CA-2-A16 Heater replacement/ongoing bleed & troubleshooting

Wow; that's unusual to see the round rubber cord. As Chris said, the Form A machines often have individual cloth-covered wires as opposed to the cord. But nobody has seen them all. 

Accessing the compressor wiring is somewhat "scary" but not difficult. You'll need to lay the unit on its side, with a cushion under the condenser to support it. Should be able to remove all but two of the screws holding the evaporator plate to the bottom of the unit.  Loosen the remaining two screws, so that the plate can be "hinged" gently away from the body of the unit. Move it away just enough to carefully un-staple and remove the cardboard surround piece from one side. With that removed, you can pull out the insulation stuffing and access the wiring. It takes a little dexterity to work in that space with a soldering iron; but it is very possible.  The key is to not stress the lines too much.

As for the NCG purge, you can not complete a NCG purge without the unit running. You can, however, begin the process. Some of these have built up such a high level of NCG that they are stalled or otherwise damaged and can't run.  You can do a static bleed, to release the "overpressure" of built-up noncondensable gas. The entire machine needs to be cool, below 80°F. Place a piece of clear tube over the service port and fill it with oil. Loosen the port, and observe the oil. If bubbles appear, allow them to escape. If the oil starts to draw into the machine, close the port. 

If there was pressure when you opened the port, with the machine stopped - then you had a severe NCG issue. Be sure to release all the pressure until there are no more bubbles; with the machine cool and stopped. Then close the port. If the oil drew back into the machine, you still will need to do the factory bleed procedure, but it may not be as severe of a buildup.

The factory bleed procedure works because the condenser is hotter than the boiling point of the refrigerant; and also because the gas is circulating in the system. The float chamber will collect additional NCG out of the system due to the running system. The factory bleed procedure includes running for a short time and bleeding for a short time. This allows the NCG to build up in the float chamber between bleedings. Doing it this way will reduce loss of refrigerant. 

Pre-bleeding with a cool machine will minimize the amount of methyl formate loss which happens during bleeding with the machine hot and in operation. Also we have seen these seize up during the factory bleeding process. This was likely because it had so much pressure to start with, the compressor couldn't stand the overloading for that long. The pre-bleeding will relieve extreme pressure which is immediately damaging to the machine; while the factory procedure (hot and running) will get out a lot more of the NCG by allowing the refrigerant pressure to push it out.