Increased orifice size - suction line pressure went DOWN!
It's a Lennox HS29A-043 4-ton R-22 unit.
Got it second hand to replace a bad unit. Cools okay but subcooling is 12 deg too high, Suction line pressure 20 lbs. too low. 'Mkay.
Recovered a pound and a half of R-22 to be on the safe side. Pumped it down. Pulled orifice, found .081. replaced with .086 per the book.
Leak check - pulled vacuum. Suction line now 20 lbs. LOWER than before! Like 30 psi. A larger orifice should give a higher suction pressure, not a lower one. Put the recovered R-22 back in. Pressure now back up to where it was before. Subcooling close to normal now.
What gives? This unit seems to behave backwards from what it's supposed to.
Still cools okay but when the temp gets up to 106 every day here, I'm gonna have a frozen up evaporator with this pressure.
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Installing used equipment was your first mis-step.
And I think that is a 3.5 ton unit, not 4 tons.
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No offence man, but you need to hit the books before touching another system.
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1. It's a 4 ton unit.
Originally Posted by 2old2rock
2. FYI they don't make R-22 units new any more.
Typical low airflow issue also 12 degrees subcool does not mean much in a piston metering device .is the coil clean and what happened to the other unit
Dave net didn't show that model number for current or out of production units. Closest is a HS29-042 which is a 3.5 ton unit. Measure your air flow first then check superheat.
Did you change the filter drier?
What is the suction pressure now? 20-30psi could mean a whole range of different issues. Airflow, system charge, restriction.
Have a picture of that model number. I say HS29A-043 doesn't exist.