View Full Version : Help Needed with Inverter Heat Pump

Not Too Hot
13-12-2014, 12:46 PM
Hi All,

I posted a question regarding a Chinese 12kBtu split system inverter heat pump a couple of months ago which after approx 10 minutes of trying to start up comes up with error code F6 on the inside unit.

Since then I have done some investigating, disconnecting each thermister in turn on the outside unit (all 4 of them) and getting error codes of F0, F1, F2 and F3 in turn so they seem ok.

From the low voltage control board to the IPM board I have +5v, +8v and +12v all spot on.
There is a wire RST which I assume is reset, which changes state when I switch from standby to on.

There is a TX and an RX, again I assume one is transmit (data) and the other is Receive, both seem to have activity (but need to look with a scope to get a better idea), don't know which way data flows.

One I don't understand is SLK, what is that? - any help would be appreciated.

Mains voltage into unit is 245vac which is rectified, then goes to PFC board which gives an output of 367v dc for the motor drive. (just rectifying and smoothing 245vac should only give around 345v dc) so I think the PFC board is working. Can anyone tell me what voltage is normally used on inverter aircon motors as I am not into this line of work - just thrown in at the deep end when my own home unit went Belly-Up!

PFC also gives 300v dc onto the IPM board which seems to power a switching psu to generate 15v dc for the Fairchild IPM chip and also feeds it back to the PFC, possibly for the power supply for the switcher IC.

If you have read this far then thanks for your time - any suggestions (but not rude ones please) or ideas would be most welcome as I do not want to scrap it when I know it can't be much.

P.S. I splashed out on a new Fairchild IPM chip and carefully soldered that in, all to no joy.

install monkey
30-12-2014, 03:57 PM
checked chigo,shinco,kfr and tried matching the error codes youve had with unplugging the outdoor sensors therefore its either an indoor sensor, usually coil sensor or compressor overcurrent- as youve tested the dc circuit, try disconnecting the leads to the compressor and testing the ac voltage accross 2 pins red- white red to black see if youre getting an even output-
try the indoor sensors first

The Viking
31-12-2014, 02:06 AM

Lots of electronic testing carried out...
Your best bet would be to enlist an experienced AC engineer.

Normal faultfinding routes goes something like;
1. Is the power supply present and correct?
2. Is there refrigerant in the circuit?
3. Is the compressor sound?
4. Are all the sensors' resistances within expected ranges?
5. Is the water flow present and correct?
6. Does it operate in test mode?

Only after the above been tested would I start to look at electronics...