Tools/ Calculators/ Target Superheat Lookup
Fixed-orifice charging

Target Superheat Lookup

For fixed-orifice (piston / cap-tube) systems. Type the indoor wet-bulb and outdoor dry-bulb. Get the target superheat charge-to value. For TXV systems, use subcooling instead.

Inputs

Take this with a sling psychrometer or anemometer at the return-air grille.
Ambient temp in the shade at the condenser.
Target Superheat
Enter wet-bulb and outdoor temp above to see your target.

How to use this on the truck

  1. Run system for 15+ minutes to reach steady-state.
  2. Take wet-bulb at the return grille; outdoor dry-bulb at the condenser.
  3. Measure actual superheat at the suction service port (saturation temp at suction pressure → suction line temp).
  4. Charge until actual superheat matches the target ± 3°F.

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