daikin ry125

[Dunno_Daikin]

Hi, I've got a daikin I'm looking at that cuts out in heat mode.
ry125kuy1.
person says it cuts out on heat and blows cold air.

Checked the air flow and the fan cut in and cut out with indoor coil thermistor/outdoor operation. That seems to cycle the fan properly.

But I forced a defrost and it cut out on HP fault (e3) after a few minutes and the indoor fan then switches on and runs constantly and blows cold air.

This leads me to believe, that whatever is giving them a fault must be HP or LP fault?

Why did the system cut out on HP when I forced defrost? Yes it wasn't iced up, but why didn;t it terminate defrost. Does this even prove anything?

I don't get daikin at all. Eg reading their manuals (not that I have once for this unit), if the outdoor temp is above 9C, and the indoor above a certain temp (i think), the out door fans won't run for up top 5min. The LP is only bridged out for 3 min though!!!!!!!!!!
so I usually get a lot of LP faults happening after 3min. So I hate daikin and don't understand them.

But anyway, On heat mode before I touched forced defrost this system:

R22, 19C ambient, and of course the outdoor fans not running for 5min, so waited 10 min before checking data. Before checking, outdoor thermistor 25Kohm, coil thermistor reading 25kohm

HP 1500kPa
LP 380kPa

Indoor air 20C on, 36C off
outdoor air 19.5c on 6C off

Discharge temp 68C
suction temp 1.5C

Bt there's just a sometimes nuisance cut out that happens at night. Didn't happen when I was there until forcing defrost and getting a E3 HP trip.

BTW defrost started just fine, it had tripped while I went inside to check the indoor fan had stopped like it should have when defrost initiated (it had, and was working fine in heat mode)
When i left the outdoor to check inside, HP to indoor coil was 1000kpa and LP to outdoor was 140kpa, so it seemed to change over OK.

[frank]

Why do you need it on heating when the ambient is 19C?

There is a limit of 23C ambient I believe when heating will be inhibited.

Is your outdoor air sensor reading above 23C when it cuts out?

[Dunno_Daikin]

I was attempting to repair it. I don't live there, it cuts out for them at night.

Yeah I know all about their won't heat but certain ambients, which is why daikins infuriate me more than any other brand, hard to diagnose when I only work during the day.

I did say the ambient at the time was 19C.
Doesn't explain the e3 cut out though on forced defrost though.

[Ross]

Hi mate.

Don't know if this is alittle of topic but I will explain abit of history of the RY series Daikin as I worked as a Tech for Daikin 10yrs ago when at the time they were the current models.

The RY series outdoor units was manufactured in Japan to be matched with a Japanese indoor however in Australia the indoor units were manufactured in Sydney to suite Australia conditions and larger homes. They therefore have a slightly larger coil than the Japanese one. You will find that on start-up that the outdoor fans will be delayed from starting by up to 5mins. This was due to the unit not wanting to raise the HP to rapidly in heating mode with the Japanese indoor. This is not so much of a concern with the Australian indoor.

You will also find that when the outdoor fan starts that only one operates. Can't remember which (top or bottom) but this was again not wanting the HP to raise rapidly or too high. This also creates issues with frequent defrost due to high RH is the air especially is temperatures above 0deg C.

A common practice was to connect the 2 outdoor fans together off the 1 PCB output to operate together. By doing this you should achieve better temperatures inside and have less defrosts during the night.

Hope this info helps.

[Dunno_Daikin]

Thanks for the background info.

All three times I tried to test this unit (19C ambient), no fans for 5min, then both came on at the same time.
Historically with other daikins giving me this same problems (ry125 or ry150) on ambients around 15-20C on heat, it's been fan related and LP problems as they too stay off for 5min and the LP may trip out or the compressor slug liquid because of this 5 min fan delay.
I'm not sure what the problem with this one is though, as they say it cuts out and blows cold air. I don't know if a LP problem runs the indoor on fan only on an LP fault when in heat mode?
This unit definitely did that though when it triggered a HP fault after defrost started (and again not running the outdoor fans for 5min tripped the HP fault).

[Dunno_Daikin]

RY250 I meant, not ry150

[Dunno_Daikin]

This particular unit is a ry125, just meant I've had LP problems with ry250s in the past

[superjebb]

sounds like a blockage in the condenser or the revering valve isnt moving accross properly! worth a look!

[install monkey]

panasonic urban units cu250-same as ry250- matsu****a- r407c twin fan in heating mode on a low ambient - left had fan wouldnt work then after a light frosting on the outdoor-usually after 5 mins the right hand fan would kick in- i tested the thermistors,pipe and coil all ok in range, desoldered the lil relay on the board as the fans do have 2 speeds- in the end i used the live for the left hand fan powered straight off the a1 signal for the compressor contactor so when the comp starts the lh fan starts after a few minutes the rh fan starts -all was well.

