Heat Pump Fan Problems & How to Fix Them

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Here are some symptoms of a failing or broken heat pump fan and tips on how to fix a fan to help you save money.

Since this troubleshooting guide is meant for air-to-air heater pumps, it is worth mentioning that most issues with heat pump fans come from the condenser side of the system because of its location, lack of maintenance, and the impact of whatever the weather can throw at it.

Regular checks on your air-source heat pump system are essential. You are more likely to pick up on things going wrong before they become a disaster in the middle of a freezing spell or the hottest week ever. A quick look and listen check can tell you a lot.

How your heat pump sounds is important. You will always hear the compressor and fan as they kick in and out, delivering heating or cooling, but if a component starts to fail, you may hear it screeching for help. Don't ignore when it is noisy. It will get you back.

It may be a vibration, but again it's a sure sign there's an issue that you should check on.

Branches can drop inside the unit bending the fan blades out of shape or even stopping the motor from running. This can lead to it burning out and needing to be replaced. In any case, the first thing you will notice if the system is either not working at all or not at its usual level.

Many folks will call an HVAC technician straight off, and that's the best thing to do if you're not confident, but if you can do a bit of troubleshooting, there are some things you can check before making the call.

10 things you can check

  1. Check the power is on and the thermostat is set correctly, not off.
  2. Check for physical obstructions, twigs, or ice.
  3. Look for evidence of damage to the wiring; cut, rusted wires, or links. (Ensure power is off.)
  4. Is it possible to turn the fan easily when it's switched off? If it does, your motor may still be useful. (Ensure power is off.)
  5. If the motor seizes or is binding, it will stop the fan or restrict it.
  6. If the fan is slow, not working, or wobbles, the shaft may be out of true, or its bearings are worn out.
  7. Bent or distorted blades can introduce a wobble, which can lead to seizing.
  8. If the fan motor is running very hot, it can mean it's failing. (Ensure power is off.)
  9. It's normal for the fan to be off for several minutes when the compressor goes through a defrost cycle.
  10. Could the unit be on the defrost cycle? If it is and it shouldn't be, it could be an electronics fault.

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Before we tell you how to change your fan motor, there are six things you should consider:

  1. Always switch off the power before you start – always.
  2. Make sure you buy the correct spare parts. The make, model, and date of your unit should ensure you get the right thing and, if you are in any doubt, contact the supplier and talk to an expert. It'll save you a lot of tears later.
  3. Check the parts to ensure they are correct as soon as they arrive.
  4. It's a good idea to take photos or videos as you go if you can't remember which connection goes where.
  5. Ensure to keep all nuts and bolts and screws safely; it saves scrambling around in the grass to find them later.
  6. One last thing – Always switch off the power before you start!

If the fan is not working, changing the fan motor on the condenser side of the system is a relatively easy DIY job. You need a few basic tools and the correct parts.

Using a professional HVAC technician will cost more, but you will have a full warranty on the repair and parts. However, if you can do it yourself, you will save money. If not, contact your local heat pump expert here (and get free quotes)!

How to fix a heat pump

With the correct parts to hand, kill the power to the unit before doing anything. Remove the top of the unit with the fan, disconnect it, and lift it clear. Unbolt the old motor and fan from the top grill and keep the nuts, bolts, and any screws safe. Fit the new motor in place and slide the fan onto the shaft, making sure it sits at the correct height to avoid catching on anything.

It's worth measuring before removing the fan from the old motor to ensure it goes back at the correct level. Secure it in place and tighten the collar onto the shaft securely. Connect the wires and secure them in place with cable ties, and the job's done. Reconnect the power and start it up.

Change the capacitor

While you are in DIY mode, it's a good idea to change the capacitor. They don't have a long life and are cheap ($10) to buy. Always buy one that matches your new motor (the specifications are on the label on the motor) to avoid issues. It's a simple swap over, but make sure that you discharge any power in the unit before you handle it, even after the mains power is off. They're designed to hold a charge.

Uncover the terminals and place the blade of a screwdriver across them to discharge any residual power. Don't touch the metal blade when you are doing this! Then it's safe to handle. Write the date you changed it with a marker for reference.

The other two fans that could give you problems are the central blower in your air handler, which serves your ducted system, and the blower motor in your ductless split system. Because they are inside the house, there's less risk of them failing, but they do. Let's look at each of them.

Split system blower fan

These units last a long time and shouldn't give you any trouble; however, they can fail. Once you've checked all the usual possibilities: the power supply, fuses, the thermostat, the capacitor, broken or corroded leads, then it may be inevitable the fan motor is dead.

If there's a broken link between the condenser unit and the evaporator, the unit will usually flash a warning light. The meaning of the different flashes is in your system hand-book.

If you can't find it, the manufacturer's website will help. If there are no flashing lights, then a new motor is probably needed. Once switched off, you can open it up, disconnect the small control box, and move it out of the way to access the fan motor. It's not a hard job, just fiddly.

Remove the motor, replace it with a new one, and put everything back together again. It should take you less than an hour. While you have the unit open, you should be able to access the fan (it depends on the individual model); while you are in there, it's an excellent opportunity to clean it thoroughly.

The cost of the motor will vary according to the make, model, and size of your unit. If you call an HVAC technician, the labor costs will vary depending on where you live.

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Air handler blower motor

The blower fan unit and motor sit together above the evaporator coil in the air handler unit. It can be a fiddly job if it's in a tight location; they are installed to take up minimum space, which can be a drawback when you need to work on it. Once again, you need to be sure it's the motor that's burned out. Check the capacitor first. If it has failed, which they do, it's an easy, quick, and cheap fix.

Some air handling blowers are driven directly by the motor's shaft, while others (usually commercial units) are belt-driven. Belts can stretch or break, which will cause the fan to run at less than peak efficiency or not at all. They are relatively easy to change. It's vital to get the correct size and type to match your motor.

One quick check you can do, with the power of try and spin the fan. If it spins easily for a while, then slowly comes to a stop, the chances are your motor is fine. On the other hand, if it is stiff to turn or it's jammed solid, the motor is probably dead.

You can remove the blower unit easily, with only a couple of bolts holding it in place. Unplug the electrical connections making sure you know where they go back! Then slide the blower out completely. The motor is quickly released by undoing the retaining bolts and replacing the new one in the same place.

While you have the unit out, it's worth giving the squirrel cage fan a thorough clean because the blades have a curved shape to give maximum thrust, and they tend to catch and hold dust and debris, which affects their efficiency.

Once reassembled, fit the unit back in place and reconnect it. Switch on and test it.

Conclusion

One recurring theme running through each scenario is maintenance or the lack of it. In some cases, the units wear out naturally, but what will make that happen faster is a lack of regular maintenance.

Book an annual service call with a professional HVAC technician and consider a maintenance contract, so you have a cover. However, if you carry out basic cleaning and maintenance regularly, some of these issues will never happen to you, and that's a happy thought.

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