Daikin Split PCB Relays MRM20 & MRC/W1 coil protection diodes D10 and D5

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My Daikin Outdoor unit Model Number RXD60JVEA is displaying a U2 fault (Main circuit Overvoltage or Lowvoltage). Instead of replacing the whole PCB at extraordinary cost, I thought I would give my electronic fault finding a go. I suspected relays MRM20 and MRC/W1 (P/N Omron G5N-1A 12VDC) on PCB (P/N 2P059475-1) weren't energising when the A/C was selected on, and therefore there is no fan or compressor operation. So I removed the relays from the PCB and placed a 12VDC source across the coil and checked continuity across the switch. All good. I then decided to remove the diodes that are in parallel to the relay coils and found one of the diodes shorted (D10). I believe this is my problem. My dilemma is that they are a very small glass diode with only a Yellow and Silver band around them with no other identification markings. I have rung Daikin Australia for technical support but even they don't get given details of PCB individual components.
My question is, does anyone know of the part number or equivalant? And secondly, if I was to run the air conditioner without the diode, would it make any difference?
Any suggestions would be appreciated. Cheers