Hi,

I had been trouble shooting a 6 ft upright standing double door freezer at a Thai restaurant. The Carel controller is set to -19 and it can only achieve -10 degrees at its best.

Previous techs have swapped the compressor, fitted new evap fans and to no improvement.

Ive checked:

Evap fans (x4) are all operations
Evaporator and condenser coils are clean/clear
Checked suction pressure at compressor and getting 20psig/-25 on R404A...

The system has a CPR valve and the press. before the valve is about 20psig ... then it goes up to 40 psig (-10) at intervals... then drops... back to 20psig... all the while the suction line does not feel very cold at all in a freeze cycle and only frosts over during hot gas defrost (indicating the CPR valve is doing its job?)

The lowest we have achieved is -14 and cannot get the desired -19 set point. The system is on capillary expansion, so should that signal alarm bells when theres a CPR valve fitted?

Your advice would be greatly received.

C