General 07LCC

[aircon50]

Hi all. I have a General ASHA/AOHR07LCC that is displaying a Serial signal error.
Operation LED - off, Timer LED - 2flash, Coil dry LED - off.
This equates to Serial signal (reverse) error, at operation start up.

I have conflicting ideas as to where the problem could be. I have been told that it could be external PCB and/or external fan motor.
However, I have no voltage on terminal 1 & 2 at interior or exterior units. This would indicate that the problem could be with the interior PCB.

Can anyone confirm, please?

Thanks, Graham

[Tayters]

System is indoor power supply. When the outdoor needs to run a relay on indoors closes and you get power to outdoor and comms initates between units. If the indoor gets no response then the relay turns off and fault code flashes up.
You need to reset the power to get comms/power initated again.

Common error is that something outdoors takes to much current on start up and outdoor PCB shuts down via a thermal gizmo to protect itself.

You need to confirm outdoor fuses intact (2 on PCB, one in a fuseholder from the terminal block), try unplugging all all components and run up to see if PCB now communicates. If no comms but voltage from indoors then looks like outdoor PCB is man down, then you need to check if one of the plugged in parts have caused the damage. Check compressor and fan motor to earth with megger, fan motor is a normal PSC jobbie, EEV 46 ohms on red-orange, red-white, brown-blue, brown-yellow, 4wv coil about 1.3k ohm, none of these wires and also wires to probes not shorting to earth.
If you get comms with just the PCB then looks like something you've unplugged is taking PCB down which the component checks should root out.
If a fuse has gone then need to follow the circuit to see what has taking it out.

Make sure that the PCB has all the screws to the heat sink. If missing you normally get an inverter error code but worth just taking a note while you are there.

Don't forget to confirm continuity of interconnect and outdoor isolator if fitted no corrosion/loose wires.

Emmanuel: http://masterxoloda.ru/files/fujitsu_general/asha07lcc_0602g3038.pdf

Cheers,
Andy.

[aircon50]

Hi Andy

Thanks once again. I'll go back and look it over again and let you know the outcome.

Best regards
Graham

[aircon50]

Hi Andy. I've been back for another check.
With all components disconnected from the external PCB, the interior relay energises and I have voltage at the exterior unit, but only for a short time until the error code is re-generated.
Compressor and fan motor meggered and ok. Compressor windings approx 0.70 ohms each. Fan motor Orange -White 23.9 ohms, Orange - Black 43 ohms and Black - White 190.6 ohms. Choke approx 0.4 ohms.
My gut feeling is external PCB - but reluctant to order replacement until I'm sure!
What are your thoughts?
Cheers, Graham

[Tayters]

Hi Graham,

Fan motor resistances don't add up but this shouldn't cause PCB error...
Are the 2 fuses on the PCB intact?
Do you have 300ish VDC on across the P and N of inverter IC? If yes then one fuse is fine.
Unplug a probe, power up and with power to outdoors should get 5V DC across connector - this proves other fuse fine and more than likely comms IC has power.

Disconnect comms wire at indoor, power up and get power to outdoor, check voltage between N and 3 of indoor to prove indoor comms and N and the now loose wire to confirm comms from outdoor. Memory gone blank, been a long day, but try your meter on AC and DC, should get fluctuating 50V on one of those scales.
Got a couple of mins before indoor flags up comms error and shuts down.

Did the link work? Just tried it and found had to copy link into address bar, clicking on link didn't work. This is handy for checking the points on the PCB.

Yes, looks like PCB outdoors but could do with a bit more checking to confirm. Also interconnect alright?

Cheers,
Andy.

PS Happy New Year!

[Tayters]

Just thought, did you power board up with choke disconnected? You'll need this component in so it can power up.