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Troubleshooting: My Swimming Pool Heat Pump Will Not Start

Troubleshooting: My Swimming Pool Heat Pump Will Not Start

Consumers often come to us at AquaCal for help with their swimming pool heat pumps because we have manufactured, distributed, and serviced heat pumps for over 30 years. Sometimes consumers come to us with a simple problem: “my heat pump won’t run.” In order to address this problem and to help others, we discuss a few tests you can perform on your heat pump before you call your heat pump professional.

  1. Check your power source. Heat pump owners often forget to perform this simple check and jump right to more tedious ones. Make sure your breaker has not tripped and that the disconnect switch of your heat pump (located adjacent to your unit, typically on a wall or a post) is turned on.
  2. Ensure that your heat pump is getting sufficient water flow. Just as a dirty filter and basket can cause your heat pump to run less efficiently (see our article “Why Isn’t My Swimming Pool Heat Pump Heating?“), they can also cause your heat pump to stop altogether. Make sure the valves to your heat pump are completely open and your filter and pump basket are clean. Some heat pump installations require a plumbing by-pass in the piping system so as to comply with the heat pump’s maximum flow recommendations. This by-pass allows some of the total flow of water to be diverted from flowing through the heat pump and return directly to the pool. This by-pass valve, if present, should not be adjusted after the installer has properly set it.
  3. Check your desired water temperature and your actual water temperature. Many heat pumps cannot cool a swimming pool, they can only heat it. Therefore, your heat pump may not operate if your swimming pool temperature is higher than the temperature set on your heat pump’s display. Set your desired water temperature above your actual water temperature and check back later to see if your heat pump is operating.
  4. Check the air temperature. An air-source heat pump can form ice on its evaporator coil if it operates in low air temperatures. This ice can block air inflow and damage the air-source heat pump’s internal components. Some air-source heat pumps are therefore designed to automatically shut off or activate a defrosting system when air temperatures fall below 50°F (10°C).

If these tests yield no results, or if you still feel uncomfortable with your heat pump’s performance, you should call your licensed heat pump professional. Feel free to leave a comment below if you have any questions or concerns regarding issues with your heat pump. We at AquaCal would love to help!

This Post Has 74 Comments
  1. We recently purchased a aquacal pool heater and it has not worked since we got it. Keeps saying LP. The valve has been changed out twice in 2 weeks. Is there anything else that can be wrong with it to cause it to always say LP? We are not happy with product and for the price we paid, we cant go through this any longer. Why have it take up space on our property when it does not work..

  2. Good morning Lisa-

    We will be happy to look into this issue. We need more info to do so. Name, address and phone number, model and serial if available. Who has been doing the work on the unit?

    With this information we will be able to follow up.

  3. Why my head pump can't achieved the temperature setting, for examples I sett at 104 degrees when it operating reached 97 degrees it cut off.pls advice.

    1. Good morning Ray-

      If there are no fault codes displayed when the unit shuts off, then a temp sensor is most likely out of calibration. You would need a technician to rectify this. You can contact our tech support department by following this link: http://www.aquacal.com/contact

      Please feel let us know if there is anything else we can do to help!

  4. I have an aqua cal model tt120a-a ser# 1023945-f03. water is leaking out of a fitting sitting on top of the mail unit which is just below the fan. it has two small wires going to it. with the unit off & the pool pump on, water comes out of this fitting. what is this fitting and can I change it? Is the pool pump too old & will this cost too much. I don't use the pool pump more than twice a year. thanks. I have been trying to call at 800-786-7751 and can not anybody.

  5. I just turned my heat pump on a couple hours ago…. it said LP… I checked all connections… and everything is fine. Then it turns on, but the heating light does not come on!! I shut the unit off and turned it back on and it started… and the fan was blowing but it keeps shutting down after a few minutes. The heat light came on for a few seconds and then the unit shut down again. Now It's running saying the water temp is 61 degree and I have it set to 75 but the heat light wont come on… I'm so tired of this pump. Please help me

    1. Hello Michael,
      An LP code indicates the low pressure switch on the refrigerant circuit has opened. Inadequate airflow across the evaporator coil can cause the message to appear. Other than that, this code will require a qualified service technician. Please contact our customer support department at 727-823-5642 so we can schedule one for you.

