ycas help

[turbovac]

ycas 170, hp jumped, motor sensors jumped with correct resistors, motor/
amperage m1-m2 jumped, when starting display shows correct amps,
still trips on low current/mp/hp. can any one help?

[megohm]

How was the compressor performing before the failure that you are working on now. If the compressor is not pumping or there is a loss of refrigerant then you can get this failure. Did you jump out low pressure sensor and a dumb question is the discharge valve open. What seris is this machine a f or g.

[cperk]

Is the switch in the breaker for this circuit made? I think it's in series with M1 or M2 on M.P. if I remember correctly.

[klove]

Do you have a set of auxiliary contacts stacked onto the top of the main contactor? If not, chattering could be an issue. You could simply have a bad connection in a plug or on a terminal. That particular fault indicates one thing: there is a call for the compressor from the microprocessor but there is no (or not enough) current feedback telling the micro that the compressor is running, so it thinks that it has a problem. The causes for this are many and varied. Fellow asked me once if the windings all opening in the compressor without grounding would cause this fault. Told him that it would. No idea where he came up with that, but hey, it's just implausible, not impossible...

[yorkman_gr]

the most common trouble on this MP is loose contacts, moister, and oxidation also make sure that the two HP switches are well tight up and reset the blue batons, the MP signal is passing in series with the HP switches

[cheelr]

I had one do this once, a rental. Drove me nuts until I checked the tightness of the white neutral L2 wire terminations coming off the compressor contactor/s. The loose common wire was intermittently opening the current path to keep the compressor coil energized but in the common/neutral section of the circuit, all the usual suspects could be jumped/eliminated but it would still trip. Give it a look.

[ktxkrew]

I had this problem before and found one of the aux. contacts on the compressor contactor burnt open. It had 2 sets so i just moved over to the other side and it ran. Follow your schematic from that breaker and see if all the auxillarys are acting correctly by manually pushing the contactors in.

[cperk]

If you disconnect everything is M1 and M2 closed? I have seen a few of those Texas Instrument motor protectors go bad.

[turbovac]

cperk, you nailed it, the switch in the breaker would trip just before
transition & remake as soon as the compressor shutdown. thank you for the
help & thanks to all who responded, I really appreciate it.

[cperk]

Even a broke clock is right twice a day.

[cheelr]

" the switch in the breaker would trip just before
transition & remake as soon as the compressor shutdown. "

So was the remedy a whole new breaker? I knew those breakers had switches in them, but I didn't know the little trip indicating contacts could ever be closed then open then closed again while the actual breaker remained closed. That's a weird one, but I'll now have another thing to lookout for.