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22-02-2018, 10:30 PM #1
Compressor No Start intermittently on Self-Contained application.
Hi guys,
We have been building this model display case for years. Copeland has retired the condensing unit we had been using and recently replaced it with a new model. Other than the new condensing unit, nothing has changed. I say this with regard to all aspects of the case including evaporator, piping and controls. We have built a few cases with this new unit without issue.
It is a 1/2 hp. 404A Copeland reciprocating condensing unit. 115Volt / 60hz. Cap start/ induction run. It is brand new out of the box from Copeland.
The problem;
At the initial start-up there are no issues. Cycling through the initial pull-down the t-stat preset temperature is satisfied and the unit cycles off. Everything about this initial cycle is as expected. The operating pressures are as we expect and even the sound of a running cycle is fine. When the t-stat calls for the second cycle and subsequent starts thereafter, the external over-load trips a few times before compressor starts. Unplug the unit for half an hour or so and the above scenario repeats.
What is known;
Ambient Temperature 68°f
Supply Volts, 116V
Running Volts, 116V
LRA 39.5A specs are 40.0A
RLA 9.8A specs are 10.0A
Discharge PSIG 210 running
Suction PSIG 55 running
Windings; run .8 start 3.8
My first thoughts are to just replace the start components, so that's exactly what I did. Cap, Relay and O/L. Same issues.
It is a TXV system and although the charge is standard for us and head wasn't high, I reduced the charge. Same result.
Thanks for letting me pick your brains.
Ken