Faulty Daikin PC board???

[xtract]

I have a Daikin split ducted system which is playing up. On cooling mode it seems to be working ok but on heating mode it runs ok sometimes but other times when I start it on heating mode everything starts up apart from the 2 outdoor fans. The system runs for about 2 min or so and you can hear the outdoor coil getting colder and colder then the second the 2 outdoor fans start up the system cuts out. What could this be?

Thinking it may be a faulty PC board since the fans on the outdoor coil run on heating mode only sometimes and other times they turn on after 2 min which is too late and then the system cuts out the second the fans come on, obviously going out on LP. Would like to know how to confirm whether it could be the PC booard?

Model No. RY100KY1

[bobmarly]

Does a fault code come up on the wall controller when the outdoor unit cuts out?

[dogma]

Hey mate.

Check the Outdoor fans for free spin. By this I mean take the blades off both the fans and spin the shaft(s) with your thumb and middle finger. If you get 1.5 full revolutions on each then the fans are ok. If not, condemn the fans and the outdoor coms PCB.

Usually an over current fault will show. If the fans are partially seized, higher than normal currents are drawn through the outdoor pcb damaging the board.

I've been to a few jobs where this problem gives a compressor fault code but 90% of the time if you change the coms board, (the one the fans plug into), with the fans everything else is fine.

Hope this helps

[xtract]

The fans are ok because on cooling mode the outdoor fans come on straight away and the system runs no worries until you turn it off. But on heating mode everything runs the way it should apart from the 2 outdoor fans, after about 2 min the OD fans run for a split second then the system cuts out and the LED's on the PC board are saying a protective device has been activated which would be the LP safety due to the fans not running and the outdoor coil getting too cold and the pressure dropping too low.

Today I put it on cooling mode for a few minutes, then i turned it off and switched it over to heating mode, when the system started up on heating mode the OD fans also started up straight away and the system ran fine, but then i turned it off and then on again but the fans never started up the 2nd time around on heating mode, only on cooling mode.
So very rarely does the system run on heating mode with the outdoor fans running aswell.

Gas charge is ok.

[dogma]

Is there an A5 fault at all?

[dakesojo]

the outdoor fans are controlled by by the liquid line theromister checked omhs reading could be causing porblem

[Brian_UK]

The fans are possibly speed controlled so will not always power up at full speed. Just because they run in cooling does not clear a motor fault. Check for free rotation as suggested above.

The protective device could be the fan motors.

[Crash Pilot]

The fans are possibly speed controlled so will not always power up at full speed. Just because they run in cooling does not clear a motor fault. Check for free rotation as suggested above.

The protective device could be the fan motors.
Dont know if you have fixed the problem but try this.
Outdoor fans are controlled by ambient (air) thermistor behind outdoor coil.

Is the unit going out on LP control. Yes and no

These units keep the outdoor fans cycled off for up to 5min on the start of heating while the pcb collects data for defrost and also to prevent high indoor temp safety on heating due to the hot start function of the indoor fan. Keep in mind that these units were designed for the Jap fan coils. The Aust Ducted has a larger indoor coil.
The LP switch will not activate until the system goes into a vaccuum. The pressures are o.k but what happenes with these LP switches is that a number of them become faulty. With the outdoor fans off you get liquid returning back to the compressor that hammers the bellows on the faulty LP switch causing it to activate and shut down the outdoor unit.

Way to check. Gauges on the system (LP side).
Bypass switch on PCB. Put ohm meter across switch and start unit. The unit will now continue to run. Watch your meter and if the switch is open circuiting and you have a positive pressure the LP switch is the problem and needs replacing. They are a soldered type. This does not happen on cooling even though this unit does run 0k superheat you don't have the problem of liquid hammering the LP switch.

Second issue is if you have a remote sensor but this will not explain the safety activation LED on the outdoor pcb.
This unit needs a AKRCSO1-1 which is the same as the KRCS01-1. The difference is the AKRC has a capacitor across the sensor. If you use the one without the capacitor the sensor will fluctuate rapidly by about 20 degress. When you use AKRC you need to get the polarity right because the sensor is polarity sensitive. If you get it wrong then the sensor will read 20 degrees above actual temp. This means that the unit will only run on heat when it is really cold in the room. It will also overshoot and not cycle off on cooling. Can check this in mode 41 on the controller. Don't think this is the issue.
It will be the first problem I described.


Hope this might help