Daikin VRVII trouble with maintaining setpoint

[Leigh]

I have a newly installed system REYQ46. I have a problem with 2 fan coils that dont seem to respond when temp rises above setpoint. Example cool 23deg room temp 26deg. When I change the set point to 16deg cool the fan coils respond.

Any ideas???

[Obi Wan]

Leigh,
What type on indoor units do you have, (model no Please) Do they have there own remote controllers?.
Check the room temp measured by the indoor units. You can do this by entering the service mode on the remote controllers.

Press the test button for 5 sec.
Press the test button again for another 5 sec.
You will now see code 40, press the temp UP button and select the code 41.
You will now see unit 00 and a temp value just below, this is the temp measured by the remote controller sensor.
Pust the dimond button once (from the test button, up 2 and 1 to right) and the display will read unit 01, The value just below is the temp measured by the fan coil unit.
If the units cool when you set the units to 16deg, then it must be the room temp measured by the remote controller or the fan coil unit is much lower then actual room temp.

Good luck.

[Leigh]

Thanks for your reply. The model number is FXMQ125MVE with individual BSV box. The room temperature is as indicated by the I touch controller, and confirmed by hand held thermometer. I f the rest of the building is at set temperature and only these 2 fan coils calling could it be a suction pressure transducer problem??

[frank]

Is the fan coil the last one on the pipework run, i.e. furthest from the outdoor unit?

Is the pipework within the limits i.e. last fan coil no more than 40m from first branch joint?

[Obi Wan]

Leigh,

Check the liguid pipe temp. when the indoor unit is switched off (same as the first post, but select unit 02) this should be the same as the gas pipe when th units is not cooling, however if the temp is much lower then the EEV may be letting by. If that is the case then the the indoor units have entered freeze protection and the stat is forced OFF.
Freeze protection kicks in when the liguid pipe drops below -1*C for 40 mins or -5*C for 10 mins. It will return to normal operation when the liquid pipe temp is above +7*C for 10 mins.
Try switching OFF all indoor units on this system for 15 Mins, (i.e. stop the compressors on the outdoor units) start up these units and see if they cool.

Obi Wan.