FieldBench
ICP codes

ICP

24

Protect

Secondary fuse open

24 V fuse on the IFC.

Walk 24 in Diagnose

3 plates — walk the one on the cabinet

First check

1 Find the 24 V short before you replace the fuse

On ICP N80ESN an open IFC fuse is a short on W, Y, G, HUM, EAC, or a data pair landed on 24 V. Unplug the thermostat / data harness first. Tstat short, HUM/EAC, valve harness. Replace the fuse only after the short is gone.

Expect: Fuse out. 24 V transformer still good. Harness isolated.

The rest of the walkthrough is Diagnose.

On the plates

  • Tstat short, HUM/EAC, valve harness. Replace the fuse only after the short is gone.

Plates that use 24

Same number, other makers

24 on ICP is not the same code on these plates.