copeland heat sieze

[icecoolgauteng]

sorry we missing but we back
hollo to all!!! but now

repairing at walkin freezer thats work for years
but now always overheating
as we set it up on firday running gas 408
oil temp 60degrees
suc -20
hp 1900
all working well cheak it saterday freezer at -5 degrees
sunday the same
but monday morning it siezed
and this is the sameproblem over an over

[monkey spanners]

Hi Icecool,

I've only ever seen one Copeland (3HP) piston compressor sieze its pistons in the bores (which is what heat sieze makes me think of) and this was due to very poor oil return on a newly replaced compressor on a system which then had lost some refrigerant causing the poor oil return.

We got it working again by reoming the head and putting some oil in the bores and pushing them up and down by hand till it free'd up, reassemble, fix leak, re charge and worked fine.

What size compressor are you working on?
What type of oil is it running, mineral?
Have you stripped it to see where it has siezed?

What units are you using, C or F, psi or bar and whats hp1900 a measurment of?
How long has the 'always overheating' been going on? since you changed the refrigerant to R408A?

Jon

[That's too cold]

So it operates for about two days then it seizes up.

1. Is it pumping down from thermostat and not shutting off?
2. What other oil related problems could there be?

[chilldis]

how many hours are on this compressor? I have seen copper plating on the rod bearings on high hour compressors. they heat up, the copper expands and the compressor siezes up.

[alan wolf]

hello

sorry dont have a comparator for 408 but take it its 19bar hp and -20deg c evaporating, need definite readings and suction temps as well as any liquid site glass indications and compressor amps in relation to fla. another problem with freezers is people leaving doors open too long and coil frost up. Defrosts need to be considered, did coil ice ove stopping air flow? maybe floodback caused problem.
AWW