Screw Head Problem

[mwb]

Hello
My problem is I am getting old and losing it and I don’t work on this stuff a lot. I am working on a carrier 30hxa and head is high, with an evap. condenser. My D P is 190 psi (R-134A), S C T 108*, outside air 88*, L W T 44* and building load is low 70* R A. A 190 psi equals 127*. 127*- 88* is 39*, and the rule of thumb is 20*, but 108* - 88* equals 20*. The S C T is normal but the D P is high, then it is not from scale or tower sprayers. So if I am thinking right it is ether over charge or non condensables. I will isolate the evap. Condenser and test temps.

Your thoughts?

thank you

[mwb]

Hi
S C T was going to be my next question. I am rusty, no lost on that. There is no thermistor in the E C, I figure it is a calculation. If so from what does it calculate? This unit only has factory sensors, that means no O S A sensor. I used micro controller for S C T.

Micro only has four pressure transducers S P, D P, O P, and ECON P. They were 37, 190,133, and 75. three thermistors D G T, E W T, and L W T. They were 128*, 50*, 44*
How does it calculate 108* S C T ?

Thank you for the help