I am working on a very old Jackson and Church 20 ton RTU. It has 3 unloaders sitting on the top of the compressor. We are currently experiencing near 100 degree ambients and this unit is tripping high head control. I have instructed the resident maintenance crew to clean the 2 condenser coils extensively which I am assuming they have done. These coils are close to 6" thick and require a lot of cleaning to make any difference.
Over the years this unit has been sliced and diced. It was originally a multizone, hot and cold deck. Now it is a straight cool or heat, minus the zones.
I realize the unloaders should be working on 1st or 2nd stage cooling calls. The original compressor I am pretty sure only had two unloaders, this one has three. Either way, I am thinking if I drop out one of the unloaders at times of high head I might be able to stop the manual trip control and if that is the best answer would I go about installing a auto reset psi controller with a adjustable time delay so it doesn't short cycle? any suggestions would be greatly appreciated. I will start with the cleaning and fan check out first, just getting armed before I make the journey. I know it is not overcharged. Thanks in advance!