Inverter Help!

[aircon50]

Hi all. Please, I need some assistance with an inverter unit that has been dragging on for months! I don't know the full history, because I have been asked to assist the company that has been involved so far.
Exterior unit - General AOH18LMAK2 Interiors - 2 x ASHA12LACM.
History as far as I can tell - Units running, but one system not cooling - both EEV's replaced. Has not run since!
Main PCB, 1200uF capacitor, ACTPM have all been replaced.
There are no error codes on either interior units, or on exterior unit. However when CN21, CN22 and CN23 are disconnected the relevant error codes are generated. When CN39 is disconnected multiple codes are generated as expected. When CN37 and CN38 are disconnected no codes are generated. Don't know why - does the compressor need to be running?

Readings so far;
Main PCB TM104 - TM105 = 318vDC
W11 - W10 = 290vDC
CN407 1 - 2 = 17.88vDC
2 - 4 = 17.88vDC
2 - 3 = 17.88vDC
1 - 4 = 0
3 - 4 = 0
ACTPM P - N1 = 318vDC
Pos - Neg = 290vDC
L1 - L2 =0.0006vDC
Choke resistance = 0.1 Ohm

I have a EDC test tool and have data flow on both communication connections.

Any ideas??
Thanks, Graham :confused:

[Tayters]

Sounds like you have power to each side as you have no comms errors and codes can be generated if probes unplugged.
Fan motor is a normal PSC so no high jinks there.

Does the outdoor fan start spinning to indicate the outdoor is firing up to do something?

Is everything plugged in where it should be?

Is main PCB screwed down and check IPM is screwed to heat sink. Look for 2 screws on bottom left hand side which each go through a hole in PCB, through IPM to heat sink. If these are left out then IPM can overheat in 10 mins, mind you, normally get fault code. There is another screw top left securing a diode bridge to the heat sink, check this is also in.

Look for any burnt bits on PCB. Might have to pull it out to check.

Unplug a probe, should be 5V DC across pins on PCB - will prove PCB has at least this voltage so other low voltage should be there. Must be there anyhow as no comms error.

Do EEV's click round after power reset?

Outdoor LED flashing any codes an does this also indicate same faults if probe unplugged?

Any inverter output: http://www.refrigeration-engineer.com/forums/showthread.php?37273-Inverter-Testing&highlight=

Two 12's off the 18 outdoor should be fine. If over capacity then you'll get error code anyway.

Will email manual to you. Handy to confirm wiring and what bits on PCB do/go to/what voltage.

Can't think of anything else but all that lot means I need a little lie down now anyhow. Hope it helps!

Cheers,
Andy.

[FreezerGeezer]

I had a weird problem on a Fujitsu a little while ago.
The original installer had changed the EEV motor head / coil or whole assembly, I don't know. Either way, the thing wouldn't hear or cool.
We got called in as the local warranty agent after the installer gave up.
Long story short, Fuji & I decided to replace the O/D cards (Amongst other things, there was no noise at all from the EEV on power up). What I eventually found after that didn't work was that the plank who'd 'fixed' the EEV hadn't got the motor head / coil properly fixed onto the EEV! Once I'd pushed it on properly, no more problem. :)

You said it doesn't work since the EEV's were replaced. I think it is worth checking that the coils are correctly mounted & the EEV's operate correctly.

[aircon50]

Hi guys. Thanks for your responses.

First - Andy. Thanks for the manual - but I do have that one! I've had experience with electronics, and all components that require heat sinking are secured. No burnt bits on PCB - it's a new one, as is ACTPM and capacitor.
As original post, I get error codes generated when sensors disconnected. However, no error codes when HP switch or compressor temperature sensor disconnected.
Everything is plugged in where it should, and fan does not start. EEV's click at power-up as they go through setting. I have your Inverter test sheet, and I've now got an EDC inverter tool. It's handy for checking comms.
Sorry if I bombarded you with too much info! Hope you have recovered after your lie down.......

Freezer Geezer. Thanks for the comment regarding EEV coils. They are secure, and they click on power-up.

Any more info would be greatly appreciated

Graham

[Onsyi]

As I understand it, the power module (transistor) is not verified?
I have it on inverters always check first.
Put multimert mode beep. And check contacts:
P -> U (V, W)
P <- U (V, W)
N -> U (V, W)
N <- U (V, W)
The result should be the same.

[Tayters]

If you select heating does the 4WV energise?
5VDC across HP switch pins on PCB when plug off?
Probes indoor/outdoor read correct resistance?
No wires rubbed through and shorting to earth?

Page 11 of manual, seen HP and comp sensor share the same power supply? Somewhere to look at perhaps?
Are the HP and comp sensor both short circuit when unplugged as per diagram?

[aircon50]

Andy - reversing valve does not energise when heating selected.
Both HP and comp sensor are closed circuit when disconnected. Have not checked voltage at the connectors.
Is there a table of resistances for the sensors available? Even if a sensor had an incorrect resistance would that prevent start-up?
All wires in good condition.
Could the main PCB (new and never run) be at fault?
Onsyi - ACTPM is new. Compressor windings are equal resistance.

Thanks again - keep digging for me - please!

Graham

[Onsyi]

Compressor windings are equal resistance.
Resistance trifle.
Inductance is important!