Daikin H3P on Outdoor Units

[Chris2005]

Hi All

I was called out last night to 3 comfort inverter daikin cassette units, 1 indoor BRC1D52 controller controls all

The 3 outdoor units all had the H3P led on constant but all the units were still running but the compressor were running slow and no heat

I checked the controller and pressed the test button once and it displayed unit 0 U0

Pressed test again and it displayed 2 J6

Third press shown FA

Because of the U0 fault I reclaimed the refrigerant from them all and recharged using scales

two of them only had 1.8 kgs instead of the 3.7 ( no leaks found but service caps were loose )

After the recharge the units work great for about ten minutes then all units start to go slow even though the shop is cold , they keep running like this for some time producing no heat, fans running full speed compressor just ticking over.

Is there anyway to check the codes on the outdoor units as I'm not sure if 1 fault is shutting them all down or should they operate as normal when on the same indoor controller even if one has a fault

The indoor controller only seems to show unit 0 and I'm not sure how to check the faults on the other units, if each outdoor unit would show its error code it would be easier

[frank]

What are the model numbers?

The fault codes you were seeing were 'old' faults. Any current faults would result in a flashing operation LED on the BRC controller.

Have you put them through a self test routine?

[Chris2005]

Hi Frank

Model number RZQS125D7V1B

No flashing lights on the controller just the H3P lights on constant on the outdoor units

Ran through a test mode and no flashing light on the controller

Even though the shop is cold the outdoor unit compressor are running slow and providing no heat

if the units are turned off and on they rev up and provide good heat for about ten minutes then the H3P LED comes on again, no LED flashing on indoor controller

All 3 units have had the main outdoor PCBs changed over the last few years because the fan motors went faulty and damaged them ( 2 were changed 2 years ago, the other 6 months ago )

[jzmalta]

i would try to operate them individually, by eliminating the control cables from the remote and connect only one unit each time. might be a problem from an indoor temperature sensor.

[frank]

There are a number of reasons why the system is operating as you describe.

With no flashing led on the BRC controller, you do not have a current error/fault.

The BRC controlling all 3 indoor units does not have any incidence wuth the operating conditions, it is only 'telling' the individual systems to achieve a certain condition ( heat/cool/setpoint etc.).

Each system will operate (or not) individually. 1 system cannot affect the other 2 systems.

In heating mode, the indoor unit is effectively your condenser. If there is a restricted airflow across the condenser, then the head pressure will increase and the system will back off to compensate. Make sure that you have really good clean filters on the indoor fancoils.

Do you know how to interrogate the BRC controller to view the indoor sensor readings? This will allow you to read the 'Suction Temp' (return air) Heat Exchanger temp and Liquid temp.

There are a number of senarios where the system will back off the compressor for self protection, see section 3 of the linked manual. https://www.manualslib.com/manual/12...page=51#manual

Do you know if there are any settings applied to the BRC that distract from the factory defaults?

It is difficult to diagnose from afar, but if all 3 systems are behaving the same, then there may be a setting in the BRC that is causing it. As jzmalta suggests, try disconnecting the current BRC and run each unit individually.

[Chris2005]

I went back to the shop this evening to see if I could find out more information

If all outdoor units are turned off and on again the units run OK for 15 minutes providing good heat

after 15mins the compressor slows ( no more heat ) on all units and the H3P LED illuminates on them all a few minutes apart

I have tried each outdoor unit one by one and left the other two turned of at the power supply, the results are exactly the same for each

unit runs for 15 minutes fine then slows down and the pipes to the indoor unit are barley warm, few minutes later H3P light ( I timed each unit and they are behaving the same way )

No fault codes displayed on the BRC


I also tried the 3 outdoor units in emergency heat mode using the dip switches but it made no difference


" Do you know how to interrogate the BRC controller to view the indoor sensor readings?" I dont know how to do this from the BRC

Is it possible the outdoor units need to be setup after having new PCBs fitted ?

Its possible somebody else has altered the BRC from factory but I'm not sure

shop was to busy this evening to check the BRC on each unit

[martinw58]

have you checked the temperature sensors are correct unit might think it warmer than it is

[Chris2005]

Do you know where I can get the data for the sensors so I can check there resistance ?

I found out today that they have not been honest about the problem, one of the staff told me that 2 of the units went off some time ago, I was led to believe they went off at the same time.

[frank]

To view the sensor readings on the BRC1D52 press and hold the bottom left engineer/test button for more than 4 seconds until the display changes. Then let go and repeat until the display shows '40'

Now use the Temp Up button once to change to '41'

The display will now show 00 at the top and a larger 2 digit number. The 00 relates to the sensor in the controller and the larger 2 digit number is the actual temperature reading.

Using the Timer button, press once until the 00 changes to 01. This shows the temperature of air being drawn into the fan coil.

Pressing the Timer once more changes the display to 02. This shows the temperature of the Liquid line.

03 shows the temperature of the Suction Gas temperature.

See page 27 of the Service Manual http://www.daikintech.co.uk/Data/Spl...S-C7V1B_SM.pdf

The field Settings are on page 92

Lots of info on Youtube - search BRC1D