Underside of the top panel of the heat pump exposed

DIY: Replacing the Fan on a Heat Pump 1


At 8:19 PM on December 30, 2015, I received the following text from Jim, our next-door neighbor at our cabin in East Wenatchee:

Steve, we’re at the river and your heat pump fan just broke so fan is hitting shroud. I tried to wedge to balance but no luck so I pulled breaker. I’m worried about freezing its 25 here. You around? Is there a way to turn off your heat pump and still heat, you have wireless thermostat that will let you make change remotely?

Unfortunately, I’d silenced my phone and put it away because we had family visiting for the holiday and we were watching a movie. I didn’t see the text until the following morning (which was yesterday), the morning of New Year’s Eve. I was lucky that Jim heard the fan hitting something inside the heat pump tower and pulled the breaker — he likely saved me having to replace a $200 fan motor (thanks, Jim). Jim was also right to be concerned. Temperatures out near the cabin had been in the low single-digits overnight, and the highs hadn’t been above freezing in some time. If the temperature inside the cabin dropped below freezing for too long, the water stored inside the plumbing’s copper pipes would freeze, expand, and rupture the pipes — causing serious damage. Search online for some “burst frozen pipes” photos. It’s not pretty. Here’s an especially bad one:

Frozen pipes can cause a serious mess

Frozen pipes can cause a serious mess

Because we don’t have natural gas out at the cabin, my HVAC system is a traditional Lennox heat pump setup with a single-stage “auxiliary” electric heat backup feature — which is supposed to kick in if the heat pump stops working (or when it’s too cold outside for the heat pump to efficiently handle the heat exchange and generate warmth). But to make the problem worse, the Internet at the cabin was down, so I couldn’t remotely connect to the ecobee thermostat there to make sure the AUX heat was running.

I texted Jim back, thanking him for the heads up, and asked if he’d mind sending me some photos so I could take a guess at what happened. Here’s what he sent me:

Damage to the top of my heat pump

Damage to the top of my heat pump

Close-up of the damage

Close-up of the damage

The photos show that the center section of the heat pump’s top panel had actually sheered, causing one side of the fan to drop. Those four nuts are what hold the fan motor to the top panel, so my guess is that one of them became loose over time, which caused the fan to wobble as it spun, which made things more loose, until eventually it wobbled so badly that it bent and tore the metal.

But I could speculate as to the cause later. Right now, I needed new parts to fix it.

It was the morning of New Year’s eve, and I had a 2.5 hour drive ahead of me… to a town that probably didn’t have the parts I needed. I keep all the model and serial numbers for my major appliances in a Google Spreadsheet, which really came in handy. I called a local supply house, gave them my model number, and asked if they had a replacement top panel and fan (I guessed that the fan probably got dented when it hit whatever Jim described). They had both in stock, so I swung by, picked up a new fan and top panel, and headed east over the mountains.

When I arrived, I was glad to walk into a cabin that was 55F inside — the AUX electric backup heat strips in the furnace had worked, and were keeping the interior of the house from freezing. I disabled the heat pump in the thermostat installation settings, then turned the heat up to 70F and let the AUX heat do its thing. Normally, using electric AUX heating elements in a furnace is an expensive way to heat a house, but because this cabin is within the Douglas County Public Utility District (which operates hydroelectric dams on the Columbia River), electricity at the cabin is the cheapest in the country at only 2.5 cents per kilowatt-hour (that’s a quarter of what electricity costs in Seattle). So I figured I could afford to heat the cabin a bit while I was there.

Happy to find no burst pipes, I got to work outside right away. Jim had already pulled the fuses for me:

Heat pump fuses removed

Heat pump fuses removed

I still threw the breaker inside (you can never be too careful with 220 Volts). The bit driver extension (part 931009) on my Leatherman Wave multi-tool happens to have a 1/4″ socket on the end… which is the perfect size for removing sheet metal screws in heat pumps. I removed all seven screws and flipped to top panel over, exposing the fan:

Underside of the top panel of the heat pump exposed

Underside of the top panel of the heat pump exposed

Next, I took photos of the fans wires, so I’d know which wire went to the contacter, the capacitor, and the control board. The brown wire went to the capacitor:

Brown wire to the capacitor

Brown wire to the capacitor

The white wire went to the contacter:

White wire to the contacter

White wire to the contacter

And the black wire to the FAN terminal on the control board:

Black wire to the FAN terminal on the control board

Black wire to the FAN terminal on the control board

Once I knew how everything went back together, it was easy to pull the spade connectors off their terminals:

All wires disconnected

All wires disconnected

At this point, I decided to take things inside the garage, where it would be warm enough that I could work without my gloves!

