Hitachi dc scroll failure

[Jimbo!]

Hi All

I have a Hitachi RAC 2.5kW split that has been steadily reducing in capacity and now won't heat at all. Guages show reasonable static pressure for the temperature but very little rise in heating mode. Compressor is running (sound is normal and quiet) and can hear the inverter ramping up it's speed OK.

Most likely it's dead and uneconomic to repair but I wondered what kind of failure this has experienced?

Probably relevant - when new the system needed to be fitted with a crank-case heater since otherwise it would not start when cold outside.

Any thoughts greatly appreciated

Cheers

[tradybrad]

hey jimbo what refrigerant is the system running? what were the refrigerant pressures whilst running?

[nike123]

Most likely it's dead and uneconomic to repair but I wondered what kind of failure this has experienced?

It could be as simple as refrigerant leak.
Check charge by recovering refrigerant and weigh recovered amount. It must be within 1-2% of nameplate weight. If it is not in that range, you have leak which must be found and repaired and then unit should be charged by nameplate weight.
If it is in that range than you maybe have inefficient compressor or 4-way valve which has excessive leak rate.

[Imp]

I had one doing the same recently in my own office. Just short on refrigerant. Working beautifully now. Whats the pipe run? Minimum run is 5 metres. This can cause problems. What is the model number?