Daikin RZQ125KV4A

[Radlam]

Hi,

Could do with a bit of assistance with this issue.

Original fault code that appeared was L9.

Replaced a compressor and outdoor PCB on this unit, found a blocked expansion valve which caused the failure of the 2 components. Compressor got that hot, it melted the wiring harness to the compressor and damaged the board.

I have run the unit with the new compressor, outdoor pcb and expansion valve but the pressures seem all over the place in heating. Cooling seems OK. Head pressure will go anywhere from 350psi, to 500psi. Compressor is getting very hot again and I'm concerned its going to do the same again.

I'm wondering if the expansion valve is closing off too far and increasing the discharge pressure too high? Is this EEV controlled off a thermistor or pressure transducer?

Thanks in advance as always,

Rick

[Radlam]

I've also looked into the possibility of a leaking 4 way valve back into the suction? Is this common on daikin units?

[Brian_UK]

Are the condenser fans operating correctly?

The fans should run before the compressor starts, also do they rotate the same way?

[Radlam]

Are the condenser fans operating correctly?

The fans should run before the compressor starts, also do they rotate the same way?

Hi Brian,

Thanks for the reply,

Yes they start about 5 seconds or so before the compressor clicks in. Both the correct direction.

Are the condenser fans controlled off the HP pressure switch as opposed to a thermistor? I might check if a fan is stopping when the discharge pressure suddenly rises but I'm confident it didn't.

Thanks

Rick

[Brian_UK]

The fans are driven by the software not pressure switches.