I wanted to get some input on something I’ve noticed during service and checks on the ‘DS Copeland scroll compressor units. Part of our service routine is to document operation of the high and low cutouts.
I first noticed on an earlier occasion of pulling the liq. sol coil allowed the comp to pump down approaching zero (gauge).
Copeland does not like these to run anywhere near that low (below about 20 or so psi if I recall.
So calling tech support was advised the system would (should) protect from loss of charge for example, that perhaps it was delay’ between my gauge reading and the system’s response, and it would be safe to run a test briefly enough to try it again.
Did a test on a second different unit, it did the same thing even letting it linger a bit longer before pull the plug’.
These have a Low Pressure-to-analog transmitter by the way.
I am skeptical about the gauge lag’ is this case. On a normal stop from cooling /pump down I can always reliably see them pulling down typically to around 4-10#. Liebert’s control target cutout point is actually quite a bit higher than that and if I’m not mistaken part of that difference may be at least partly system response lag.