Fault with Tango cassette

[airefresco]

Got called out on Friday to a Tango cassette system, which runs for 7 minutes and then slows the fan into a super low speed (irrespective of what the fan speed is set for on the controller) for a further two minutes and then goes into fault. There was not a service valve on the suction side at the outdoor unit so I couldn´t take a reading there. Checked and cleaned the filters. At first i suspected a possible fault with the fan, because when it slowed right down the suction line would start to freeze back to the compressor and then the unit would trip.

I wired the fan so it ran in high speed all the time, just to check it was nothing to do with that, and the unit still went in fault after 9 minutes. Although the freezeing didn´t happen.

Went back again yesterday and brazed a 1/4 stub on the suction side. So now i know the gas charge is right and theres nothing wrong there. Disconnect the compressor and ran the unit. Exact same fault occured. Started looking back to the indoor unit. With the compressor disconnected, I disconnected the indoor fan, just to make sure it wasn´t that, still the same fault. Disconnected the drain sensor and the unit tripped straight away. I took the drain pump and sensor out, (which wasn´t easy) and the drain sensor is a design I haven´t seen before. It looks like a coil sensor, but has 4 wires coming out of it (2 black, 2 brown). Across the two of the wires I had 80ohms and open circuit between all the other wires. I put the sensor in some water at various different levels and the result were exact to when the sensor was dry. Tried warming the sensor the up and cooling it down and again, no change in the readings. So i reconnect the sensor and left it hanging in mid air and disconnected the drain pump. Started the unit up and theres 240v to the drain pump.

I think it´s a faulty drain level sensor and the pump is continually running for 9 seven minutes, which causes the unit to go into fault. The thing is, I don´t think I´m going to be able to get a new sensor for it. I think the best thing would be to just rip out the old internal pump and fit a aspen or something, but i need to know how the old sensor works before I can do that. If unplug the sensor the unit goes straight into fault.

I don´t believe it´s possible to get fault codes from the indoor unit with these units, but maybe someone can prove me wrong here? You can get faults from the outdoor unit, but that doesn´t show a fault, so I think thats only for faults on the outdoor unit. If i knew how the sensor worked, i could make something to fool the indoor unit into thinking the drip tray was empty and use a external pump to get rid of the condensate water.

I would be most grateful if anybody could help me with the sensor issue or spot something that i might have missed.

The model of the in indoor unit is Tango, KFR-112Q/A (theres a second number on the data plate also, KFR-112QW/SA). Gas is R22.

Many thanks
Paul.

[Brian_UK]

I don't know the Tango unit so this is just a few thoughts.

The drain sensor when disconnected will set the unit into fault mode on most makes.

The four wires are probably two for the heater and two for the sensor.

The sensor is heated and the temperature monitored by the system. When the water level rises and covers the sensor then the temperature drops, the sensor is read by the software and starts the pump.

When the water level drops the sensor is exposed and its temperature rises again.

I suppose if you could find out the correct resistances then you could hard wire a fixed resister to simulate a 'no water' condition and then add a separate pump set.

Good luck with it.

[frank]

I suppose if you could find out the correct resistances then you could hard wire a fixed resister to simulate a 'no water' condition and then add a separate pump set.

You could also use a rotary 'pot' resistor which will allow you to trim until the correct value is found.

[airefresco]

Thanks for the replies.

I think a resistor is the way to go. As Frank said a variable resistor would do the job for now to find the correct resistance. I´ve attached the relevant part from the wiring diagram on the indoor unit. So from this assume 1 and 2 are the heater and 3 and 4 are sensor?

If I connect a pot to 3 and 4 and leave the heater disconnected, then that should work?

Thanks
Paul

[VRVForever]

Dont worry yourself about this you wait til the doctor Pepper one comes out shortly. However it is approved by a doctor.

[Brian_UK]

..........If I connect a pot to 3 and 4 and leave the heater disconnected, then that should work?

Yep, it should do the job.

[airefresco]

Thanks, I'll have a go and let you know how I get on

[momo]

With the problems and parts you're describing I wonder if there are low voltage contacts or a DAC on the control board that's faulty.

I really wonder who designs that make.

They seem to me to be like end of engineering course projects complicating what can be simple and standard !
Yet their remotes seem like some Midea, Daitsu and Carrier cheapies !
Horses from the same stable again.
Any additions to this detectives game?
OR
Can somebody admit being an engineer or serviceman for them (or know one)

Hendrag did so for LG (well done)...and the manufacturer acheived a degree of credibility with his instructions and help...
TAKE NOTE OUT THERE IF YOU WANT TO SELL TO PROFESSIONALS.

[airefresco]

I did a search on the internet for the model number and came up with only one company that made cassettes with the same model, China Clime Electric Appliance Co., Ltd.

I believe that Grupo Disco, put the Tango badges on the units, but i'm not 100% on this.