Cascade unit will not reach -80°C, holds at -50 to -60°C

High-stage undercharge → cascade heat exchanger not cooled enough

Check: First see whether the low-stage compressor is cycling on the pressure control. If it is, compare the high-stage thermocouple readings against the service manual values.

What to do: Maker's procedure: adding 1 to 3 oz (about 30–85 g) of R404A to the high stage usually solves it. 🚨 If more than 3 oz does not help, stop adding — the high-stage capillary assembly is restricted and must be replaced.