daikin ry140kuy1 ducted LP fault

[paul_h]

I've got a ducted daikin here that isn't running right.
On heat mode, the fans aren't working properly, causing flood back and LP faults.
The compressor starts and runs for 3 min while the fans don't run at all. SP is 100kPa, HP is 1500kPa, suction line full of liquid
Then after 3min the outdoor fans run on low speed for a minute then the system cuts out. both fans do the same thing, either both don't run, or both start up on low speed after a few mintues of compressor operation.

Fan capacitors are OK. Fan motor windings for one is red-black(110 ohms), R-blue (150 ohm) R - orange (375 ohm). Black - blue (41 ohm) BK - orange (264 ohm) Blue - orange (223 ohm).
The other motor in the same order is (95 ohm), (130 ohm), (325 ohm), (36 ohm), (231 ohm), (195 ohm).

The coils on the relay mounted PCB are all OK and 360 ohm. No power from the PCB to the fan motors when they aren't running.

The indoor thermistors are both 25k ohm at ~20C, indoor unit FDYM06FAV1

Anyone come across a similar problem? This system is a few years old and has worked fine for a while.

edit: No fault indicated either, green LED is flashing normally and both red LEDs are off.

[Temprite]

Hi Paul.

Sounds like indoor coil temps are high causing outdoor fans to only operate on low speed.(Assuming that unit is on heating) You can check from wall control.

Had one tripping on LP once, bridged out control and put meter across disconnected control and ran unit. LP control intermittently opened every couple of minutes. Apparently this is common with these units.

3 minutes of compressor operation? does it fail on LP or is it cycling on temp? That a short on period.

[rude]

Warentee if its only a few years old?

[Yuri B.]

Some strange lag between compressor and evap (o.u.) fans. Liquid instead of hot gas in the thick pipe - no evaporation? Maybe try to switch fans of the o.u. directly ? (after comp starts) and see what changes.

[paul_h]

Hi Paul.

Sounds like indoor coil temps are high causing outdoor fans to only operate on low speed.(Assuming that unit is on heating) You can check from wall control.

Had one tripping on LP once, bridged out control and put meter across disconnected control and ran unit. LP control intermittently opened every couple of minutes. Apparently this is common with these units.

3 minutes of compressor operation? does it fail on LP or is it cycling on temp? That a short on period.
Yeah but isn't the normal operation to start the fans on normal speed when the compressor starts, and then cycle the fans on low or off if there's a high indoor temp?
This compressor runs solo for 3 min before the fans start at all, and it's slugging liquid.
The SP is only a 100kPa, but I don't know if its cutting out on LP because no fault LEDs come on, no matter how many times it cycles.

[Temprite]

Yeah but isn't the normal operation to start the fans on normal speed when the compressor starts,

Cant remember, probably need to talk to tech line to be sure.

My memory is pretty lousy, but......

I reckon we had same model unit once approx 6 years ago doing the same thing and outdoor unit was icing up. I'm sure outdoor fans didnt start up straight away.When they did start running it was only for a very short period. Unit was short cycling due to return air heating up too quickly and unit cycling on temp. Remote sensor was installed which allowed unit to run longer and cured problem.

Return and supply air ductwork was also restricted which made problem worse.

Couldn't set wall controller to for temp control as it wasn't available as an option for this model.

Maybe you could test run the unit and see if the fans start running once unit runs for a while.

Good luck......

[paul_h]

Cheers, but how do I get in contact with daikin tech?
rude, I'm looking into the warranty angle, but I don't know exactly how old the unit is or who installed it. If there's some way of finding out by the unit's serial number, I'll go down that path.
This isn't a one off call out, this is a business I work for, servicing all their buildings (about 6 buildings and 20+ a/cs), this daikin is in their own office though. So I need to work out what is wrong before I palm the job off.

[Temprite]

Cheers, but how do I get in contact with daikin tech?
rude, I'm looking into the warranty angle, but I don't know exactly how old the unit is or who installed it. If there's some way of finding out by the unit's serial number, I'll go down that path.

1300362438

Quote model and serial number to the girl that answers phone at reception she should be able to tell you when the unit left Daikin and even who installed it. Helps if you have an account with them.
I doubt that unit is still under warranty.

[paul_h]

I went back today to do some thermistor readings.
All the outdoor thermistors seemed OK, tested at 22C, Discharge was 31K ohm, air was 26k ohm coil was 26k ohm.
I tested voltage too just in case there was any cable damage that a multimeter couldn't pick up. Both air a coil thermisters were reading 3.18V DC across, so they look good.

