Tech Challenge – July 2014


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A split air conditioner that has been retrofitted from R-22 to R-438A (M099) with a TXV metering device (and receiver) has a customer complaint of “warm, no cooling”
The condensing unit appears to be running 100% of the time. What are the “possible causes” (Note: The unit was retrofitted per the manufacturers guidelines and there is only one problem intended) with the following measured conditions on this field service check sheet?

Field Service Check Sheet

Compressor Discharge Temp. 220 deg. F.
Condensing Press./Temp. 195 psig / 95 deg. F.
Condensing Outlet Temp. 81 deg. F.
Condenser Sub cooling 14 deg. F.
Condenser Split 10 deg. F.
Entering Feed Device Temp. 81 deg. F.
Evaporator Press./Temp. 50 psig / 32 deg. F.
Evaporator Outlet Temp. 51 deg. F.
Evaporator Superheat 19 deg. F.
Compressor Inlet Temp. 75 deg. F.
Total S. H. 43 Deg. F.
Ambient Temp. 85 deg. F.
Room/Box Temp. 80 deg. F.
Compressor Volts 240 V.
Compressor Amp. Draw Low

Check hvac-blog.acca.org in early September for the answer.


Posted In: ACCA Now, Tech Challenge

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