Today I was doing a maintenance check on a three year old Carrier Heat Pump M# 38YKCo36 321 S# 4202EO2360. The high sub-cooling puzzled me. You see the unitlable listed an indoor sub-cooling requirement of 15 degrees. I started with a sub-cooling of 27 degrees. So removed 1 lb. of R-22 and resulted in following conditions: OAT-78, WB-58, LLP-240psi, LLT-89, SLP-60, SLT-46, RA-70, SA-47. The compressor amp draw was 17A and system has a TXV on coil. I tried to remove more freon to reduce SC more but suction pressure would drop below 60 and SC remained right at 25 degrees. Any suggestions why SC remains high while suction pressure drops so low? I have experienced similar situations to this befor, on some units, when trying to charge a TXV by sub-cooling to the unit lable listing.
The condenser was washed clean and indoor air handler and coil is three years old with clean filter and no outward sign of dirty coil. That is, blower and return air compartment are clean.
[Edited by book on 07-19-2005 at 11:04 PM]