It was warmer today so the unit ran a little longer when testing.
Looking at the inside the coil thermistor seems good. As I said the other day it tested out at 25 k ohm at 20C.
This time I checked the indoor fan operation. The fan ran on low speed for a few minutes until the coil heated up, then it automatically switched itself to high speed as it should have, so I can't see a problem there.
The outdoor fans weren't running at all during this time, even though the indoor thermistor obviously wasn't reading a high indoor temp (ie it was on low speed wating for the coil to heat up for a while)
Air flow was decent, air on/off the indoor was 22/30C

[exotiic]

Hi Paul,

I had a similar issue this morning with an ACTRON SRE18C condensing unit on heating mode with the outdoor fans not running correctly, They would start with the compressor and run for approximately 30 seconds and then cut off. Compressor would keep running and the board would not be calling for the condensing fan to run. As with your system the system was building up liquid inside the suction line and suction reading down to 150-100kPa and discharge at 1200kPA.

Outdoor fan caps were out of range at 4.3 and 3.6 microfarens when rated at 5 so suspected could be an issue but didnt have a problem starting the motors under load. I initially suspected that perhaps the outdoor coil may have been faulty as there was the suspect code appearing on the board as well as the high low pressure control failure so bypassing the high and low pressure controls wanted to check the baord and the coil sensor. Without high low controls in the system condensing coil would ice up with coil sensor out and measured at ambient temp of 17degrees the coil sensor read at 15kohms which according to tech rep was accurate (though he couldnt tell me much else, as if reading from a book).

Reconnected the sensor into a slightly different position into the coil at same height and reconnected into board and system was running absolutely perfectly for two hours in operation while testing. Allowed system to cycle on and off and inspected start up and worked to correct pressures of 450kPa and 2100kPa every time. Is it possible that it could be a faulty sensor in your system or am I just on a wrong avenue?

Regards

Frank

[paul_h]

That's what daikin have told me, a possible faulty sensor.
But they checked out OK, not only by resistance (which is never a 100% reliable test), but they checked out by voltage too (which is a 100% reliable test*).

So I've done something I hardly ever do, gave up as I'm out of ideas and have no service manuals for it, so I just ordered a replacement PCB hoping that will fix it :D :D

* After all that is what the PCB is reading, the voltage across the sensor at certain temps. A fracture in the cable could deliver a k ohm reading, but not have a decent voltage flow across it.

[exotiic]

How do you know the exact voltages for each sensor as obviously every branded unit and component is different? The tech rep didn't have such information and only wanted me to check the resistance. After that he insisted on changing the hp and lp sensors claiming that theyd be the cheapest method, even though they were already taken out of the equation by bridging the baord and secondly would require a complete evacuation of the system as there were no isolation valves. Then he pushed for a board malfunction because it seemed most logical.

I believed the board was fine and it appears to be so without the need to so far change any components.

[rude]

That's what daikin have told me, a possible faulty sensor.
But they checked out OK, not only by resistance (which is never a 100% reliable test), but they checked out by voltage too (which is a 100% reliable test*).

So I've done something I hardly ever do, gave up as I'm out of ideas and have no service manuals for it, so I just ordered a replacement PCB hoping that will fix it :D :D

* After all that is what the PCB is reading, the voltage across the sensor at certain temps. A fracture in the cable could deliver a k ohm reading, but not have a decent voltage flow across it.
Did you order new sensors with the board just in case?

[paul_h]

How do you know the exact voltages for each sensor as obviously every branded unit and component is different? The tech rep didn't have such information and only wanted me to check the resistance. After that he insisted on changing the hp and lp sensors claiming that theyd be the cheapest method, even though they were already taken out of the equation by bridging the baord and secondly would require a complete evacuation of the system as there were no isolation valves. Then he pushed for a board malfunction because it seemed most logical.

I believed the board was fine and it appears to be so without the need to so far change any components.Well normally I get that info, Samsung and fujitsu give out voltages as well as resistance, but with this system it was an educated guess.
Because another sensor with the exact same resistance had the exact same voltage, so either both are bad, or both are good.
I'm flying by the seat of my pants as I can't get a lot of daikin info except from a few solid members here. When I post here it's always that situation, there's hundreds of units I look at that I know well and never posting threads here.

Sometimes you have to go with what is the most likely rather than just replace everything. I may be wrong, and in the end daikin tech and everyone else may be wrong and it may be the indoor PCB/sensors faulty in some way.
Unfortunately with daikin I'm still in the learning and trial and error mode. Most other brands I know like the back of my hand but as I've never worked for a daikin installer it's a more difficult diagnose as I've never got much experience or info on them besides fault codes, and this unit isn't giving any.

