Need help with odd refrigeration problem

[brankin]

I have a 110v AC refrigeration system (Copeland) R134a, with 4 cold plates. I had problems with the old unit when it suddenly started to overheat the compressor and shut down. The plates and charging system were normal and the box would get down to -15 which is in the range it was designed before it started failing. I replaced the unit with a direct replacement and today when I installed it, it started doing the same thing.
It has a sporland expansion valve and I have a warm intake line and cold on the backside of the expansion valve so I am assuming that it is working ok. Feeling the cold plates on the back side of the valve, 1 and 2 and 4 are chilling nicely while number 3 feels somewhat warmer.
The gauges read 25psi on the suction and 175 on the high side with the ambient temp around 90 degrees f. I have looked all over for an answer for what it should be and the results are all over the map.
Any idea what would cause the compressor to overheat? One last thing, when I was putting it in, it appeared to have spilled some oil (1-2 oz) so I call my friend who was an AC tech and he said it was nothing to worry about as the refrigerant has oil in it.
Right now, I am letting it cool off and tomorrow, I will put 2 oz of oil into the system and try it again. Also, do you hold the can right side up or up side down when you charge the system.

Any refrigeration types out there that can help me troubleshoot this system....Please

[Zil]

How clean is your electricity? Good volts and cycles? Low volts will overheat and finally kill compressors.

[brankin]

Voltage is steady at 110v and I am hooked to shore power. When the compressor heats up, I see a 30 amp spike and then it shuts down.

[ctl411]

What where is the condenser? Air cooled dirty not enough air flow? Water cooled plugged line, bad flow, air pocket in it?

[brankin]

This is an air cooled unit with a water heat exchanger plumbed into the high pressure side.

[ctl411]

How's the water flow? Do you have a fan on the air side? Also pulling down the plates from 90 deg temp is a big load. It may be OK once the box gets cold. Put a fan on the compressor until the box gets pulled down to temp or pull it down over night. Then see if it will maintain the next day without the extra fan on the compressor.

[GordMay]

Originally Posted by brankin

... Any refrigeration types out there that can help me troubleshoot this system....Please

Richard Kollmann ➥ Cruisers & Sailing Forums - View Profile: Richard Kollmann

➥ Kollmann Marine

[bglad]

I had an expansion valve go bad or clog on some equipment I run. It was a five ton unit and was working fine until the valve would clog or stop then the compressor would make a heck of a racket and trip its internal relief valve.

[RaymondR]

If your compressor suddenly draws 30 amps and then shuts down it could be because the compressor is getting a slug of liquid refrigerant which is very bad for it.