Airforce Air Conditioner - Error E6

[Road_Runner]

Hello All,
I have a split air conditioner which has just decided to stop working. It had worked the day before. The unit was marketed as Airforce, model number GWHD12B2NK3AB as sold by B&Q several years ago.
The outdoor unit circuit board is a GREE, board number GRJW9M-A1 V2.31.
What I am interested in knowing is the method of data communication between indoor and outdoor unit. Is it a pulsed voltage or a standard protocol? The signal is received by a set of opto-isolators on the outside board and then sent to the microprocessor on that board. I would guess that information from the outside unit is sent to the indoor unit in an identical manner.
Any advice on the communication protocol would be gratefully received.
Regards

[install monkey]

e6 - When outdoor unit is energized and fails to receive data of indoor unit within 30 seconds, an indoor unit communication fault is
reported. The compressor and the outdoor unit will be shut off,
and the four way valve will be stopped 2 minutes after the
compressor outage in heating state.
If indoor unit fails to receive information of outdoor unit, a
communication fault is reported. The indoor unit is shut off and
an indicator is twinkling. If the display board fails to receive
information of outdoor unit, a communication fault is determined
and displayed and the machine does not actuate. After
communication becomes normal, the system can restore to the
previous running state itself.

[install monkey]

http://planetaklimata.com.ua/instr/Gree/Gree_U-Match_Service_manual_Eng.pdf
source via a gree manual

[Road_Runner]

Hello Install-Monkey,
Many thanks for your kind replies. I have taken a look at the pdf and I believe that the communication is as described in it. It's the protocol I am interested in such as whether it's RS232, RS458, Modbus or such like so that I can check that both the indoor and outdoor units are attempting to communication with each other. I know that the data communication is between the COM and Neutral line and I have the equipment to monitor the line safely to check.
Kind regards
Paul

[Tayters]

Hi Paul,
Normally with splits the 240 AC signal is used as a king of carrier signal. The outdoor will pulse the positive half to build up a binary signal and the indoor looks at this half whilst using the negative half for it's time to communicate which is what the outdoor is looking for. Might have got those the wrong way round but that's the concept anyhow.

It doesn't matter if the pulse is on a lower or high part of the sine wave as the opposite unit is just looking for a + or - set of pulses. The actual language which is used seems to be a closely guarded secret which only the designers seem privy to. Don't think it will be any standard lingo. Manufacturers bring out a new system and it's incompatible with the old gear so I guess that tells the you the protocol would be different. You can hook up an oscilloscope to see what it looks like. Otherwise disconnect the comms wire, power up and see if you get a DC voltage from each unit. One will be +, the other - varying from 0 to 80 odd volts. After a while you will get a comms error then comms is stopped hence powering up to initiate comms to begin with.

Some makes do it in a different way. MHI and I think Mitsi Electric units for example have a 20V comms signal so not sure what's going on there...
If you have an EEV outside then a good idea is to see if the valve initialises on power up which tells you the outdoor unit powers up enough to set itself up therefore comms from this unit probably alright. Yours might not have an EEV but I think it's an inverter so there may be a few voltage measurements around the PCB you could take, 5V DC across an unplugged probe is a good start. Comms wiring, neutral wiring, high level pump switches if fitted are other bits to have a looks at.

Cheers and Beep Beep. :-)
Andy.

Edit: Found wiring diagram: http://www.lomax.dk/brochurer/Brugsvejledning.pdf

[install monkey]

mhi have outdoor eev's 2 of em- with the hard wired controller you can see the valve position

[Road_Runner]

Hi Paul,
Normally with splits the 240 AC signal is used as a king of carrier signal. The outdoor will pulse the positive half to build up a binary signal and the indoor looks at this half whilst using the negative half for it's time to communicate which is what the outdoor is looking for.

Hello Tayters
Many thanks for your comprehensive reply and safety warning. I have many years experience in electronic servicing so I will be taking safety extremely seriously. My interest in only in checking to see if it is a comms fault due to electronic component failure which will be serviceable. Should the fault be elsewhere then I guess I will be replacing the system.
Your response is gratefully received.
Kind regards
Paul

[Road_Runner]

Hello,
Please could anyone advise me what the opto-isolator part numbers are for IC01 & IC02 on the outside board. I can only partially read the part number (PC8??) but cannot make out the full numbers since they are very feint.
Many thanks
Paul
11850

[Road_Runner]

Hi,
I may have traced the fault to a metal oxide resistor “R4” on the internal circuit board whose colour banding does not appear to match the measured value. It looks like a 210 ohm but measures 22K.
Could anyone tell me what the value should be or can tell me the colour bands.

R4 is the large resistor below D5

Airforce GWHD12B2NK3AB
Rated power 1600/1650watts
Cooling capacity 3500w
Heating capacity 3900w
Refrigerant R 410A
Internal circuit board GRJ9Q-A V1.1

Regards
Paul

11872