View Full Version : DIY 'Air Force' Split System Wiring.

11-07-2012, 10:33 PM
I got a cheap split system off of ebay from a bloke who couldnt get planning permission for the outside unit. I am a plumber by trade but am building a recording studio as im sick of the trade now. I have fitted the units in place and connected the pipework but the electrical connections are a little confusing. (there are no instructions with it)

I would have loved to have bought a better system but the Divorce left me with very little so im doing it the budget way until i can afford to improve it.

From the indoor unit, I have a large multi plug with large blue, small blue, large brown, small brown and earth, and a small plug with red & Black cables. The outdoor unit has screw terminals for Live, Neutral and earth and a small plug with yellow and brown wires but this does not fit the small connector from the indoor unit.

Im assuming that the smaller wires are control wires and the blues and browns in the big plug can just be wired into the terminals but i just though id ask the question here to see if anyone has a definitive answer on this before I weld myself to the ladder.


Andy AC
11-07-2012, 10:45 PM
Looks like you have been sold a mismatched indoor aand outdoor unit. If they were right, the plugs would match.

11-07-2012, 11:00 PM
Yes, I already figured then when i googled the part numbers,
Indoor unit- MUB12HRN1-QC Outdoor KFR-35w/NaB20-J I think i have been had by the seller on ebay. The pipework connected no problem so im just hoping that its simply a case of cutting off the connectors and connecting the wires on the correct terminals :/

install monkey
11-07-2012, 11:27 PM
if u ring b&q technical then youll get no joy- best thing to do is try it-as the indoor pcb should be fused- was gonna say get the mrs to switch it on- but plan b- switch it on with a stick

12-07-2012, 08:23 AM
I take it that the small brown and blue wires are likely to be 240v live and neutral or surely they would have used different colours! i will dismount the ladder and stand clear when i press the loud button!

12-07-2012, 10:23 AM
Can you post a picture of the wiring diagram? - normally found on the inside of the electrical cover outdoors and inside the fan cover on the indoors

12-07-2012, 03:40 PM
The external unit 1 =n 2 =L Yellow wire =terminal 3 (fan neutral) Brown wire = fan live.
There is no diagram on the internal unit... :-( I wired the large brown, blue and earth into the main terminals and the small blue to the yellow, small brown to small brown... Switched it on and I get a red light flashing on indoor unit 'def./fan' could this be something to do with the small connector (red and black wires) coming from indoor unit which don't connect to anything?

12-07-2012, 08:32 PM
I'm not familiar with the make or model as we tend to stick with main stream makes, that's why I asked for the diagrams.
With the wiring diagram, I could answer your question.........

monkey spanners
12-07-2012, 08:53 PM
Some of them wires are a thermistor (low voltage temp sensor) they will not like having 240v shoved up em.

Imagine a customer has bought a toilet bowl and a sink and is trying to make it flush by plumbing the sink into the toilet, is like that only with air con.

Also, its illeagal for you to be working on this without having a current F-Gas cert....

install monkey
12-07-2012, 09:00 PM
john its an airforce- all u have to do is go b and q and pick 1 up- usually upside down on the racking, at the check out they dont ask for f gas quals- just would you like a store card.
aeroquip flexi lines - idiot proof-until the o rings perish- gaurenteed to fail- in this instance same scenario but the dude has been shafted by his misses and an e bay seller- so he's only mauling with the wiring- who knows it may not have any gas in as it was a mismatch- id get on e bay and stick it though his f**king front window if he doesnt replace it

12-07-2012, 09:34 PM
I've found the correct indoor unit (again on eBay) (gulp!) though I have spoken to the seller and he appears to speak English! Like I said, it's only to get the place up and running, I'll getting a proper system as soon as the money is coming in!

The Viking
12-07-2012, 11:12 PM
And this is for a recording studio?

Having worked in that environment in the past what you need is an over sized ducted unit with proper attenuators in the ductwork, all designed to operate on minimum fan speed with low velocities in the duct.

This unit of yours was cheap and what you could afford?
Sorry to tell you but what you really bought is the most expensive paper weight or shelf you ever seen. If you get it up and running it will be to noisy for the environment you are creating.

Your best option until you can afford the ducted system I mentioned above would be fresh air, again with attenuators and low velocity in the ductwork, supplied where people is likely to be and extracted above the equipment generating heat.