unit, you find it quiet, with no indication of attempts to start. Based on that observation, you use your meter to make specific voltage checks. Your results are as follows:

1. At L1 and L2: 240 volts

2. At T1 and T2: 0 volts

3. At test points 1 and 2: 0 volts

4. At test points 3 and 4: 0 volts

5. At test points 5 and 6: 24 volts

6. At test points 7 and 8: 0 volts

Your troubleshooting question: Based on the above tests, what direction does your troubleshooting take in order to solve this problem and get the unit back on-line?

Compare your answer with ours by clicking here.

For additional articles on troubleshooting, visit The NEWS’ HVACR In-Depth page.

Publication date: 05/10/2010

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

Recent Articles by Jim Johnson

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

Kyle Gargaro, editor-in-chief of The NEWS, hosted the 2014 ACCA CEO Forum. At the event, six well-known, highly respected company executives, Gary Michel, Ingersoll Rand/Trane; Chris Nelson, Carrier Corp.; Chris Peel, Rheem Mfg. Co.; Rod Rushing, Johnson Controls; Brent Schroeder, Emerson Climate Technologies; and Doug Young, Lennox; provided individual industry outlooks and fielded questions directly from attending contractors. Listen to the entire event on the NEWSMakers podcast. Posted on April 14.

More Podcasts

THE MAGAZINE

ACHRNEWS

NEWS 04-14-14 cover

2014 April 14

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