Pool Heater Troubleshooting: Find Your Problem & Fix It
FREE Basic Troubleshooting available
Pool heater acting up? Find your problem fast — by brand, by error code, or by symptom. Or let our Florida heat pump pros diagnose it over the phone, free.
✓ HVAC & EPA 608 Certified | ✓ 30+ Years Experience | ✓ 90-Day Workmanship Warranty
Start Here: 4 Quick Checks That Fix Most Problems
Before anything else, run through these steps. They solve the most common issues in minutes, no tools required.
- Check water flow first. Pump running, filter clean, valves open. Low flow is the #1 no-fire cause.
- Confirm the thermostat is above current water temp. At/below = heater won’t start.
- Reset the breaker. Off, then on. Trips again instantly → stop, deeper fault.
- Heat pumps: check air temp. Below ~50°F they struggle/ice over. Give it time.
Still stuck? Get a free initial diagnosis.
Tell us the symptoms and a tech will call you. No charge.
Troubleshoot by Brand & Error Code
Most heaters show a fault code when something’s wrong. Find your brand for exact code meanings and step-by-step fixes — the fastest route to a precise diagnosis.
GulfStream
Pool Heater Troubleshooting
Don’t see your brand, or no code showing?
We support every brand and model — including discontinued and out-of-warranty units.
Troubleshoot By Symptom
Not sure which part is failing? Match what your heater’s doing to the likely cause, then follow the linked guide.
Heater won’t turn on at all
Power or flow: tripped breaker, blown fuse, low flow, or thermostat below water temp
Work through power and flow first — here’s the full step-by-step for a pool heater that won’t turn on.
Runs but won't heat the water
Flow or sensor: dirty filter, stuck bypass valve, bad temperature sensor, or cold air (heat pumps).
Clean the filter and check flow first — here’s the full guide on why your pool heater won’t heat.
Turns on, then shuts off
Short-cycling: usually low water flow, or a failing pressure or high-limit switch.
Clean the filter first; if it persists, the switch needs testing.
Heat pump blowing cold air / icing
Frost on cold days is normal (defrost cycle); but persistent icing means low refrigerant or a defrost fault.
That’s not a DIY fix — get a technician to take a look.
Flashing an error code
An error code tells you exactly what’s wrong if you know how to look it up.
Jump to Troubleshoot by Brand & Error Code above to find the meaning for each code.
Gas heater?
Gas-specific: pilot light, gas supply, or igniter.
Work through those in order — here’s how to troubleshoot a gas pool heater.
Need your pool heater fixed now?
Schedule a pool heater repair online and our techs will drive out to you.
DIY, Phone Help, and On-Site Repair
Basic Troubleshooting
Tell us what your heater’s doing and we’ll give you our initial diagnosis — free, no cost.
Guided Phone Repair
A tech walks you through the repair over the phone, step by step — cost quoted up front after your free diagnosis.
On-site Repair
Some repairs need hands-on work. Our techs fix pool heaters across Florida and ship parts nationwide.
How to decide which option is best
Not every problem needs a service truck — and not every problem is safe to DIY. Here’s how to choose.
Your situation | Best path | Why |
|---|---|---|
Simple check (filter, breaker, thermostat) | DIY steps above + free basic troubleshooting | Fixable in minutes, no risk |
You're handy but unsure of the exact fix or part | Guided phone repair | A tech walks you through it and confirms the right part |
Electrical/refrigerant fault, or you'd rather not DIY | On-site repair | Safety and warranty — leave it to a pro |
Why Pool Owners Call Medallion Energy
Licensed Pool/Spa Contractor: CPC056806 | EPA 608 Certified | HVAC Certified
✓ EPA 608 & HVAC Certified Technicians
Legally certified to handle refrigerant systems in pool heat pumps.
✓ 30+ Years of Pool Heating Experience
We know pool heating systems inside and out, every major brand, including discontinued models.
✓ Factory-Trained on Major Brands
We carry replacement parts and offer expert pool heater repair for all makes and models.
✓ 90-Day Workmanship Warranty
If the same issue comes back, so do we.
✓ Statewide & National service area
We fix heaters across Florida and throughout the United states
Our Track Record
What Our Customers Are Saying
- "Medallion Energy is the only company in this industry that I will recommend to any and all that I encounter!! Thanks, Jim!! You and Denice are a 5-star operation!! "
- "They say in business you can only have two of these three and must forfeit one: Speed, Price and Quality. The one exception I’ve found is with Medallion Energy. Jim gave us all three!"
- "I would like to acknowledge this company for their exceptional customer service. We found all employees to be professional, friendly and accommodating."
- "Excellent service and now the heater is up and running! Wish all companies operated like Medallion Energy! Five stars and highly recommend. Thank you!"
