Hunter Pro-C Pump Error: Diagnosing PSR & 220V Pump Issues

Hunter Pro-C "P ERR" (pump error) with a 220V pump and Hunter-22 PSR indicates the pump start relay isn't closing both legs of the 220V circuit—running the pump on 110V, which trips the breaker.

Root Cause

The Hunter-22 PSR has two sets of contacts (for L1 and L2 of 220V). If one set is pitted, burned, or blocked by an insect, only one leg closes. The pump draws excessive current on single-phase → thermal overload/breaker trip.

Diagnosis Steps

1. Inspect PSR contacts. Open relay box (KILL POWER AT BREAKER FIRST). Look for:
   • Burned/pitted contacts
   • Ants/debris between contacts
   • Loose wire terminals
2. Test with multimeter (power OFF): Check continuity across each contact set when coil is energized (24VAC from controller). Both should close.
3. Evict insects. Ants love relay warmth. Clean thoroughly; seal conduit entries.

Fix Options

• Replace PSR contacts (if available) or entire PSR (~$60–$100).
• Upgrade to a 2-pole definite-purpose contactor (e.g., Square D, Mars) — more robust, ~$40.
• Add insect barrier: Seal all knockouts; use insecticide granules around box (not inside).

Why It Worked Temporarily

Cleaning the pump disturbed debris/contacts just enough to make brief contact. Vibration/heat then reopened the faulty leg.