Fujitsu compressor suspect!!

[phase3]

First off.......... New to the forum, so hello to you all

Working on a Fujitsu ceiling cassette (R410a) today. Initially brought up a fault code of which was traced to an lp issue. Low and behold the system hadn't a drop of gas left. Pressure test revealed a small crack to the flared service valve tapped off beneath the 3 way valve. Brazed this. Pressure tested (all fine), then vac'd out, recharge accordingly.

The base charge was 2400kg (anyone know the maximum pipe run before additional charge??) Suction registered less than 60 psi?!?!?! whilst the liquid completely frosted over on the service port and looked set to freeze further back up the pipe run on the high side....had pulled back lagging to reveal this.

Thing is.Compressor running, but condenser doing little duty as no heat exchange apparant with the fan blowing in my face it was ambient cool-no warmth whatsoever.
Suspect internal compressor damage, wondered if it could be a pumping issue??? I checked to see that both valves were back seated and they were. Realise I could do a pump down test on this but wondered if anyones encountered something similar that could save me the time and just write this pot off altogether???

It was like the compressor had only enough clout to pump to the beggining of the liquid line and go no further. No suction??

Hope it's not a blockage.

Any thoughts appreciated.

Cheers,

Jon.

[rbartlett]

frosting on the pre expansion line and low suction usually means low on refrigerant.

cheers

richard

[phase3]

Thanks for reply.

I appreciate that that would be the usual reaction from low gas, however the reason why I was overly cautious about the compressor was because the pot had been running previously with very little gas and was found the first time round red hot and near enough cooked!

Forgot to add that. Sorry.

I will double check the pipe run later, as I could have been decieved by this.

Cheers.

Jon.

[rbartlett]

Thanks for reply.

I appreciate that that would be the usual reaction from low gas, however the reason why I was overly cautious about the compressor was because the pot had been running previously with very little gas and was found the first time round red hot and near enough cooked!

Forgot to add that. Sorry.

I will double check the pipe run later, as I could have been decieved by this.

Cheers.

Jon.

frosting is either as I say or a restriction in the drier/filter capilary section.



Cheers

Richard

[Andy W]

I had a Fujitsu cassette last year with 2 filter driers behind the compressor and both were blocked, a real swine to get to.

[bebad]

Phase 3; cooked the oil from running with no gas, always blocks dryer, no Low Pressure switches on these systems, once comp goes out on over temp this system won't restart UNLESS, and this has happened to me before, the customer resets mains to system and restarts operation, they then think they've FIXED it!
Continually resetting mains when over temp of comp occurs, should the case be so, forget it. Whole new system required, you will be there forever trying to retrieve cooked oil from dozens of blocked filter dryer changes.
Ps. there's only one dryer in this system and all other Fujitsu splits as far as I'm aware.

finally, does suction gauge conected to suction service port on Cond. hold a vacuum or take a long time (hours) to equalize?
Also is this a 3phase system, 3phase????

[John Wood]

Phase 3. Why would a low suction pressure and frosting on the low pressure liquid line make you think the compressor might be on it's last legs???