need help trouble in THERMOKING SB21O reefer

[ruben]

Is their anybody can help me in solving are problem with thermoking trailer.The problem is we cannot increase the discharge pressure to 275 psi and the liquid refrigerant is not visible in the sight glass in the liquid receiver that is should be.I already do the following change expansion valve,check 3 way valve for defrost,check-valve,bypass valve,charge with right amount of refrigerant,check the suction pressure,try to cover the condenser grille with cardboard and check the compressor all are working well but still it doesn't do anything.I try to swap the compressor to our other unit just to be sure that there is no problem with the compressor it runs okey.This start when I repair leak in the oil return pipe of the compressor then charge it with refrigerant R404a which is made from china.Is there any possibility that this refrigerant causing the problem.:confused:

[D.D.KORANNE]

What is the suction pressure ?

[ruben]

The suction pressure in the service valve is 70psi upon start up and goes down to 20psi as soon the box cool down.Below the throttelling valve is 20psi this mechanism maintaining this pressure before it goes to the compressor.Do you have any idea that you can share with me

[abet_meneses]

ruben,

At 20 psi and a refrigerant of R404 what is the box temp.what is your discharge pressure?

regards,

[ruben]

Thanks for replying we already solve the problem.It is cause by the Refrigerant we use thats is made in china and without brand name.Right now it is working well the box temp. is -25 c suction is 13-18 psi and the discharge is 275-300 psi.We use dupont Suva 404a.So dont use refrigerant that is made in chain and without brand name it will cause you a problem