FieldBench
Carrier codes

Carrier

24

Protect

Secondary fuse open

24 V fuse on the IFC.

Walk 24 in Diagnose

13 plates — walk the one on the cabinet

First check

1 Find the 24 V short before you replace the fuse

On Carrier 58CVA 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 / ABCD miswire, HUM/EAC, valve harness. Replace fuse 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 fuse only after the short is gone.
  • Short on HUM/EAC, valve harness, or someone landed 24V/W on ABCD.
  • Replace fuse only after the short is gone. Repeat 24 after an ABCD miswire = look at D and the outdoor pair.
  • HUM/EAC, valve harness, or 24V landed on ABCD.
  • Replace fuse only after the short is gone.
  • Tstat / ABCD miswire, HUM/EAC, valve harness. Replace fuse after the short is gone.
  • Tstat short, HUM/EAC, valve harness.

Plates that use 24

Same number, other makers

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