The 410-a txv runs at much higher pressure so r-22 works but an r-22 txv can't handle the higher pressure.
Hows this this one ,by accident an R22 3ton condenser was replaced and I didn,t realize the old cond. was R410A mainly because it was 12 years old and rusty and just didn,t think it was 410, anyway replaced it charged it and it ran good pressures 10 degree superheat and 19 degree drop across the evap coil and cooled perfectly, that was 4 months ago and no problems ,go figure,but I did see a R22 txv on 410a system and it didn,t work at all, the 410a txv did adjust to the temp. of R22 and metered accordingly Mike D. Believe it or not
