The most likely fix on an AquaCal that's short cycling or heating weakly:clean the evaporator coil and check water flow first — those are the two homeowner-checkable causes. Beyond that, you're into refrigerant or electrical territory, which is licensed-tech work. In our experience, Florida heat pumps fail in three ways: salt-corroded coils, refrigerant leaks at brazed joints, and contactor/capacitor electrical failures. Defrost behavior in cool weather is normal — don't mistake it for a fault.
AquaCal symptom quick reference
| Code / symptom | What it means | Likely cause | DIY or pro? |
|---|---|---|---|
| Compressor short cycles without warming the pool | Protection circuits tripping early | Low water flow (roughly 30 GPM needed) or a dirty evaporator coil | DIY first, then pro |
| Pool climbs only 1–2°F over an 8-hour heat call | Weak heat output | Clogged coil, blocked airflow clearance, or refrigerant lost through a leak | DIY first, then pro |
| Ice on the evaporator coil that doesn't clear | Stuck past a normal defrost | Normal defrost runs 5–15 minutes on a cool morning; persistent ice needs diagnosis | Pro |
| HP or LP fault displayed | High- or low-pressure protection trip | Water-flow or airflow restriction; beyond that, refrigerant territory | DIY first, then pro |
| Fan runs but the compressor doesn't kick on | Compressor not engaging | Contactor not pulling in, bulged run capacitor, or corroded compressor terminals | Pro |
Most common symptoms
- Compressor cycles on/off rapidly without warming the pool.
- Pool barely climbs 1–2°F over an 8-hour heat call.
- Ice on the evaporator coil that doesn't clear.
- Unit displays HP (high pressure) or LP (low pressure) faults.
- Fan runs but compressor doesn't kick on.
- Loud bang or whoosh followed by cool air discharge.
Diagnostic walkthrough
- Pin the symptom. Short cycling? No heat? Ice? Fault display? They diagnose differently.
- Water flow. Heat pump needs roughly 30 GPM (model-dependent). Low-flow protection trips early. Filter cleanings, valve positions, plumbing checks.
- Air flow. Top fan spinning at speed. Coil clean. Two feet of clearance on all sides. Florida pads with palm-frond debris choke heat pumps in 30 days.
- Defrost vs. fault. A short defrost cycle (5–15 minutes) on a 50°F morning is normal. See our heat pump defrost guide for full context.
- Visual leak inspection. Oily film at copper joints, missing brazing, tarnished compressor leads. Refrigerant doesn't evaporate — if it's gone, it leaked.
- Electrical. Contactor pulling in cleanly when the controller calls? Run capacitor not bulged? Compressor terminals not corroded green? Florida coastal pads shorten the life of these parts noticeably.
Step-by-step fix
Coil cleaning is homeowner-safe with the power killed and locked out: garden hose from inside the cabinet outward, soft brush on heavy lint, fan blade clearance check. Capacitor replacement is licensed-tech work — even with power off, the capacitor stores hazardous voltage and rotor windings can re-induce a charge after bleed. Anything refrigerant-side — recovery, leak repair, brazing, recharge — requires a tech with EPA Section 608 certification under federal law (Clean Air Act §608, 40 CFR Part 82, Subpart F). Sealed-system work is not DIY.
South Florida-specific failure modes
- Salt-air pinhole leaks at the brazed joints. Coastal heat pumps lose refrigerant through pinholes in copper that rusted from salt deposits. Annual fresh-water rinse on the coil and copper extends life noticeably.
- Lightning damage to the controller. In our field experience, Florida summer storm season is hard on heat pump control boards.
- Palm-frond and oak-leaf coil clogging. The coil is a giant lint screen. Quarterly cleaning during pollen and leaf seasons.
- Capacitor failure under heat. 95°F equipment pads kill run capacitors in 4–6 years vs. 8–10 in cooler climates. Cheap part, common failure.
When it's time to replace
A 10+ year AquaCal with a refrigerant leak, a corroded cabinet, and a soft compressor often isn't worth the repair. Newer units typically rate higher COP at AHRI conditions than legacy models — verify the rated COP for the candidate model against the AquaCal data sheet. As a rough rule, if the repair quote crosses 50% of new-unit price, replace. See our pool heater comparison for sizing the next one.
