Any Ideas? Worrying noise from Fujitsu ASY 30E

[MrThin]

HI,

I am looking for some suggestions on why a 4 year old single phase Fujitsu ASY 30E 8kw R407C non inverter unit makes a worrying comp noise on start up.

As the condenser cycles / starts, it sounds like the compressor is starting properly but then followed by a deep vibrating noise and what sounds like the compressor going through a surge, this lasts for 2 seconds and then operation resumes normally, the hi pressure is fine, the low is 5psi down. Suctions line starts to freeze after some time, although minor and i am told this is not uncommon for these units. Could this be flooding / and the comp stalling, any other suggestions / tests. I am sure the charge is near correct as it was weighed in last year, it may be 30g over at the most.

Many thanks

[ernestlin]

Hi, MrThin(are u really a slim guy?:D), I regard the big noise may be due to liquid refrigerant migration, does the compressor have a crankheater?the evap. pressure is too low, the temperature of R407C in 5 psi is -31 F, it's not the range of air conditioning.. if your refrigerant charge is correct, there may be blockage in suction lines..

[MrThin]

Hi, thanks for the suggestion, i will check with Fujitsu technical but i dont think it can be the crank heater as it happens when the unit has been running for some time in high ambient. The low press is around 100 psi, i remember checking it against spec for conditions and it being 5 below spec. Think i will have to into more detail and recover, re charge and watch pressures whilst noise occurs. Just thought it might have been a known prioblem with unit.

[setrite]

The low press is around 100 psi, i remember checking it against spec for conditions and it being 5 below spec.
Low Pressure of 100 psi is too high. If it used for Airconditioning Low Pressure should be around 65-75psig.

[frank]

Low Pressure of 100 psi is too high. If it used for Airconditioning Low Pressure should be around 65-75psig.

a difficult statement to make when you don't know at what frequency the compressor is running and if the system has non-condensibles

[rbartlett]

a difficult statement to make when you don't know at what frequency the compressor is running and if the system has non-condensibles

A non inverter Frank non inverter...;-))

However if you check the chart the suction should -as mentioned- be nearer 65psig. You appear to have overcharged it

Cheers

Richard

[frank]

A non inverter Frank non inverter...;-))

Cheers

Richard

OOOOOPPPPS :o

[MrThin]

Sorry for the inaccurate info, trying to remember the readings and made a mistake. It must have been around the 60 psi mark, got confused thinking R410a,I will get the gauges on it and come back with accurate readings, temps etc. My intial querie was is their a common cause for this type of compressor surging? I am thinking of measuring current to comp during and after this condition to see what i can find.

[bebad]

is the comp recip. or scroll? older toshiba recip's made this awfull noise too, check amps & voltage for sure. Power supply adequate? is system in domestic/smaller commercial application where mains power isn't really up to running Aoy 30 fixed speed system, this unit does start about 65 amp

[bebad]

suction pressure on 407c 48-62psig, you will find frosting common too