I have come across a lennox 4 ton condenser hpxa16-048-230-01. This is 410a heat pump system. I would like to replace the compressor to 3 ton r-22. Is this feasible? Would I need to change reversing valve?

It could be done but you better know exactly what you are doing. The real question is why go to all the trouble?

It could be done but you better know exactly what you are doing. The real question is why go to all the trouble?Indeed, what is your objective here? This project, as described, has great potential... for failure.

You would have to flush system with R11 and the reversing valve has to be changed and the expansion valve has to be changed or orfice to be changed and yes it will work ,you will have to play with fan speeds to get a 18-20 degree drop but you will never get the efficiency of 410A. Mikie D.

Call my friend Lou he can answer any of those type of questions 215-989-0168