If your pool heater is not working in Jacksonville, you're not alone, and the good news is that a lot of the time the cause is something simple you can spot in a few minutes. Maybe the water feels cold when it should be warm, maybe the unit won't turn on at all, or maybe it runs but never gets the pool up to temperature. This guide walks through the real reasons a heat pump or gas heater quits on the First Coast, the checks you can safely do yourself, and the point where you need to hand it to a tech.
We service both kinds of units all over Duval County, from Mandarin to the beaches, so this is the same logic a tech runs through on a service call. Work top to bottom and you'll usually find the problem.
The two heater types on the First Coast
Most Jacksonville pools run an electric heat pump. They're efficient, they're cheap to operate compared to gas, and they suit our long shoulder seasons where you just want to stretch the swim season a few more weeks on each end. The catch is that a heat pump pulls heat out of the air, so when the air gets cold, its output drops. Northeast Florida runs cooler than South Florida, and our winter cold snaps are exactly when a heat pump struggles most.
Gas heaters are the other type. They're less common here but you'll find them on spas and on pools where the owner wants fast heat on demand regardless of the outside temperature. Gas units heat quicker and don't care how cold the air is, but they have their own failure points around ignition and gas supply. Knowing which one you have tells you which section below matters to you.
Start here: power and the breaker
If the heater is completely dead, no display, no fan, nothing, start at the breaker. Jacksonville summers bring afternoon storms, and a nearby lightning strike or a power surge will trip a breaker without any drama. Go to your panel and look for a breaker that's flipped or sitting in the middle position. Flip it fully off, then back on.
Here's the important part. If it trips again right away, stop. Do not keep resetting it. A breaker that trips the moment you reset it is telling you there's a real fault, and repeatedly forcing it can make things worse or dangerous. That's a call-a-pro line, not a homeowner fix. Same goes for any burnt smell, scorch marks, or buzzing at the panel or the unit.
- Check first: is the breaker tripped? Reset it once.
- Check first: is there a separate disconnect box near the heater, and is it on?
- Call a pro: the breaker trips again immediately, or you smell or see burning.
Low water flow, the number one culprit
A pool heater needs a solid stream of water moving through it to work. Most units have a flow sensor that shuts the heater off when the water isn't moving fast enough, which protects the equipment. When people tell us the heater "won't turn on," low flow is one of the first things we check, and it's often a filter problem.
Our live oaks are beautiful and they are hard on filters. In neighborhoods like Mandarin, Riverside, and Avondale, leaf litter and pollen clog cartridges and load up sand and DE filters fast, which chokes off flow. Check your filter pressure gauge. If it's reading high, your filter is dirty and it's cutting the water your heater needs. Clean or backwash it and see if the heater fires up.
Run through the whole flow path while you're at it:
- Clean a dirty filter or backwash it if the pressure is high.
- Empty the pump and skimmer baskets of leaves and debris.
- Check every valve on the pad is set the way it should be. A valve someone bumped to closed or half-closed will starve the heater.
- Make sure the pump is actually running, and running at a high enough speed. Variable speed pumps set too low won't push enough water to satisfy the flow switch.
Staying on top of filter cleaning and flow is exactly the kind of thing our regular pool maintenance service handles, and it prevents a lot of these no-heat calls before they start.
Heat pump problems: airflow, cold air, and refrigerant
If you've got a heat pump and flow checks out, look at the unit itself. A heat pump breathes air through its coil, so anything blocking that coil kills its ability to make heat. Grass clippings, leaves, mulch piled against the cabinet, or a coil packed with dirt all cut airflow. Give the unit room to breathe and gently rinse the coil fins if they're filthy, being careful not to bend them.
If you live near the water in Ponte Vedra or Jacksonville Beach, salt air is working on that coil year round. Salt corrosion eats aluminum fins and shortens coil life, so beach-area units need more attention here. A corroded coil that's losing efficiency is a tech evaluation, not a rinse-and-done.
Now the cold weather piece. On a genuine Jacksonville cold snap, a heat pump loses efficiency as the air drops toward 50 degrees, and some units have a low ambient cutoff that stops them from running at all in the cold. If it's 45 degrees out and your heat pump won't make heat, that may be the unit behaving exactly as designed rather than a breakdown. Wait for a milder day and test again before you assume it's broken.
One thing to know: if the heat pump runs but blows warmish or normal air instead of noticeably cold air off the top, and the pool never heats, that can point to low refrigerant. Refrigerant is a closed sealed system. It doesn't get "topped off" as routine maintenance, and low refrigerant means there's a leak. That is strictly a licensed tech job with the right gauges and recovery equipment. Don't let anyone tell you to just add a can and move on.
