Tech Challenge – January 2012


Posted on:

A pop cooler utilizing R-22 with a TXV metering device (and receiver) has a customer complaint of warm pop. The symptoms at the convenience store confirm warm product and the condensing unit appears to be cycling on the low or high pressure control. What are the “possible causes” with the following measured conditions on this field service check sheet?

Field Service Check Sheet

Compressor Discharge Temp.

200 deg. F.
Condensing Press./Temp. 262 psig / 121 deg. F.
Condensing Outlet Temp. 115 deg. F.
Condenser Sub cooling 6 deg. F.
Condenser Split 46 deg. F.
Entering Feed Device Temp. 86 deg. F.
Evaporator Press./Temp. 55 psig / 30 deg. F.
Evaporator Outlet Temp. 40 deg. F.
Evaporator Superheat 10 deg. F.
Compressor Inlet Temp. 50 deg. F.
Total S. H. 20 Deg. F.
Ambient Temp. 75 deg. F.
Room/Box Temp. 49 deg. F.
Compressor Volts 240 V.
Compressor Amp. Draw Low

Share this challenge with your technicans to find out if they can figure out the problem. You can also share your thoughts here by posting them in the comments section below.

[note type=”tip”]Online Extra: Download this challenge in an attractive PDF handout form and share with your technicians.[/note]

And The Answer Is…

The possible causes for these conditions would center on a dirty condenser, blocked or re-circulated condenser air flow. These possible causes would cause the high head pressure/temperature and split. The low side is following the high side with higher pressures and the unit is likely cycling on the head pressure control.


Posted In: ACCA Now, Tech Challenge

Looking for an ACCA QA Accredited Contractor?

Are you a homeowner or building manager?

BECOME AN ACCA MEMBER

join now

PLUS It's Risk Free!

JOIN OUR MAILING LIST and Get the Latest HVACR Industry Updates.