Daikin twin not ramping up on heating

[r.bartlett]

Chaps

got a 4kw twin split 2012.

both indoors run on cooling as normal. but on heating the unit will only ramp up to 240psig and hence no real heat effect

The refrigerant charge is correct so I'm thinking it's possibly sensor ?

suggestions etc

richard
(not always sunny Tenerife)

[Peter_1]

Hi Richard,

Can this help?
http://www.refrigeration-engineer.com/forums/showthread.php?25988-Daikin-inverter-not-ramping-up

Peter (This morning everything covered with snow and -3°C)

PS: Is your back healed again?

[hyperion]

Make and model please might give us a little more of a clue.

[frank]

Hi Richard

It could be the indoor coil sensor or the outdoor discharge thermistor out of calibration.

In cooling mode, the indoor sensor is used for freeze up protection, but in heating, it is used for holding off the indoor fan until the coil temp is above 34C to prevent cold draughts. In the meantime, the compressor will hang back waiting for the indoor signal to ramp up.

If the compressor discharge thermistor is reading incorrectly then the unit will prevent the compressor ramping up due to discharge protection control.

[Peter_1]

With this free app from Daikin, you can find the resistance values
Without this app, I can't service a VRV :-)
https://play.google.com/store/apps/details?id=com.daikin.aircon&hl=nl

[r.bartlett]

Returned to site today.
Thought I'd go through a run again before pulling it apart.. As you'd expect both indoor units ramped up to full heating. 45 minutes later everything worked as normal

Left alone till the next time it fails

Thanks to all.