      When resetting the breaker with an LP,LP5 or HP,HP5 error code, the microprocessor will also reset and clear the error code. The fan will come on and spin as normal. There is a 4 minute time delay for the compressor to engage. Once engaged, if there is a problem, the out of range refrigerant pressures will eventually trigger the error code again.

  6. During dormant season pump develops issues. This year it doesn't seem to heat although it runs. Beyond the latter issue, it register water temp as 101 when actual temp is in the 60s. Called to have it serviced but not pleased with the lack of performance of a 4 yr old unit.

  7. heat pump does not start. Checked everything: mode = "heat", "pool" selected, set temp > pool temp. there are no error messages, e.g. FLO is not lit. Is there something simple I am overlooking or could check? TropiCal Model 115

    1. Good afternoon Dave-

      Please contact our technical support department at 727.823.5642, they will be able to help you as your unit is analog.

      Thank you!

  8. new heater. set temp to pool on 90. Heater turmed on then one minute later turned off says 79 on display. Water Temp 79. Wont turn back on to heat pool. Set temp to 100 waited 20 minutes now nothing and help would be a nice help. Tech support has been busy for some time now.

    Mark

    1. Good morning Mr. Jacobs,

      Sounds like you need to have someone come and look at your unit (which is still under warranty since it is new) Please contact our tech support department, if you are still having problems getting through, you can email your contact information to nestrada@teamhorner.com and we will have someone contact you directly.

      Thank you!

  9. Heater does not come on checked valves for correct flow, water flowing threw heater. Heater still reads FLO
    Pulled panel wires and connections look good. Heater has power. Please help!

  10. Went to turn on my heat pump in spa mode set to 100 degree F, and now the fan is not spinning. Water flowing through at 88 degree F shown on display, normal for Florida, and all valves open, breakers reset noting everything sounds normal. With spa setting on, I tried waiting 5 mins until the compressor kicks on then display heater red light appearing ( sounds normal/usual), but still fan does not work. Top of fan warm to touch. Everything sounds normal without fan spinning. Aqua cal Model H155.
    Is this a fan motor / capacitor issue, or other problem.? Can you help me problem solve this issue?
    Thanks

      1. Good Afternoon Mr. Shumway,
        Hope you are doing well. There are numerous reasons that could keep your heat pump from starting. The best advice I can give is to contact our Tech Support Department at 727-456-7411 while you are near the machine so that we can troubleshoot this for you.
        Thanks,
        Robert Brown
        Customer & Tech Support.
        AquaCal/AutoPilot

  11. My Aqua Cal seems to be working but the display is blank. Maybe a burnt out bulb? Can’t tell what temp anything is. What do I do?

  12. I have a aquacal heatwave model#100ahdebna and the control panel doesn’t lite up. How can I test university with out the control. I would hate to spend the money and that’s not the issue with unit. I want to make sure unit works before I spend a few hundred dollars on it.
    Is there a way to jump the control board. I’m a plumber I should have necessary tools to perform work
    Thanks

    1. Hello Lazaro,

      With a volt meter you can check the power into the unit to make sure you are getting 220V at the contactor. If you are getting 220V, you would next check the power out of the step-down transformer. You should be getting around 26V (AC). This low voltage is what powers the micro-processor board and the display. If you are not getting 26V you probably have a bad transformer. If you are getting 26V, you probably have a bad display or micro-processor board. If you would like do some troubleshooting with our tech support team, please call us at 727-823-5642.

    1. Hello John,

      Insufficient water flow can cause the “FLO” and “HP” error messages. Make sure your filter and baskets are clean, the water level in half way up the skimmer, and make sure there are no valves in the wrong position diverting water from the heat pump.

  13. We have a Aquacal Heatwave Superquiet, it is roughly 4 years old. I am getting an F5 error code on our display. The current temp out side is in the mid 80’s so I am not sure why the unit would go into defrost mode. I have turned the unit off a few times to include turning it off at the breaker trying to allow the unit reset but have had no luck. Do you have any suggestions?

  14. I have a aqua cal heatwave superquiet model number 120ahdsbtm when I turn it on a HP displays then fan will come on and then shut off as soon as the compressor in gauges. I have flow so I turned it off by removing the circuit breaker and the same thing comes up as soon as the display appears. Any suggestions

    1. Hello Victor,

      If the “HP” message occurs immediately when the unit is powered up, you will probably need a service tech to check the unit. Please call us at 727-823-5642 and we will be happy to assist you.

