Daikin r407c 2 pipe vrv ja fault code any offers?

Hi

I have a Daikin RSXYP5 with a JA fault. I have checked the thermistors and pressure sensors (transducer voltages) and confirmed with Daikin they're in range, this was at a standing pressure of 7 bar and has not been done with the system running.

I have good pressures in cooling. However, in heating I am reading 11 Bar suction and 18 bar discharge fluctuating slightly. It runs like this for a couple of hours and then pukes up the fault code.

On starting up this morning the pressures were up at 20 Bar+ disharge and 14/15 bar suction with an ambient temperature of 12 deg celsius.

(I also found that the controllers were scrambled with two displaying the master controller symbol and others switching between heating and cooling. I think I may have solved this by switching the pcb to Cool/heat (with system off) and making terminals A and C i.e forced heating mode. I think this is probably unrelated to the JA fault though).

JA = faulty discharge pipe pressure sensor.

Same fault code in cooling after 1 - 2 hours.

System has been in approx five years, serviced regularly and no problems to date.

I am heading back tomorrow to plug the checker in.

Any offers anyone?

Thank you.

Quote:

---

Originally Posted by Contactor

JA = faulty discharge pipe pressure sensor.

---

Replace the faulty sensor.

What makes you think it isn't the pressure sensor?

Did you find out why the suction pressure was so high in heat mode ?

Discharge to suction bypass ?

The 5v d/c pressure sensors can read ok at standing pressure but be way out at higher running pressure.
I had one last year on a R410a VRF system.
It was reading 10 bar lower than actual pressure. As the system was running in heating & outdoor unit target for about 30 bar in this case the actual pressure was 41 bar & running just under the HP switch cut out pressure of 41.5 bar.
We had off coil air temp at indoor units of over 70 deg C !

On some other VRF systems you can set the outdoor circuit board display for the pressure sensor data & then monitor while comparing with gauge reading to make sure sensor data is correct from standing pressure up to max discharge pressure.

Faulty main board!

Frank - transducers in range as stated in original post, never mind

sounds like an outdoor pcb

brunstar - faulty board as previous post

I had a similar problem with a three pipe system.
I never had a JA fault, I had a L6 fault. My Technical manual said it was a liquid pipe sensor but it turned out to be a discharge pipe sensor. the resistance was ok at ambient temp, but when the system ran and the pipe temp increased the sensor readings went up the wazoo. i replaced all of them for good measure, they were cheap and saved me coming back.

Ive got the same fault on a daikin, Replaced the discharge sensor last winter and the problem went away. Until this winter same fault JA again, Went out to the call this morning, Reset the memory on the system and started it up in test mode on heating, While in test i climbed through the roof space and checked all the zones and y pieces and duct connections all ok. System completed test run with everything ok. Customer said it only went on fault on really cold days, So i covered the out door air sensor with ice to simulate a cold day, But still the system worked ok. Could only get an E3 fault up by closing all the zones on heating. Any ideas? as the Daikin tech said if there isn,t a fault why are you ringing me.

Further to previous posts we were called back on the same JA fault despite changing the board. We have now changed the pressure transducer by unplugging the old one but leaving it on and fitting the new one onto a spare schraeder port on the HP pipework. This does away with the need to remove the gas for the repair.

This has done the job, it seems the transducer was only playing up intermittantly which led us to change the board. It compares with the HP thermistor to give the code.

Weirdly enough, we had exactly the same fault a few weeks later on a VRV3 2 pipe. This time there was no fault code, the inverter compressor was targeting a fixed speed but compressors two and three were being held off.

The first one was a 407c unit dating back several years but the second was only comissioned about a year ago so they sent the part under warranty.

As for Daikin tech, well, you take your chances.... you have to be qualified to speak to them now by the way, maybe it's to remind some of them what they're doing...

We have now changed the pressure transducer by unplugging the old one but leaving it on and fitting the new one onto a spare schraeder port on the HP pipework. This does away with the need to remove the gas for the repair.

Hi Contactor,

Up untill VRV 2 or 3, you can remove the pressure sensors without the need for removing the charge, they are fixed on "mushroom" connections like the Hitachi srcews.

Cheers

This highlights a major draw back with the Daikin VRV systems.

For example
On any Mitsubishi City Multi or Hitachi Set Free system you can monitor all system data from the outdoor circuit board display.
This includes the pressure sensor data.
So you can watch your gauges & monitor what the outdoor circuit board thinks the pressure is according to the pressure sensor data.

In this case its very easy to spot any problem with the pressure sensor data.

With the Daikin system you can only monitor the data if you have the service checker.

So in this case it has taken multiple visits to site over a period of months & fitting of parts to sort out the problem.

Daikin could make display of all system data at the outdoor unit or remote controller the same as other manufacturers
or
perhaps they have somthing to hide ?

The whole ease of use and programming methods on City Multi controls are way ahead of Daikin. It's easier and quicker to work on and can be mastered with minimal training.