[Ross]

It is important to make sure you have suffient airflow across the indoor unit. I had seen many installations where the installer had to much ductwork therefore creating too much static pressure. As a result the airflow was well below the design requirements and causes the indoor coil temperature to rise too high and possible HP faults. This then forces the outdoor fan to cut-out in an attempt to bring the pressures down.

I found by applying the HH field code setting, if I remember correcty 13-02 through the wall controller, instructing the customer to use the high fan speed in heating and if using zone motors to open as many as possible this resulted in far better operation/tempertures and reduced the number of defrosts during the night.

If using circular diffusers ensure they are opened fully to push the hot discharge air down and reduce the amount of stratification of hot air. Some Australian homes can have high ceiling (3m or more) so pushing the warm discharge air down to prevent stratification is extremely important!

Also check the return air sensor location (return air or wall controller).

[Dunno_Daikin]

sounds like a blockage in the condenser or the revering valve isnt moving accross properly! worth a look!
Yeah but the change over was fine, I think I made a mistake in the first post, on heat mode:
HP 1500kPa to indoor
LP 380kPa at outdoor.

On forced defrost 1000kpa to outdoor, and LP to indoor was 140kpa.

I don't know if it chucked a spaz and tripped out because it's to dumb to handle a defrost when it's not frozen up, and tied into some fan delay wizardy. IE because the outdoor coil wasn't defrosted and the fans wouldn't run, after a few minutes the outdoor was high pressure and tripped.
I guess what I need to know is someone who knows daikins to say "ya wally, of course you can't force defrost and not expect it to trip. Of course it won't cancel forced defrost itself based on coil thermistor saying the outdoor coil is warm."
Or someone tell me that "something is very wrong that it sat there in forced defrost with the fans not running and it tripping out in HP rather than starting up the fans or cancelling defrost itself"

Every winter I have problems with older daikins (6-8 years old) pulling stunts like this when it has worked fine for years. Hard to tell people there's well known problems and they've just been lucky, hard for me to know for sure what's going on.
I tend to avoid daikins for that very reason, but every so often I have a long term customer that has used me for every other building and a/c they've had, so I have to take on the problem or lose them as customers I guess. Otherwise I'd be happy to tell them I just plain don't know, call someone else.


panasonic urban units cu250-same as ry250- matsu****a- r407c twin fan in heating mode on a low ambient - left had fan wouldnt work then after a light frosting on the outdoor-usually after 5 mins the right hand fan would kick in- i tested the thermistors,pipe and coil all ok in range, desoldered the lil relay on the board as the fans do have 2 speeds- in the end i used the live for the left hand fan powered straight off the a1 signal for the compressor contactor so when the comp starts the lh fan starts after a few minutes the rh fan starts -all was well.

Interesting theory, problem is I don't know if there's something else wrong with the system and it may play up in some other way so the problem may not be fixed and there's just my bodge job to see for someone else who they call after me failing to fix it...


It is important to make sure you have suffient airflow across the indoor unit. I had seen many installations where the installer had to much ductwork therefore creating too much static pressure. As a result the airflow was well below the design requirements and causes the indoor coil temperature to rise too high and possible HP faults. This then forces the outdoor fan to cut-out in an attempt to bring the pressures down.

I found by applying the HH field code setting, if I remember correcty 13-02 through the wall controller, instructing the customer to use the high fan speed in heating and if using zone motors to open as many as possible this resulted in far better operation/tempertures and reduced the number of defrosts during the night.

If using circular diffusers ensure they are opened fully to push the hot discharge air down and reduce the amount of stratification of hot air. Some Australian homes can have high ceiling (3m or more) so pushing the warm discharge air down to prevent stratification is extremely important!

Also check the return air sensor location (return air or wall controller).
Yeah these are old units, so been working for years. Airflow and all the basics is what i hope to be the cause when first called to these jobs. Most of the time it's not though unfortunately.
I don't know about any daikin parameters though, I have heard of them, but that's all.

[Dunno_Daikin]

Yeah but the change over was fine, I think I made a mistake in the first post, on heat mode:
HP 1500kPa to indoor
LP 380kPa at outdoor.

On forced defrost 1000kpa to outdoor, and LP to indoor was 140kpa.

On forced defrost that is only the initial pressures of course, not the pressures it cut out on.
I couldn't tell you them, because I was inside making sure the indoor fan shut off while in defrost mode. (Cust complaint was cold air blowing while in heat mode)
Indoor fan had indeed shut off during defrost, but a few minute later I went outside to find the unit tripped out of fault.
I went back inside and found the indoor fan now running blowing cold air like the owner described, and the controller showing 'E3', HP cut out.