- "Our pool heater for our complex is up and running fine. Thank you for such a quick response, dedication and concern for customer satisfaction! Its people like you that restore the faith in the business world!"
- "We recommend everyone to use Medallion Energy for all services! Their good work ethic is outstanding and refreshing! Thank you Jim, Denise, and Ken!"
- "This company goes far and above any company I have ever had to deal with...the best all around. Thank you very much Jim and Denise, my daughter and grandsons had a blast because of you and your company."
Denise did a fantastic job helping isolate and identify an electrical issue. She worked directly with me throughout the troubleshooting process, demonstrating professionalism, patience, and a collaborative attitude as we checked various voltages. She provided logical explanations for the readings and offered a well-reasoned theory about the potential cause of the issue. Subsequent investigation confirmed that her speculations were correct. I was very impressed with her technical knowledge, methodical approach, and ability to work through the problem.
Google Review 5/5 Stars — Outstanding Service and Expert Guidance I cannot say enough good things about Medallion Energy. When I ran into an issue with my pool heat pump's control board, the owner, Jim Diroff, reached out to me personally to help work through it. Jim was extremely professional, courteous, and knowledgeable. He walked me step-by-step through troubleshooting the board, which helped us reach a clear conclusion: after 20+ years of faithful service, it was finally time to replace my old pool heater. Because of Jim's exceptional customer service, I am purchasing my new pool heater directly from Medallion Energy and having it shipped to Maryland. If you want honest advice, deep expertise, and a company that truly values its customers, look no further. Highly recommended!
I want to thank Medallion Energy for helping me getting my heat pump working again. The display said "FLO" despite adequate water moving through the system and I was sure that it was the water pressure control switch that needed replacement. After reaching out to them via email they called me back and asked me what was going on. After explaining the issue they agreed that it was most likely the switch and shipped me a new one. It even came with directions on how to replace it. Once replaced I turned the heater on and it is working again. That saved me a huge bill to replace the heater. Thanks Medallion Energy for your help.
AquaComfort stands behind their products and delivers exceptional service. My husband and I could not be more pleased with this company. The service team went above and beyond to fix our concerns even when the warranty was expired.
FAQs
Why is my pool heater running but not heating the water?
Most often a dirty filter or low water flow, a stuck bypass valve, or a thermostat/sensor reading the temperature incorrectly. On heat pumps, air that’s too cold (below ~50°F) also stops effective heating. Clean the filter and confirm strong flow first; if the water still won’t warm, the sensor or bypass is the likely culprit.
Why does my pool heater turn on and then shut off?
Short-cycling like this is usually low water flow tripping a safety switch — start with the filter and valves. A failing pressure/flow switch or a high-limit switch can also cause it. If cleaning the filter doesn’t fix it, the switch should be tested.
How do I reset my pool heater?
Turn the heater off at its breaker, wait about 30 seconds, then switch it back on. Many digital models also have a reset on the control board. If it trips again right away, don’t keep resetting it — that signals an electrical fault that needs diagnosis.
Why is my heat pump blowing cold air?
Heat pumps move heat from the air into your water, so on cold days there may not be enough heat to pull — below roughly 50°F they become much less effective and the coil can ice over. If it’s blowing cold in mild weather, suspect low refrigerant or a defrost-control issue, which needs a technician.
What does the error code on my heater mean?
Each brand uses its own codes. Find your manufacturer in the “Troubleshoot by Brand & Error Code” section above for exact meanings and fixes. If you tell us the code, we can usually interpret it over the phone.
Do you charge for diagnosis?
Basic troubleshooting is free. Call us or request a callback and we’ll give you our initial read at no cost. If you want a technician to guide you through the full repair step by step over the phone (our LIVE troubleshooting service), we quote that cost up front after the free diagnosis, based on the actual problem and any parts needed. No contracts, no surprises.
Should I repair or replace my pool heater?
If your heater is over 10–15 years old, needs frequent repairs, or the repair approaches the cost of a new unit, replacement is often the smarter spend. For a one-off part failure on a newer unit, repair almost always wins. We’ll give you an honest take — see our pool heater replacement page.
Can you help if my heater is discontinued or out of warranty?
Yes. We support every brand and model of heat pump pool heater, including discontinued and out-of-warranty units, and we ship parts nationwide.
Do you offer pool heater repair near me?
We provide phone troubleshooting nationwide and on-site pool heater repair service across Florida — Orlando, Tampa, Miami, Jacksonville, Daytona, and surrounding areas. Call 407-786-0000 to check coverage for your location.
Let's get your pool warm again.
Start with the quick checks above, find your brand’s error codes, or skip straight to expert help. A free diagnosis is one call away.