Help with a split

[Robearbam]

3 ton, hermetic recip. These are the things I'm observing. All summer, suction on the rise and head comming down. Last reading on a hot day 95PSI suction, 200 head. Superheat 15 to 16°. I'm not used to seeing these pressures with 22. Discharge temperature in the plenum about ten feet form the evap has always been 59 to 60°. Now it's 64 to 65°. I happen to hear the compressor kick off and the condenser fan was running...took everything apart and checked all electrical connections, cap good and the compressor was hot. No external thermals on this thing. It's a copeland compressor. Are they inside this can? Anyway, unit is running, probably not for long since I can't figure out what's going on. Valves??? I'm ready to replace the compressor...it's 5 years old. Pressures looked good at the beginning of the summer? Thanks for your thoughts and hope I gave enough information.

[jan behnke]

Replace the comp sounds like its not pumping right:

[piston broke]

I agree.

P.

[abid]

there is no more pumping sure.......

[botrous]

Compression rate approximatly 2.1 , that's a low compression rate , i can assume it's the compressor failing or or or , did you check the voltage that's arriving to the compressor ???? if the voltage decreases , the electric motor who turns the compressor torc will decrease ==> not enough force to pump with a good efficiency , as a matter of fact the compression ratio may decrease a lot . . .
Can you here noises coming out from the compressors like (pss or eshh) or soemthing similar?

[tonto]

Might be a dumb question but can you do a efficiency test on the compressor, does it have rotalock valves on the suction and discharge....

[US Iceman]

It sounds like everyone is on the right track.

If the condenser fan was still running, and the compressor was hot and OFF, it sounds like the internal motor protector was tripped.

If the compressor has the rotalock suction valve, you can close this valve when the compressor is running. The sucton pressure should rapidly decrease.

If not, shut the compressor off (with the suction valve closed). Does the suction pressure quickly rise?

What you describe sounds like a broken discharge valve in the compressor. The amps should be lower than normal also (less pumping).

I would change the compressor if the above proves true.

A separate note: Is the condenser clean, or has this been subjected to floodback. Something caused the valve to break??

Good Luck

[Robearbam]

The voltage is correct. I will try the access valve and see if the suction drops. The condenser is clean. The compressor sounds normal, I'm going to replace it as suggested. There are no pressure sensors on this. I would like to add a filter drier at the very least. Thank you all for the replies!

[Tony]

Superheat sounds far to high - should only be 5 - 7°C

[Robearbam]

Sorry Tony, I was using °F, I didn't specify that. It's just that here in the states we still use these measurements. Actually though, all my tools for our other equipment is strickly metric except for a few machines that are still SAE. It's a real pain dealing with both.

[botrous]

Welcome man , as the voltage is correct . . . as US Iceman suggested , did you measure the amps ? seems you are on the right way . . . .
PS : metric or american unit is really a pain in the A**

[Robearbam]

I haven't been back at the site yet but, I will be sure to check the amps this weekend. Unit is running and satisfying right now so, hope it holds up till I get back. It's been an exceptional hot summer here. Thanks for the feedback!

[wesmax]

Compression rate approximatly 2.1 , that's a low compression rate , i can assume it's the compressor failing or or or , did you check the voltage that's arriving to the compressor ???? if the voltage decreases , the electric motor who turns the compressor torc will decrease ==> not enough force to pump with a good efficiency , as a matter of fact the compression ratio may decrease a lot . . .
Can you here noises coming out from the compressors like (pss or eshh) or soemthing similar?

are you implying that the voltage drop would change the speed of the compressor , i am thinking this is not rite, the only thing low volts will do is affect the amps and the starting ability of the commpressor. the temp of the windings will also increase. but I do not see how the compreeion ratio will have anything to do with volts.

wesmax

[afeef]

hi all
5 year compressor is not old, compressor should serve at least 10 years
but i cant give any excuse of the high pressure suction and low pressure discharge rather than a faulty compressor,
the most common reason for compressor damage is lubrication system , may be it is the reason for damage in this short period
when you replace compressor , check the oil condition of the faulty one , its colour,smell,viscousity and voluem
i beleive that oil is the reason of damage
best wishes

[wesmax]

this is mabe one reason for failure but there are several other reasons valve failure is a popurlar one just next to electrical failure, when you remove the compressor it is best to check the system not just the compressor most of the failures are system related except mabe for some electrical problems which can be power related.

wesmax

[Robearbam]

I replaced the compressor at the end of our summer and all is well. I didn't find anything wrong with the system as far as any restriction. A friend of mine told me that sometimes a internal relief valve can go bad. I didn't realize hermetics had these. I took one apart some years ago and found a broken reed. Never noticed a relief of any type. Added a sight glass and filter...by the way, no band heater on this compressor, the replacement does???

[wesmax]

well it is common to have a valve go in a compressor but a heater is a good idea. is the compressor in a cold area, mabe should have a suction accumulator.

wesmax