September 2015 Tech Challenge

Posted on:

A rooftop[ utilizing R-410A with a TXV feed device has a customer complaint of insufficient cooling. The symptoms confirm inadequate cooling, and the compressor appears to be short cycling. What are the “possible causes” (not there is only one problem intended) with the following measured conditions on this field service check sheet?

Field Service Check Sheet

Compressor Discharge Temp. 240 deg. F.
Condensing Press./Temp. 444 psig / 125 deg. F.
Condensing Outlet Temp. 90 deg. F.
Condenser Sub cooling 35 deg. F.
Condenser Split 37 deg. F.
Entering Feed Device Temp. 89 deg. F.
Evaporator Press./Temp. 157 psig / 55 deg. F.
Evaporator Outlet Temp. 68 deg. F.
Evaporator Superheat 13 deg. F.
Compressor Inlet Temp. 73 deg. F.
Total S. H. 18 Deg. F.
Ambient Temp. 88 deg. F.
Room/Box Temp. 78 deg. F
Compressor Volts 240 V.
Compressor Amp. Draw High

Looking for the answer? Check back on October 30, 2015.


Posted In: ACCA Now, Tech Challenge

Looking for an ACCA QA Accredited Contractor?

Are you a homeowner or building manager?


join now

PLUS It's Risk Free!