Can anyone explain this please ?

[fridge doctor]

Hi guys,

I've been to a medium size single phase wall split today (General Electric). Indoor unit makes all the right noises etc. Outdoor unit does nothing. After the usual checks I was thinking indoor board not sending signal, because at the outdoor terminal board I only had Neutral and One Live which was to the coil on the compressor contactor. So back inside I checked the terminals going outside. Found I had Neutral and Four lives at 230v. Double check, yes definitely only one live outside at the isolator.

Pulled the front of the indoor away from the wall and found the flexible cable is terminated with connector strip into a SWA cable of 7 cores (one spare). The other end of which is in the isolator.

I checked the connector strip, it is clean, dry, rust free, tight, wires are bright and shiny. Disconnected from isolator applied power, same as before - only one live out of 4. Disconnected two of the 'missing lives' and connected them together looking for continuity at the other end - nothing ! But this is a 2 metre run of SWA which has been encased in a concrete wall and is just 2 years old. Everything points to 3 broken wires but it just can't be possible.... Oh yes, one other thing, when I flipped it from heat to cool, one of the other terminals did become live, but the original one went to 0v. So let's say number 2 had been live at the outdoor, and 3,4,5 were dead. Then 3 became live and 2,4,5 were dead even though as I said I have 2,3,4,5 all showing live exiting the indoor unit !!

I am certain the terminal ends are making good contact in all cases, and I think it virtually impossible for there to be a break in the cable, can anyone offer any ideas please ?

Wit's end

[Gary]

Did you check the voltage at the contactor coil?

[The Viking]

Back to basics....

Did you check the voltages by the indoor unit with the cables removed?

Did you test the cable (including isolators, terminal strip and so on) for continuity and insulation?

If the above turned out all right, did you run a temporary cable (or 2) to see if it worked any better?

Good Luck

[paul_h]

First some questions.
Is this a unit that receives mains to the outdoor, which then feeds the indoor? Or is it a unit that has mains to the indoor, and the outdoor only goes live when it's cooling/heating?

Is this a unit with a dumb outdoor (no controls/pcbs) and a single 240v feed from the indoor to each outdoor function? ie. indoor feeds the outdoor terminal 1. 240v for compressor, terminal 2. 240v for fan high, terminal 3. 240v for fan low, terminal 4. 240v for reversing valve.
How are you measuring that voltage, to neutral or earth? you could just have a dodgy neutral.

some answers.
If it's a dumb outdoor unit with no controls, i'd disconnect the wiring at your indoor unit. Work out which terminal feeds what (ie 3 = comp, 4 = fan 5 = r/v).
If they're there at the indoor, then interconnecting wiring has to take the blame if it's a dumb outdoor unit.
I usally carry a roll of building cabling to rewire and test for these cases.

If it's got an outdoor PCB then it could be switching neutrals in the indoor unit control PCB. ie panasonics will send out 240v to the outdoor, but nothing happens until the indoor unit switches the relay to give it a neutral.

[TRASH101]

Is there absolutely nothing happening at the outdoor?

If this is true sounds like you have got a neutral fault (open circuit that is) as well as your interconnecting nightmare.

Me personaly would turn it off continuity test the neutral from source then new cable for the interconnecting (if feasable). I guess you have checked all components are good in the outdoor.

[fridge doctor]

Thanks for the replies,

Gary, the voltage at the contactor coil is 240, and the contactor pulls in just fine.

Paul, unit is mains to indoor and then out to 'dumb' outdoor. The neutral is good all the way.

Trash101, The only thing that happens outside is the contactor pulling in.

Viking, continuity through terminals and isolator good.

Back to site in a few hours to run a temporary cable and see what happens.

Thanks

[paul_h]

Wait, you said the outdoor does nothing.
But the contactor gets 240v and pulls in?
None of this makes sense to me.

Any unit with a contactor in the outdoor unit, always has the mains to the outdoor unit.

Usually the compressor runs straight of the mains and the indoor unit 240v for the compressor run signal is just a small relay that feeds the contactor.
If the contactor pulls in, is there any voltage to the contactor switch, in or out?
I stand to be corrected, but why have a contactor in an outdoor unit if mains doesn't go to the outdoor unit first? As te indoor would then have to switch the supply and the control at the same time.

[Gary]

Wait, you said the outdoor does nothing.
But the contactor gets 240v and pulls in?
None of this makes sense to me.

Any unit with a contactor in the outdoor unit, always has the mains to the outdoor unit.

Usually the compressor runs straight of the mains and the indoor unit 240v for the compressor run signal is just a small relay that feeds the contactor.
If the contactor pulls in, is there any voltage to the contactor switch, in or out?
I stand to be corrected, but why have a contactor in an outdoor unit if mains doesn't go to the outdoor unit first? As te indoor would then have to switch the supply and the control at the same time.

Exactly so.

If the contactor is pulled in, the compressor should be running. Trace the wiring from the line side of the contactor back to its power supply. You will probably find a tripped breaker or blown fuse.

[fridge doctor]

OK Guys, pleased to report a happy ending.

Don't want to bore you, but there may be a useful bit to take on board here.

After performing several more tests including the disconnection of both ends of the multi-core and continuity testing, they all checked out OK !

Moved on and decided to bypass the outdoor isolator. Made diagrams and marked everything preparing to rip it out, then I noticed from my previous notes a discrepancy. Basically, the indoor unit has terminals 1 and 2 down as Live and Neutral.
Incredibly though, on the outdoor unit 1 is N and 2 is Live, the other way around !!!

The original installer had obviously not realised, and given up when it didn't work - He would get away with that because it was a new build, unoccupied at the time.

So, General Electric (common in USA I suspect), beware of this possible anomaly.

Thanks again for all your input.

Trevor