Hobart F1 Error Code

What does Hobart F1 mean?

F1 is a fuse located on the relay board of the Hobart AM16 dishwasher. When F1 opens, the 24VDC control signal to the built-in chemical pumps is interrupted, stopping detergent, rinse aid, and sanitizer injection entirely. The machine continues to wash and rinse mechanically, but chemical dosing halts, which compromises sanitation and wash quality until the fault is resolved.

Symptoms

• Chemical pumps do not energize at any point in the wash or rinse cycle.
• Detergent, rinse aid, or sanitizer are not dispensed despite full chemical bottles.
• Machine runs full wash cycles but ware comes out unclean or unsanitized.
• No audible click or motor sound from the chemical pump assembly during cycle.
• Chemical-low error codes (074, 075, 076, 077, 079) may appear due to absent dosing signals.

Common causes

• Fuse F1 on the relay board has opened, most commonly from an overcurrent event.
• Loose or corroded wire connections at one or more chemical pump terminals.
• Chemical pump motor malfunction drawing excessive current and blowing F1.
• Extension card (A6) malfunction disrupting the pump control circuit.
• Power supply PS1 has lost its 24VDC output, depriving the pump circuit of operating voltage.
• Incorrect machine type or chemical pump parameter selected in the service menu, causing wiring mismatch.

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Diagnostic steps

1. Disconnect power and locate fuse F1

   Press the power button for 5 seconds to drain and shut down the machine, then disconnect and lock out all electrical circuits. Open the control compartment and identify the relay board — F1 is the fuse protecting the chemical pump output circuit.

2. Test fuse F1 for continuity

   Remove F1 and check it with a continuity meter. An open fuse reads no continuity. Note the exact amperage rating and replace with an identical-rated fuse as specified on the AM16 wiring diagram.

3. Inspect chemical pump wiring connections

   With power off, check all wire connections at each chemical pump (detergent, rinse aid, sanitizer). Reseat any loose connectors and look for corrosion at the terminals — chemical splash can cause corrosion-induced resistance that blows fuses.

4. Check 24VDC output from power supply PS1

   After replacing F1 and restoring power, measure the DC output voltage at PS1. A reading below 22VDC or absent output means PS1 is degraded or failed and must be replaced before pump operation will resume normally.

5. Verify machine type and chemical pump parameters

   Enter the service menu (page 66 of the AM16 Customer Support Manual) and confirm the machine type and chemical pump parameter settings match the installed configuration. An incorrect machine-type selection can cause erratic pump behavior that trips F1.

6. Test pump operation and monitor for repeat fuse failure

   Run a manual prime cycle through the Manager Menu (chemical menu → Prime Chemical Pumps) and listen for each pump to activate. If F1 blows again during priming, isolate each pump individually to identify which pump motor has failed.

When to call a professional

Contact Hobart Service if fuse F1 blows repeatedly after replacement, if PS1 power supply output is absent, or if the extension card A6 is suspected faulty. Chemical pump motor replacement and relay board-level diagnostics are best handled by an authorized technician who has access to the AM16 wiring diagrams and factory diagnostic tools.