I'm working on my uncles heil 3 ton condensing unit.
I do mostly residential gas and oil but am learning ac this year.
My uncle has been complaining of a hard start so I went over to check it out.
The unit is a r-22 condensor here is the plate
This is the build sheet from the goodman a/h it's attached to
I attached my testo 570 manifold to monitor the pressures on start up.
Before starting the unit sits at about 130 psi equal with maybe a few pounds difference.
On start up the high side climbs to 350+ and hits the high pressure switch and kicks the compressor.
The compressor restarts and climbs, but starts dropping before it hits the switch. The second run cycle the compressor reaches running pressure and sounds smooth. Today with a temperature of 80 outside I had 105* saturation temp on my liquid line which I understand to be good for r-22.
My evaporator temp seemed really low at 27-28* which made me think the unit was under charged or had leaked, but after more investigation I found he only had one central return with a 14x14 opening directly into the plenum that sounded like a vacuum cleaner.
We added two more 8" return flexed out about 15' and that helped pull much more air across the evap and raised the evap temp up to around 37-38*. I noticed through as I ran some liquid into my gauges that it had a reddish color for a second that I have never seen before.
So, now my low pressure sits around 65-70* with a saturation temp of 38*, my high side around 220 with a saturation of around 105-107*.
Once the unit is running it is fine but the really hard start and hitting the high pressure switch has me stumped.
I notice on the condensor it says txv Indoor and the unit has a piston orifice. I tried putting a hard start kit on the unit and a new turbo 200 cap just as a easy yes or no and it made no difference.
The filter drier on unit is a copper tube about 3/4 diameter brazed into liquid line. I've never seen one like this and am wondering if maybe it is restricted?
Any help or advice would be appreciated. I've asked some of the senior techs at my shop but won't be back in till tommorrow and not knowing is driving me crazy!!!