When to call a pro
Refrigerant work is licensed by federal law (EPA Section 608). Diagnosing a leak, recovering refrigerant, brazing a joint, recharging — none of those are DIY. Capacitor and contactor work also requires power-off lockout and licensed-pro handling. In Florida, residential pool repair work is regulated by the DBPR (RP / CPC license categories). Get a pool equipment repair visit scheduled and we'll put a certified tech on it with a flat-rate quote.
Pool heater sizing calculator
Surface area × temperature rise × 12 = required heater output. Surface area drives it — evaporation is where pools lose heat.
84–88°F is the family sweet spot.
South Florida unheated pools bottom out in the low-to-mid 60s.
Gas heater: 200k BTU nameplate
A 19°F rise on 392 sq ft needs ≈ 89,000 BTU/hr of output (≈ 109k input at ~82% efficiency). Oversizing a gas heater is fine — it just reaches temperature faster. Undersizing means it runs forever on cold weekends. Heat pumps are rated differently (typically 110k–140k BTU output) and heat slower but far cheaper per degree — the right call for set-and-hold temperature in South Florida; gas wins for fast weekend heat-ups.
Reference sizing for an uncovered residential pool with typical wind exposure, per manufacturer surface-area charts. A solar cover cuts the real load dramatically. Final sizing and gas-line capacity are the installer's responsibility.
Frequently asked questions
Check two things first, because they are the homeowner-fixable causes: low water flow (the unit needs roughly 30 GPM, so clean the filter and check valve positions) and a dirty evaporator coil. If flow and the coil are both good and it still short cycles — compressor on for a minute, off for a minute, repeat — the cause is deeper: low refrigerant charge (which means a leak), a failing pressure switch, or a failed reversing valve. That deeper set is refrigerant-tech work, not a homeowner fix.
A thin layer of frost on a 50°F Florida morning is normal — the heat pump is removing heat from the air, and the coil drops below freezing. The defrost cycle clears it every 30–90 minutes depending on conditions. Solid ice that doesn't clear, or ice that builds during warm weather, is broken.
Symptoms: short cycling, weak heating output (5°F/hour or less when manufacturer spec is 10°F+), high-pressure or low-pressure trips, and oily residue on copper joints. Diagnosis requires gauges — and 'just adding refrigerant' without finding the leak is a temporary fix that fails again next month.
That's the reversing valve switching the unit into defrost mode. Compressor and fan keep running, but the outdoor coil briefly becomes the hot side to melt frost. 5–15 minutes is normal. If you're seeing this every few minutes, the defrost sensor or the controller is calling defrost wrong.
8–12 years inland, 6–8 years on the coast within a mile of the ocean. Salt air destroys the outdoor coil and the cabinet faster than the compressor itself wears out. A regular fresh-water rinse adds years.
Yes — coil cleaning is the one homeowner-safe fix on the unit. Kill the power and lock it out, then run a garden hose from inside the cabinet outward, use a soft brush on heavy lint, and check fan blade clearance while you're in there. Stop at the coil: capacitors store hazardous voltage even with power off, and anything refrigerant-side is licensed work.
Roughly 30 GPM, though the exact number is model-dependent. Below that, the low-flow protection trips early and the unit short cycles without warming the pool. Before blaming the heat pump, clean the filter, check valve positions, and look for plumbing restrictions — low flow is one of the two homeowner-checkable causes.
A tech with EPA Section 608 certification — that's federal law under the Clean Air Act (40 CFR Part 82, Subpart F). Refrigerant recovery, leak repair, brazing, and recharge are sealed-system work, never DIY. In Florida, residential pool repair work is also regulated by the DBPR under the RP and CPC license categories.
As a rough rule, when the repair quote crosses 50% of the new-unit price. A 10-plus-year AquaCal with a refrigerant leak, a corroded cabinet, and a soft compressor often isn't worth the repair — and newer units typically rate a higher COP at AHRI conditions than legacy models, so verify the rated COP on the AquaCal data sheet before you decide.
Heat pump still blowing cold?
We repair AquaCal heat pumps across Palm Beach and Broward — refrigerant and electrical work stays with licensed pros.