Gas heater problems: ignition, gas, and flame sensor
Gas heaters fail differently. If yours won't fire, first confirm the obvious: the gas supply valve is open, and if it's propane, the tank isn't empty. If the heater tries to ignite and then shuts down, or you see an ignition lockout error, the usual suspects are the ignitor, the flame sensor, or the gas valve. On older units the pilot or hot-surface ignitor wears out, and a flame sensor coated in residue will lock the unit out as a safety measure.
Here's the honest line: checking that the gas is on and the filter is clean is fair game for a homeowner. Anything involving the burner, the gas valve, the ignitor, or the control board is not. Gas and combustion faults carry real risk, and this is where you stop and call us. There's no shame in it, it's just the smart move.
Thermostat, settings, error codes, and scale
Before you assume the worst, check the simple stuff on the control panel. Make sure the heater is set to the right mode. Heat pumps often have separate heat and cool modes, and it's easy to leave one on the wrong setting after summer. Confirm the setpoint is above the current water temp, and if the heater runs on a pool timer, make sure it's actually getting power during the hours you expect heat.
Modern heaters throw error codes on the display, and those codes tell the story. If your unit is flashing a code, write it down before you clear it. When you call, that code helps us walk in knowing whether we're chasing flow, a sensor, high pressure, or a control fault.
One slower-moving problem worth naming is scale. Our water runs on the hard side, and over time mineral scale builds up inside a heat exchanger, insulating it and dropping the heater's output. A unit that used to heat fine and now takes forever can be scaling up. That's a chemistry and equipment issue that ties back to keeping your water balanced, which is a big part of why proper equipment care matters over the life of the heater.
When to call JAX Pool Care
Run the homeowner checks first: reset the breaker once, clean the filter, empty the baskets, confirm your valves and pump speed, check the mode and setpoint, and note any error code. If the heater comes back, great, you saved a service call. If it doesn't, or you hit anything electrical, refrigerant, or gas related, that's our cue.
On cost, so you're not walking in blind: a diagnostic visit typically runs somewhere around $85 to $150. Common repairs like a sensor, ignitor, or capacitor often fall in the $150 to $500 range installed. A major heat pump repair such as a compressor can run roughly $800 to $1,800, and when you're that deep, a new heat pump installed in the $3,000 to $6,000 range may be the better long-term call. Every pool and every unit is different, so we'll give you a straight answer after we actually look at it, not before.
We diagnose and fix pool heaters across Duval County and the First Coast, from Orange Park and Fleming Island to San Marco, St. Augustine, and the beaches. You can read more about our pool repair service, and when you're ready, call us at (904) 706-3170 and we'll get your heater looked at and your water warm again.
Frequently Asked Questions
Why is my pool heat pump not heating when it's cold out?
Heat pumps pull warmth from the air, so their output drops as the air gets colder. Below about 50 degrees they slow way down, and on a Jacksonville cold snap they may barely keep up. That's normal physics, not a broken unit. If it's mild out and still not heating, then something is wrong and worth a look.
Can low water flow stop my pool heater from working?
Yes, and it's one of the most common causes we see. A dirty filter, a closed or half-closed valve, a clogged pump basket, or a pump running on too low a speed all cut flow. Most heaters have a flow sensor that shuts the unit down to protect it when water movement drops too low. Clean the filter and check your valves first.
My pool heater breaker keeps tripping. What does that mean?
A breaker that trips once after a summer storm may just be a nuisance trip from a nearby lightning strike. Reset it once. If it trips again right away, stop resetting it. Repeated tripping points to an electrical fault, a failing compressor, or a bad component, and that needs a tech with a meter, not another reset.
How much does pool heater repair cost in Jacksonville?
A diagnostic visit usually runs somewhere around $85 to $150. Common parts like sensors, an ignitor, or a capacitor often land in the $150 to $500 range once installed. A major heat pump repair such as a compressor can run roughly $800 to $1,800, and at that point a new heat pump installed around $3,000 to $6,000 may make more sense. Every pool is different, so treat these as ballparks.
Should I try to fix a gas pool heater myself?
You can safely check the basics: power, gas supply valve open, water flow, and the filter. Anything past that, like the ignitor, flame sensor, gas valve, or control board, is where you stop and call a pro. Gas and combustion problems are not a DIY job. It's not worth the risk to save a service call.