[exotiic]

I just got a phone call this morning indicating that the system has returned to its previous state. So I might be looking at a board change too or a sensor.

[paul_h]

You having problems as well?
I changed this board and it's still doing the same thing.
Starts up the compressor, fans don't run for 3min or more, during this time everything is icing up and the LP is very low.
After about 3min, then fans kick in on low speed.

Worse still I think the compressor is going to die soon due to it slugging liquid as it makes a bit of a grinding noise when shutting down, and a louder than normal 'bang' on start up.

[lowcool]

dont know if it applies here but is the communication wiring seperate to the power supply or has only one earth.
just trying to think out of the square fellas

[exotiic]

I actually went back today and when I got there they told me that whilst yesterday it was showing symptoms of earlier issues as mentioned above, today was working perfectly. I had a newer board with me and a replacement coil sensor as I told them that it would most likely be a board or sensor issue as per our observations, but at quoting of cost, they insisted after working well today to try the sensor first.

I replaced the sensor but on first start up after replacement the system would start as it has been; condensing fans would start for 30 seconds then switch off whilst compressor was running and again ice up as with you Paul. However, when reset system to start again it would work everytime perfectly as per the last visit and as per when i arrived on site. It seems to be on the first initial start to have this issue then it seems to run perfect. I changed the suspect fan capacitors in the process also.

I wanted to check the voltages coming from the indoor unit and from the coil sensor when the fan was ordering to turn off but it didnt again so I could only test as were working. Indoor connection was providing 14.2VDC and the coil sensor was ranging from 2.3-3.1VDC (im guessing as resistance grew due to coil temp).

Lowcool, on this particular system, you are correct the comm wires are seperate and earthed individually.

[rude]

dont know if it applies here but is the communication wiring seperate to the power supply or has only one earth.
just trying to think out of the square fellas
i think we have to think inside the square. Im not too clued up on daikins but we need to know what controls the fan motors and speed of them? I would think its the sensors or is it something else?

[paul_h]

... need to know what controls the fan motors and speed of them? I would think its the sensors or is it something else?
Yes that's exactly what I need to know but nothing except a full service manual would tell me, and I can't find a proper manual.
Normally the indoor pipe temp sensor would tell the fans to stop, and the outdoor ambient and pipe temps would tell the fan it needs to run on heat, with just the outdoor sensors telling it to run on cool.
What I've found:
The indoor sensor seems to control the indoor fan normally, (ie low speed untl the coil warms up), and it's resistance checks out fine too. (Can't measure voltage there due to where the indoor unit is)

The outdoor fans work on high speed in cooling mode, the resistance and voltage for those sensors also seem to be OK. That is, the resistance is in spec and the voltage varies between 3 and 4.2V depending on pipe temp. So the fans, capacitors and sensors seem OK.
I'm dreading tomorrow when it's a cold morning and the system ices up and short cycles again :(

edit: Also I checked the cables and sensors to make sure there's no damage and they're clamped securely to the coil.

[rude]

Have you tried holding or putting the sensors in ice cold water and seen if the fans start?

[paul_h]

OK this is weird, I've found nothing wrong with this system, that's just what it does. There's another daikin ducted split (smaller and different model, same vintage and style, just a couple of sizes smaller) in a different building that does the exact same thing. Comp starts without fan, suction starts getting full of liquid, pressure really low, and then the fans start up. What the hell?
Every other brand turns down/off the outdoor fan later on if/when necessary due to high indoor coil temp, the default is run the fan as fast as it can, the brands I'm familiar with do not delay the outdoor fan for as long as possible!?

edit: these aren't inverters or anything, so basic controls like every other manufacturer should suffice, turn off the fan to reduce indoor coil temp if necessary, so why are they delaying outdoor fan on comp startup?

[nike123]

Do you have model#?

[marc5180]

It's in the title....... daikin ry140kuy1

[nike123]

It's in the title....... daikin ry140kuy1

I am now officially blind! :D

[frank]

Hi paul

What's the ambient temp when this phenomenon occurs?

according to the data sheet, the maximum temp for heating operation is 15C

http://pmd.daikineurope.com/Consultation/Internet/Display2/techdata.jsp?id=9061&locale=en

[paul_h]

Well it's been about 15-20C when I've been checking them during the middle of the day.
It doesn't get that cold here, 12C is a very cold day for perth :D , only gets down to about 3C overnight min.

[frank]

That may be your problem then. If the ambient is above 15C the system will just hang when you are trying to heat.

Try cooling the outdoor thermistor down with a wet cold rag and see if it kicks in.