    1. Hello Diane,

      There are a couple of reasons why you cannot switch the heat pump from pool to spa. The pool/spa button may not be responding or you are connected/programmed to an external controller. Please call us at 727-823-5642 to discuss.

  15. I have a Tropi Cal T115. Just had to replace the fan capacitor and now the display reads OtA. The water temp is 75 and the pump is set to 88. This error will not clear after. Overnight water temp drops to 72 and pump still won’t come on. Please advise

    1. Hi Daniel,

      OtA stands for Over Temperature Alarm, meaning the unit is measuring the water temperature at 110 DEGF. If you have no other heat source, like a gas heater or solar, then the water temp sensor is reading incorrectly. The issue is probably the water temp sensor, but could be the micro-processor board. Please call us at 727-823-5642 and we will be happy to assist you.

  16. This is a new question about a Jandy Lite2 (LG175NG).
    The pilot will stay lit and when I jumper TH to PP-TH the boiler runs fine.
    I have gone through all the testing of the millivolt system and here is where I get stuck/confused.
    At the end of the black TH wire I have 520 millivolt. When I attach the wire to the TH terminal and the test at the terminal I ONLY see 48 millivolts.
    What could be going on here?
    What could be wrong here?
    Thanks for any help.

  17. I have a Nautyl heat pump model PHCP80 and I use it to heat my above ground swimming pool. Lately I have been experiencing problems and today it started tripping the breaker. Wondering if you can help me out with this problem. When I turn it on, it will start normal, then the compressor cuts in, and about 10-15 secs later, the breaker trips. Have you seen the problem before and if so can you help me out?

    Thanks,
    Dion

    1. Hi Dion,

      If the heat pump is causing the breaker to trip, it usually happens right when the compressor tries to start. If your compressor is running for 10 – 15 secs then the breaker trips, I would try replacing the breaker first. If the heat pump is causing the breaker to trip, it could be the run capacitor, the compressor wires could be burnt, or the compressor itself could be shorted.

  18. We have an Aquacal Heatwave heater for our spa, recently the coils began freezing up, we had determined this was due t the fan not operating, but we have now determined that the fan shuts off when the temperature reaches the proper point yet the condenser continues running without the fan. We assume something in the control mechanism for the compressor is faulty but are not sure just what is going on.

  19. We have an aqua cal pool and spa heater and it’s not getting power to it. We are planning to replace the breaker and see if that’s the problem. Is it necessary to replace it with a breaker with a ground wire?

  20. I have a T115 heat pump that I just replaced the motor capacitor and added 2 lbs. of R22 freon (yes it is old analog unit). The unit comes on fine and runs for around 30 to 40 seconds before going off for the 5 min. restart and then it repeats itself. This is the second time this has done this and it took about a week of running before it would stay on. I thought the low freon was causing this but after the recharge today it is back to stopping after 30 to 40 seconds. I live in Lutz, FL. (Tampa).

    1. Hello Leo,
      There are many things that could cause the your analog unit to shut off. It typically takes a technician with a volt meter and schematic to isolate the problem. Please call us at 727-823-5642 with questions or to set up a service call.

  21. I have an older heat pump, aerotemp tempro 2000. Unit ran fine and heated well until one day it would not turn over. It has power, when pump is off says flo (so I’m guessing at leaSt some of the sensors work to throw that code). When pump is on it displays the temp like it normally does, then after about 1-2min (which is how long it used to take for fan and compressor to fire up) instead of firing up a small red light appears on panel in between the orange indicator lights of pool and spa.I did have someone come look at the unit and they said temp sensor and very low on r22, could the low r22 cause this and not put up some kind of error code? I don’t think the temp sensor is bad as it seems to acurrately display the temp of the water passing through unit just the fan and compressor don’t fire up so I get no heating… it did randomly fire up one day, which was a couple of days after I had messed with the unit and apparently left the breaker on, then the next day same thing, wouldn’t fire up.

    Any thoughts or assistance is greatly appreciated!

    Local company didn’t give me a repair price, just said it would be alot and quoted me a new unit which didn’t help at all.

  22. My heat pump the desired temp is at 78 but the temp of the pool per the heater unit is 102. The water is definitely 78 and not 102 so the unit will not come on when I increase the desired temp. What would cause this?

