shooting A Follow-up on a Heat-pump Repair

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A Follow-up on a
Heat-pump Repair
BY JIM JOHNSON
New solenoid coil
[HVACR Instructors Note: The quarterly prize is now a
Fieldpiece LT-17A digital meter. Help your students win this
meter by encouraging them to submit their Troubleshooting
answer each month.]
Email your real-life troubleshooting problem—along with the
ultimate solution you found—to [email protected]. Be
sure to include as much supporting documentation as possible—
wiring diagrams, model/serial numbers, etc. If your problem is
published, you will be rewarded with a free heat-pump training
video, “Uncomplicating the Heat Pump: Refrigeration and Air
Flow Systems.”
T
his month’s troubleshooting problem involves a twoyear-old, 4-ton heat pump that was originally repaired
during the summer in response to a “no cooling” complaint. At that time, a failed reversing valve was replaced.
The service record shows that a new filter-drier was installed,
the system was evacuated to 500 microns and the refrigerant
charge was added by weight according to the manufacturer’s
specifications. There is no information on an evaluation of
the system’s performance after the repair.
There were also two subsequent service calls in response
to the customer’s complaint within a week that the system
was not performing properly after the repair. The service record shows that in both of those situations, refrigerant was
added to the system. Now, with the system operating in the
heating mode, the customer is calling again for service. Their
description of the problem is that the unit is not keeping the
building at a comfortable temperature and that it seems to
be running constantly.
Based on the information in the service record, you decide to accomplish an initial evaluation of the refrigeration
system in the heat mode by checking the indoor return- and
supply-air temperatures. You determine that the system is
unable to achieve an acceptable Delta T. Next, you perform
a test on the reversing valve (see Figure 1), checking the
10 RSES Journal DECEMBER 2015
Image courtesy of Carrier Corp.
SHOP TALK
troubleshooting
Fourth
port
Figure 1
4-port design
temperature of the discharge line at approximately 5 in. from
the point where it enters the valve body. You then repeat the
procedure on the connection leading to the indoor coil. Your
test shows a differential of 13°F.
Your troubleshooting question is:
What mistake was made during the
original repair of this equipment?
The answer to this month’s problem will be published in the February
2016 issue of RSES Journal.
If you have the answer to this question, submit your name,
home address, a day and evening phone number, the month
www.rsesjournal.com
TAKE THE CHALLENGE
Gas
Static
Differential
“
Their description of the problem is
that the unit is not keeping the building
at a comfortable temperature and that
it seems to be running constantly.
in which the question you are answering was published and your answer to:
Jordan Brandes, Associate Editor, RSES
Journal, 1911 Rohlwing Road, Suite A,
Rolling Meadows, IL 60008-1397; email
[email protected]; or fax to
847-297-5038. Make sure your
answer is submitted by Dec. 31, 2015.
All correct answers will be entered
into two drawings. The monthly
drawing will be for a copy of Johnson’s
video training program, “A Heat Pump
That’s Not Delivering Any Air,” and
the quarterly drawing will be for a
Fieldpiece LT-17A digital meter.
And the winner is…
The answer to the October 2015
Troubleshooting problem, “A Gas
Furnace That Will Not Fire,” is: There
is an open winding in the induced draft
WINNER
9 Michael Labanz
The
Pressures
You Need
Test
Pressure
Switches
motor and it needs to be replaced. The
winner of the monthly drawing (from
among 14 correct responses) is Michael
Labanz of Westfield, IN. The winner
should call 520-625-6847 or email
Johnson to facilitate shipment of
their prize. Drawing must be claimed
by Feb. 28, 2016.
Jim Johnson, Director of Training,
Technical Training Associates, develops
technician training workshops, DVDs,
audio books and e-books, many of which
are available at the RSES online store. For
information on Jim’s DVD training program, “Schematic Symbol Fundamentals
and Translating What They Mean,” visit
www.techtrainassoc.com, write PO Box
2259, Green Valley, AZ 85622-2259 or
email [email protected].
Westfield, IN
is the winner of theOctober 2015 Troubleshooting Challenge.
model SDMN6
Test Tools HVACR Pros Trust
www.fieldpiece.com
Circle Reader Service No. 52
www.rsesjournal.com
DECEMBER 2015 RSES Journal 11