Automotive Air Conditioning Information Forum

Pressures s/b no different than what you are used to in a vintage system. At 1500 RPM low s/b approx 35, hi approx220-250 depending on ambient
I have no knowledge of the VIR system,(others here do) but for best performance you cannot beat a TXV. It self adjusts to the load applied. An OT is a fixed orifice, ie an average of what might be desired.

Well, the 1970 Cadillac had both a TXV, and a POA valve.

The 1975 VIR system incorporated both of those systems in to a single unit.

You should probably start with a TXV, and a Receiver Drier for this conversion. You can leave the additional accumulator in place, it does no harm.

Reduced compressor volume will mean a longer cool down, but it will eventually cool down.

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hi
The conversion that I have done
that use a POA ,,, TX Ext Equalised ,,vehicle uses a small corvette evaporator ,,This core is used by GM in alot of vehicles
big black a6 compressor ,,, small clutch hub eng fan

convert to
Block txv internal equal. original/aftermarket replacement evap core ,, electronic thermistor ,,, sanden 7H15 double v belt vert o ring connections ,, dual 14 inch elec fans [on with acon ]

The txv block is 8 inches further away from exhaust [located top /suction connection] VS the factory txv which was very close [bottom of evap liquid inlet ]

Insulated the evaporator box completely with fibre glass /foil insulation to reflect engine heat

1200rpm 90f day
175--190 high
28-40 low
44f vent in the shade
A little slow to pull down to temp ,,evap core would be considered small for vehicle size but I cannot fit a larger unit
System is FULL 100% R134a