R12 to R12a converstion

[chromguy]

I just added A/C to my 87 Sundance with parts from my 88 Shelby Z.
I used 2 cans of RedTek as it was equivalent to 36 oz R12 as the system was empty and under hard vacuum (10-2 torr)

Car at 900rpm at 26C (79F) outside with fan at max and recycle on as well
vent temp was at 8.4C (47F)

High Side 150psi
Low Side 22psi

12a manufacturers recommend 30-38psi on the low side and comment the low side is about the same(as R12) and high Side is 5-19% lower (than R12). My gut feeling is my charge is low and a could use a bit more.
The FSM only describes R12
Discharge temp 39-50F
High Side 180-235psi
Low Side 16-30 psi

Your comments are welcome.

[black86glhs]

The pressures do sound a little low, but the air temp is good. If you add more, you don't want to add a lot.

[turbovanman²]

Try addding a bit more, they are a bit low. Mine cycles around 25-40 psi on the low side.

[chromguy]

Thanks you for the advice. I measured again after the drive home from work and the values are higher
170 high side
32-25 low side

I did notice I can feel the engine slight jerk with the AC clutch engages and disengages. More than I expected but this is my first AC with manual transmission.

[black86glhs]

On older cars like these, they will especially in lower gears.