You might also check from common on your board to both the low & high pressure switches. I had a late model Carrier last week do the exact same thing yours is doing. It would run fine for a day or so, then start short cycling ... like off/on every 10 seconds. I made sure i had 24vac in on my R & C terminals and that i had 24vac on my Y1 & C terminals. I let the unit short cycle off... making sure i didnt loose my 24vacs on the terminals... then did the same thing with the low & high pressure switches, making sure they were closed during the short cycling. I ended up replacing the board and everything has been working fine since.

Hope that helps

I'm getting 24 volts on the R&C terminals. I don't see a Y1 terminal, though.

I assume that the Y1 terminal is the Y terminal on my board.

I am getting 24 volts into the board between Y & C. The board also briefly sends 24 volts to my contactor and my fan/compressor kick on briefly. I lose 24 volts (fan/compressor shut down) for about a minute or so and then get 24 volts back and everything works just fine.

The big mystery is why is my board sending 24 volts to the contactor for a half second before stopping? Weird stuff.