forestcat
09-07-2021, 01:41 PM
Hello, I have an older 2004 Thermo King Unit SB-190 with 32,000 hours on it. Recently I noticed a strange thing. TPDF would be bad than before. When my box temp is around 45F is used to be around -12F, but recently during very hot days it was like -5 or even -3 sometimes. It all happened on very hot days temp outside 95F. Defrosting seemed to help a bit and on couple occasions to restore full TPDF to -12F. One time I observed what I think is a low suction pressure. Box temp was 31F, set temp was 0 (the unit was still precooling to set temp. Suction pressure was 8 psi, discharge was 251 psi and tpdf was around -10, etv 800.
On another occasion suction pressure was -2 psi. discharge was 330 psi tpdf -8. the reefer was parked in a loading dock at that time. i turned unit off and on . suction became normal at 30 psi and discharge 380 psi. tpdf roughly same.
I have no faults for the unit, during cooling ball is always up in receiver glass, pre trip pass with no codes. I cleaned condenser with warm water really well. Right now unit cools well and no complains. Where do i start? Does it all makes sense at all? Thank you
On another occasion suction pressure was -2 psi. discharge was 330 psi tpdf -8. the reefer was parked in a loading dock at that time. i turned unit off and on . suction became normal at 30 psi and discharge 380 psi. tpdf roughly same.
I have no faults for the unit, during cooling ball is always up in receiver glass, pre trip pass with no codes. I cleaned condenser with warm water really well. Right now unit cools well and no complains. Where do i start? Does it all makes sense at all? Thank you