Replaced water condensor

[cretan]

I recently removed a water coil and replaced it with a air-cooled condensor on a air conditioner.The compressor is inside the building.It is a capilary system so I charged it with the superheat method with a chart I found online.75f ambient,50psi suction,line temp 30f.After running for quite a while the lines freeze-up and the top of the compressor is very cold.The A-coil lines are frozen also.I can't see the finned side of the coil to see if it is frozen over.Head pressure is 250psi at the compressor.The pressure returning from the outdoor condensor going to the a-coil is 180psi.Is this pressure too low?Do I need to put a cycling switch for the condensor fan?Is my charging method flawed?

[Tesla]

Hi Cretan
Tricky one here, The head press should be rule of thumb - 18-21 K above the air on. A recent job I've seen where water was changed for air is 5 dead compressors on a unit with 3 comps. So I think floodback prevention is required. As for the charge you can go on superheat and current draw.
Good luck

[cretan]

thanks for the reply.I checked the furnace filter and it was dirty.I cleaned it and am running the unit now.Will find out soon if that was the problem.So is 180 too low pressure after the condensor?

[nike123]

So is 180 too low pressure after the condensor?


That depends on outdoor ambient temperature.
What is your outdoor temperature in moment of taking pressure reading?

The real problem is big pressure diferential from compressor discharge (250PSI-180PSI=70PSI) to point where you measured 180 PSI. If that is measured after liquid line filter-drier, You should change filter drier and then see what pressure difference it is. If that is measured before filter, than your piping is not properly done/selected or you have to long pipes.

[wambat]

I agree with nike123. the pressure drop doesn't make sense with that kind of drop the drier should be cold to the touch.

[cretan]

What is your outdoor temperature in moment of taking pressure reading?
Was 75f when I took the reading.reading was before the drier.drier is after the condensor.