  23. I have an aquacal model 135, the digital controller is not increasing water temperature, it is reading the water temperature in pool, unable to increase temp to 86, can lower but still fan not coming on, please help, I am frustrated since I purchase this heat pump I only use it between 5 to 7 times

  24. Hi,
    Working well since 2012, my Heat Pump Aquacal model 035 deliver me a strange error code.
    This code is “OtA” (Not OTA).
    Yesterday, first day after winter stop, working well (Pool water t°: 66°F, Outside t°: 75°F, Flow ok, Desired t°: 82°F, no additionnal heater)
    Today the pump does’nt start, (no fan) with this code OtA.
    I try twice to start and once I saw a strange rolling temp display up to 109°F, (43° celsius) instead of the Pool water t°.
    What happen?
    is there a service center in France?
    Cordially, Michel from France

    1. Hello Miched,
      OtA stands for “Over Temperature Alarm” meaning the heat pump believes the water temperature is 110 degf. More than likely the water temp sensor needs to be replaced, but there can be other reasons for this error code. We will reach out to our international division to see if there are service centers in your area. They will contact you via email.

      1. Hi,
        Thanks for your quick answer,
        If I have to change the temperature sensor it would be necessary to have a broken plan of the pump, that I can locate the location of this probe and its reference to order it.
        Where can I find it?
        I guess the water temperature sensor is the one which is located on the inlet piping, as I can see it (there is a second sensor on a copper pipe) In the absence of repairman I have to change it myself, but this probe seems sealed, is that correct?
        is there a special procedure to disassemble it?
        Thanks again
        Cordially
        Michel

          1. Hi,

            The sensor is: Aquacal Heat Pump Water Temperature Sensor ECS6105 10K 0HM
            To remove the doubt I inverted the two probes on the electronic board because I found that the Water sensor is the same as the Defrost sensor
            The pump has started so it confirms that it is the water probe that is failing.
            I found a replacement kit that allows to leave the faulty probe in place (to avoid any breakage):
            AquaCal ECS0275 / STK0127 Water Temperature Sensor replacement Kit:
            Just drill a hole
            – Use 11/32″ or 3/8″ drill bit to tap into water inlet line.

            – Snug the hose clamp around the sensor.

            Maybe this information can help somebody when there is no repairman
            Codially
            Michel

  25. my heater says flo but all my valves are set correctly, and filter and basket are both clean, where else could the issue be i only have 2 pipes, one goes in from filter the other comes out of heater to spa/pool and under normal op without using heater, water flows just as it should, i thought maybe it was connected to my salt generator and that the flow sensor was bad but after bypassing the sensor my salt generator shows flow is fine but i still get “flo” on the heaters screen.

  26. I have a whisper quiet unit. First startup this year, no codes, water in is 61, asking for 80. Panel shows proper set point, fan is spinning, red light indicates heat. Every 5 minutes there is a hmm, compressor trying to start??, then nothing. Capacitor problem? Frozen compressor? Next steps for troubleshooting? Thanks.

    1. Hi Jim,

      Hope you are doing well. Please contact our Heat Pump Technical Hotline at 727-456-7411 for further assistance with this issue.
      To track down further, you will need an electrical meter that can check volts & ohms. If you do not have this on hand, you can call 727-823-5642 to set up a service call with customer support.
      Thanks
      Robert Brown
      AquaCal Tech Support

  27. My 12 year old Aerotemp heat pump fan stopped spinning the other day. The fan spins for 3 seconds and then stops. Do I need a new fan motor or just a capacitor.

    Thanks

    1. Hi Bill,

      Hope you are doing well. If the fan starts, then the issue is less likely just a capacitor as that is the capacitor’s only job.
      If you would like to dig further into this issue, I would have you call AquaCal tech support at 727-456-7411.
      Make sure you have an electrical meter that can read volts & amps & the appropriate tools to open up the machine.
      Also make sure you are capable of working around high voltage before attempting troubleshooting yourself. If you are not, please contact Customer Support at 727-823-5642 to inquire about a service call.
      Thanks
      Robert Brown
      AquaCal /Autopilot Tech Support

  28. Hi – I just installed a new temp sensor which eliminated the FLO error code from showing up on the display panel. Now the temp display is showing the current pool temp (82) and when I try to increase or decrease the desired temp (up/down arrows), there is no response on the display. Only the current pool temp showing. Any guidance on this issue? Thanks! Model is T-115.

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