July Tech Challenge

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Share this challenge with your staff and see who can figure out the diagnosis first.

A commercial split heat pump system in the cooling mode @ 88° F outdoor ambient, utilizing R-410A, has a customer complaint of no cooling. The system has TXV metering devices on the indoor and outdoor coils with check valves. The symptoms at the business confirm that the compressor and indoor blower are running continuously. What are the “possible causes” with the following measured conditions on this field service check sheet? Note that in the cooling mode, the condenser is the outdoor coil, and the evaporator is the indoor coil.

Note: There is only one problem intended.

Field Service Check Sheet 

• Compressor Discharge Temp. 109° F. 
• Condensing Press./Temp. 295 psig / 94° F. 
• Condensing Outlet Temp. 90° F. 
• Condenser Sub cooling 4° F. 
• Condenser Split 6° F. 
• Entering Feed Device Temp. 88° F. 
• Evaporator Press./Temp. 101 psig / 32° F. 
• Evaporator Outlet Temp. 36° F. 
• Evaporator Superheat 4° F. 
• Evaporator Split 48° F.  
• Compressor Inlet Temp. 48° F. 
• Total S. H. 16° F. 
• Ambient Temp. (Outdoor) 88° F. 
• Room Temp. (Indoor) 80° F. 
• Compressor Volts 240 V. 
• Compressor Amp. Draw low 

Check back during the first week of August for the answer!

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Posted In: ACCA Now, Tech Challenge