problem with EXV on Daikin UATYQ

[blacktigra]

Hi everyone.
We have a problem with Daikin UATYQ600 rooftop unit.
Each 20-30 minutes we have “high discharge temperature alarm” on 1st circuit. We check all sensors, EXV motors on each circuit, replace main and EXV PCB’s – nothing help.

During the commissioning I found some strange behavior of EXV's. Without any explanation of their logic, I really cannot understand how they control suction superheat.
EXV1 always tends to open, EXV2 – to close.
I try to make a log file, but not all parameters in it. Please find it in attachment.
UATYQ.zip

Just after startup and during first 10-15 minutes of operation everything seems to be normal.
But when some time is passing, EXV on first circuit start to open, IND HEX 1 temperature drops down.
After couple of minutes this temperature stars to rise, and discharge temperature is rising also.

Rooftop working conditions: outdoor ambient temperature 30-35C, suction air temperature doesn’t fall below 24-25C. Supply temperature about 18-17C.

This unit is completely new, and was put in operation just two months ago.
Also, we check refrigerant charge – it is according to specs for this unit – 10.4 kilo per circuit.

Maybe somebody have an explanation of EXV logic? I cant find it on extranet, FQS doesnt provide any answer.
Thank you in advance for your help.

[RusBuka]

Sh, sc, dsh

[blacktigra]

Solved. Wrong wiring from the factory.

[Deano240]

What was wired wrong

[blacktigra]

What was wired wrong

EXV PCB. They was reversed.

[Magoo]

Add voltage surge protection saves cooking PCBs