I started by removing the four nuts that hold the fan motor to the top panel. The wire is where Jim had attempted to “farm fix” the panel. It was a valiant attempt, but the panel was too far gone:

Four nuts remove the fan motor

Four nuts remove the fan motor

With the mounting nuts removed, I could flip over the old top panel and set it aside. Notice the missing plastic in the shroud where the fan had taken a chunk out:

Bottom of the damaged top panel

Bottom of the damaged top panel

I took out the metal mounting plate (in the middle of the above photo) and unscrewed the damaged shroud. I hadn’t brought a new shroud with me, so it would have to do until I could order a new one.

Inspecting the fan revealed that it had been bent in multiple places when it gouged the shroud. Fans are relatively cheap ($50), and bent fan blades can cause premature wear on fan motors (over $200), so I was glad I’d brought a new fan along.

Even after removing the set-screw from the collar, the old fan was stuck on the motor shaft. I sprayed some WD-40 down the collar, let it sit for a while… then whacked it with a hammer. The old fan slid off easily:

Old fan removed from motor

Old fan removed from motor

Upon inspecting the fan motor, I could see that the motor had indeed shaken itself loose… but it wasn’t one of the top nuts that had come loose, but one of the four mounting bolts had stripped out from the bottom of the motor. It was 1:00 PM by this time, and I knew local shops would be closing soon for New Year’s Eve. I hurried into town to Motor Mart Electric Motors, a local shop in Wenatchee that specializes in electric motors, including HVAC ones. I was in the store for less than 5 minutes, and was back on my way with a new mounting bolt and a couple of stainless nuts. Here’s the old stripped bolt next to the new one I picked up. You can see on the top left where the old nut had stripped off the bolt and caused that corner of the motor to shake loose:

Original motor mount bolt next to the new one... which is just slightly longer

Original motor mount bolt next to the new one… which is just slightly longer

Before putting everything back together, I cleaned up the motor a bit with some Simple Green:

Cleaned up motor ready for re-installation

Cleaned up motor ready for re-installation

Then I screwed the old shroud to the new top panel and placed the mounting plate in the middle (using my deflated river tube to protect it from scratches):

Old shroud and plate on new top panel

Old shroud and plate on new top panel

I re-ran the wiring conduit through the hold in the shroud and placed the motor on the mounting plate:

Motor ready to be re-attached

Motor ready to be re-attached

I used three of the four original mounting nuts on the top side of the panel, but the new bolt was slightly too long to allow the original nut to tighten all the way down. Rather than hacksaw some of the bolt off, I used a stainless nut to tighten that corner of the motor:

Stainless nut helps keep the longer bolt tighened

Stainless nut helps keep the longer bolt tighened

Then I screwed the original nut on top to finish it off:

All four original nuts tightened down

All four original nuts tightened down

Finally, it was time to install the new fan. I pushed the new fan onto the motor shaft, until the collar was flush with the end of the shaft (which is how the Lennox service manual says to do it). I tightened down the set screw, and gave it a test spin. Hooray! No wobbles!

Shiny new fan mounted.

Shiny new fan mounted.

Back outside, I placed the new top panel and fan assembly onto the heat pump, checked my phone to verify the original wiring, then plug everything in:

Everything put back together

Everything put back together

I replaced the corner panel, plugged the fuses into the outside fuse box, then went inside and turned on the breaker.

I went to the thermostat and tinkered with it until it stopped using AUX heat and called for the heat pump. I saw the lights flicker (that’s good) and heard the familiar hum of the compressor. I went outside to find a happy heat pump… still with plenty of time to clean up my tools, jump in the car, and drive 2.5 hours back to Seattle to celebrate New Year’s Eve with my family (OK… I may have stopped for a Dusty’s Burger in Wenatchee on my way home).

So the next time your heat pump decides to be difficult, don’t call the repairman right away. Armed with your model number, you can search for parts, service manuals, and maybe save yourself a few hundred dollars on a service call — especially on a holiday weekend.

Of course, any HVAC tasks involving Freon needs to be done by a license professional (state laws require that), but for many other repair and replacement tasks, you can safely do it on your own (pull fuses, throw breakers, and test wires before you touch).

It also helps to have friendly and helpful neighbors! 🙂

Questions, comments, or feedback? I’d love to hear from you below!

  • Thanks, Michael. That’s true… but it wouldn’t have been as much fun, and this way I know it’s done right. LOL. 🙂

    Plus… I got a Dusty Burger! 😉