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We have a 2 ton split system that we recently installed that runs fine for awhile then the high side begins to drop, run up, run up drop until finally the safety switch goes off on high pressure.

We replaced the filter/dryer thinking that there might have been a restriction or that the gentleman who brazed it applied to much heat since he has a bad habit of not using a wet rag during installation and has had filter/dryer problems in the past.

I am leaning towards a restriction in the high side, but am a bit thrown as sometimes the unit goes right into an extreme pressure on start up, sometimes it will run for 45 minutes before it does. It is providing normal cooling and we are not having anything freeze up on the lines or frost.

Right now we are considering replacing the 3/8 line, a-coil and filter dryer, but I hate being a parts changing monkey and would rather use this to learn and troubleshoot.

Hi,

High side pressure would be low IF you had a restriction. More likely to be overcharged.


Recover the refrigerant and then go by unit data and weigh in the correct charge.


Let it run 15 minutes to stabilize system and then check subcooling and superheat.


Also check unit amps.


Thanks,
Robert

Pretty sure you nailed it. Think through what you said and discussing it with the Super, it came to our realization that when made the switch from r-22 to r410a they started supplying the filter driers and we believe the factory charge includes the pre-charge for this. But we added the previous manufactures recommendation for the filter dryer. When we pulled that, so far so good. Just going through some new literature and still testing, but pretty sure we are on the right track.

TY Much! (^^^)

Hi,

You're very welcome, happy to help.




Take care and best wishes,
Robert