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Hi Randy,
You say the compressor isn't cycling, but don't indicate whether it is even running.
If your compressor is not running at all then start by checking the low side pressostat on the accumulator with an ohmmeter. If there's no continuity there then the compresser simply won't run. That can be either a sign of loss of refrigerant (common) or a failed pressostat (less common). I have had one of those fail in recent years where I initially assumed it was the usual loss of refrigerant. When they fail, I believe they always tend to fail open, so no compressor even if there is adequate refrigerant. When the refrigerent level is marginal or the pressostat is just starting to fail then I imagine you would see more rapid cycling, but I'm not familiar with that. Usually by the time I see a problem there it's game over, the system has either leaked down or the switch is toast or both.
Next would be to check the high side pressostat on the condensor rail under the rad area. It's the violet one with one green/black and three green/red wires. It's a normally closed pressostat. If there's no continuity there then again the compressor won't run. When that pressostat fails, I believe it normally tends to fail closed so the compressor would tend to continually run and you won't get normal cycling. That's a bit difficult to test without the right equipment. I believe too much refrigerant can cause more frequent cycling there, while too little refrigerant will mean less cycling there. Again, in theory, if the pressostat is just starting to fail then you may see some less frequent cycling on/off there, but I'm not familiar with that.
Now if your compressor is running, just not cycling normally, then beyond the above basic pressostat checks there's a lot more on compressor cycling issues in the FAQ https://www.brickboard.com/FAQ/700-900/HeatingAirConditioning.htm#ACCompressorClutchCycling
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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