01-17-13, 03:54 PM | #11 |
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AC,
If the control board made this unit try to work by pressing the test button, and didn't flash the red light, it probably works. This is good for you because you can interface with the brawny parts (relays, contactors, thermistors, etc) directly pretty easily. Interfacing with an arduino would be simple to do. Just throw an addressable switch (DS 2406, DS 2408) in the unit and impose control thru the 1-wire interface. IMHO, this approach would be much easier and cheaper than re-inventing a control board or decoding comms and faking an indoor unit. |
01-18-13, 03:59 AM | #12 |
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Im curious is there any advantage to a non-inverter mini-split without its control? What makes the mini-split any more efficient than say a window unit? Larger coil obviously helps, but what advantage does the multi-speed fan have if the compressor doesn't ramp up and down with it?
In Heat-pump mode it seems to me you would basically want the outdoor fan to run full speed always(beside defrost) to obtain the max amount of heat from the air, and vary the indoor pump speed to maintain adequate head pressure and floor temperature. Actually if that's the case, building your own controls shouldn't be to hard if you can figure out a decent demand defrost algorithm. Best of luck, Adam |
01-18-13, 09:19 AM | #13 | |
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This From Acuario...
This from Acuario in response to questions about controller electronics:
Quote:
Best, -AC
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01-21-13, 04:22 PM | #14 |
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Digging Deeper...
I removed the front panel to allow a closer look at the components...
Here's a look at the whole unit from the front, showing the fan and the compressor. I see that the fan shows a little discoloration, but really, very little. Here is the compressor compartment with all the compressor-related components... This is a closeup of the compressor identification label. The crankcase heating assembly. This is the reversing valve. The transformer for the control board power supply (or maybe it's for the fan?) The starting cap for the compressor that provides a slightly off-phase kick to get the compressor motor going. And lastly, reaching the camera through a small space behind the compressor and pressing the shutter with the bloody knuckle of my thumb, is the cap tube. Best, -AC
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01-21-13, 09:14 PM | #15 |
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That heater coil/spring looks the same as on my Sanyos. It might be controlled by the controller board.
My heaters were traceable back to a relay on the main controller board. When it's warm out, the heater stays off.. I would keep the controller if possible, since it might have a good defrost setup. When you hook up AC power (to 5&6), two of the other terminals should go hot, to power the indoor unit. You could find them with a voltmeter. ~~~ If you have found the 2 power lines, you should find out if one of the low voltage lines is ground. For safety, one one of the lines going inside the house might be ground. If it is ground, that only leaves 1 line left for control. Single line controllers sometimes use a DC bias voltage and the control input is a set of resistive loads. Maybe like this: A. Zero ohms (short) = standby B. 2.3V+ = Cool (medium resistance) C. 5.0V+ = Heat (high resistance) D. No load = Maintenance mode, use test button. If were to find one of the lines had low voltage DC on it, you could try connecting a Pot or variable resistor and turn it's resistances up and down to see if it changed the operating mode..?. The other side of the pot would be connected to ground. But, before I did this, I would do a lot of searching for a schematic diagram. ~~~ If there is no ground, and you have two control lines, one might be compressor ON and the other one would be mode, cool or heat.. Hopefully both these lines would have a low DC voltage on them..
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01-21-13, 10:45 PM | #16 |
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That unit looks clean! Did you notice any dirt in the coils?
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01-22-13, 01:44 AM | #17 |
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Hey AC,
I believe I found your schematic/service manual. From the parts seen in the pics, it looks like your unit is in fact an LG model HMH012KD under the skin. The schematic and service manual is here (rebranded as ICP Commercial): http://icpindexing.toddsit.com/docum...litservice.pdf Happy hunting! Jeff |
01-22-13, 02:07 AM | #18 |
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Well, that schematic corresponds pretty closely with the configuration on that outdoor board.
So I'll eat my words. It uses a one wire serial protocol on terminal 1 of the unit-to-unit link. Having said that, you can quite easily remove the CPU chip and drive all your solenoids from the inputs of IC8 using logic levels, so you don't need to interface to any high voltages. In addition, you have a thermistor connected to the main cpu also which you could connect directly to an arduino or equivalent. Last edited by BradC; 01-22-13 at 02:26 AM.. Reason: Only one thermistor. The other pins are option resistors |
01-22-13, 08:24 AM | #19 |
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Yeah, fooled me. I would not have expected an older non-inverter unit to have serial.
I guess the newer stuff is just a copy of the old stuff.. Pin #1 is a bi-directional control line. So, you not only send commands outdoors, you read back status data too. Seems like it would be simpler to wire your control pair across the test button.. Brute Force Control. Outdoor Once push : Ignore Communication error. Twice push : Comp. ON, / Outdoor Fan ON / Reversing Valve Coil ON(only Heating Model) / Crank Case heater Coil ON(only Heating Model) 3 Times push : Comp. ON, Outdoor Fan ON / Reversing Valve Coil OFF(only Heating Model) / Crank Case Heater Coil OFF(only Heating Model) 4 Times push : Same 5 Times push : Error LED(Red) ON 6 Times push : Comp OFF, Outdoor FAN OFF 7 Times push : Reset That might get you the basic operations you need. If it will stay running in the test mode.. (No time-out). And, you will likely have all protection/defrost functions too..
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01-22-13, 04:00 PM | #20 |
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Mega Thankyou's to Xringer, BradC & jeff5may!
You've provided some interesting info & approaches. The manual looks awfully close to the unit I have. The differences appear to be very small. Geo NR Gee: Nope, the coils are sparkling clean... much cleaner than the fan blades. At this point, I don't have any intention to run the unit in cooling mode, but for the time being, I'll leave the reversing valve where it is. It might be useful to be able to send some of the summer heat into the ground. Anyway, from your info, I'll do some testing & let you know what I'm finding out. BTW, I saw a time-line chart the other day about R22, and it looks like the final phaseout (no more sales of R22) will be a few years from now. So you can expect to see a considerable amount of good HVAC hardware for a song or even free, pretty soon. I was seeing new R22 mini-splits for sale as recently as 3 years ago... in a few years, they'll be unserviceable unless you know a few secrets. Keep your eyes peeled! Best, -AC
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