My experience/knowledge. Tech school with ice machine field experience. Also some commercial refrigeration field and shop expierence. I was a food equipment (mostly restaurant, bakery, deli, meat dept) for several years.

I am trying to help a neighbor/friend with a problem with a York mod e2rc048s06g. It is an 8 yr old 4 ton r22 heat pump split system.

On a call for heat there is a 5 min short cycle delay and then the compressor will start but only run for a few seconds. There is no indication of a compressor start problem and was proven later.

The control board (part # 031-01954-000) has low voltage inputs, defrost t-stat input (55-31), hi pressure switch input (400-300) plus outputs for the cond fan mtr and reversing valve. Finally there is an 'M' terminal that powers the comp contactor coil.

After I did some reading about the control circuit I determined that I was loseing the 'M' output but not my R to Y input( tested with meter plus indoor fan continues to run). From what I understand about how the board works an open pressure switch or board fault is all that should stop the compressor after it has started. I replaced the board with a known working one (mine) and got the same symptoms. I then tested by putting a jumper on the board pressure switch terminals while having an ohm meter on the switch terminals. The compressor started and continued to run but I saw no indication on my meter that the switch opened even breifely.

After I had the unit running for awhile I put my gauges on it, but with no heat pump field experience, the results were meaningless other than at no time did the pressure approch anywhere near 400 psi. Also I had a decent split in the house which would indicate there were no charge or reversing valve issues.

At this point I normally would have condemned the pressure switch and replaced it but this particular switch (part # 025-33305-048) is brazed on which would require either recovering the charge or at least isolating it into the evaporator. I'm reluctant to do either without being positive that the switch is defective.

Can anybody confirm that I'm on the right track and know a better way of testing the pressure switch other than with a digital ohm meter. Or am I missing something about how that board works.

The unit is now operating but with safety removed so a quick solution is needed.

Also, what are your opinions about a braze on pierceing valve with a charged system and an aftermarket screw on pressure switch.

Thanks for any and all input.