Failing/seizing heat pump condenser motor

Over the weekend, our heat pump condenser motor started going out. We first noticed it Saturday afternoon, but I was able to scroll back and see it started failing as early as the day before.

Here’s what it looks like:

Versus a normal run:

This is an 11yo unit, and rather than spend $1k or so to fix, we’ll be replacing the entire system.

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Hey @NJHaley - thanks for sharing (and sorry about the heat pump!)
Would love to pass this along to Data Science to see if it’s of use to them, do we have permission to view your data?

Of course, @JustinAtSense, if there’s anything else you need, let me know!

I looked back further than 24hrs prior and couldn’t find another instance, but there may be other clues I can’t see. If I’d seen the original failure cycle, it might’ve saved us the day waiting for the repair man to come and inside temps close to 90*.

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before spending thousand+ dollars it would be not a bad choice to replace the starting capacitor of the condensor motor. Normally those things are easily accessible. They should have a clear rating printed on it.
They have many shapes, forms & sizes but in general look like this

What I would do:
Turn breaker off of condensor unit.
Take pictures before you take it off.
Take the capacitor to a HVAC & refrigeration part store.
They should have a complete assortment and should be able to help you with a compatible replacement unit.
An new capacitor should set you back $10-$30.
If that didn’t work, you could consider your original plan by replacing the whole unit.
I have gotten so many units back to work by just replacing the starting capacitors.
Even 30 year old units!


I agree, and we’re leaning towards just fixing it. As of this morning, I think it’s more likely to be the motor. I just fired it up and watched it struggle to turn. I tapped it a bunch like you would a car’s starter motor and it was able to turn over and get going.

Our limitation right now is time and convenience - we have a 1mo old and it’s pretty darn hot out, not something we want to roll the dice with.

I’ve found that motors are not even close to $1k, but I guess I’m concerned about a shop having one in stock.

The capacitor is the aid to help the motor start. That is it one and only function.
The way you describe the motor struggling to start up imo could be > 80% fixed by replacing the capacitor

Just be careful with the capacitor. It carries a high voltage and should be discharged before you touch it.

I replaced mine a few years ago, just as preventative maintenance. I have the old one as a spare.


Take the connectors off and short the pins with a screwdriver.
Safety first

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Tech came out and reconfirmed the capacitor was OK. We hemmed and hawed a bit but ultimately decided to replace the whole unit. Moving up to a 2-stage 16.5 SEER because that’s all that was available, really.

$1k for a new motor on an 11yr old unit that runs non-stop from may to October vs a new system that we can have installed tomorrow was a tough decision, especially since it’s likely we’ll be replacing the roof this winter, too.


Had an 11 year old Carrier Puron System.

It would go out annually for the last 5 years - Friday night on start of 3 day holiday weekend. Either Memorial Day, July 4th or Labor Day. I would dread upcoming holidays.

2 or 3 times was Capacitor. Purchased 2 spare so that if course never happened again.

I want to say variable motor went out in 2014 but was covered by 10 year parts warranty.

Original unit finally died Labor Day weekend 2017. Multiple repair companies came out. All agreed entire system needed replacing saying it was 2004 unit. Said the compressor was shot. Quotes ran $7k - $9k.

Had a private individual replace the compressor (which no one else wanted to do). All the others said it wasn’t cost effective.

Now has run 4 years without a hiccup.

Learned a valuable lesson.


Just curious: what was the cost of the compressor replacement? In line with the 7-9K quotes?

Inline? Hardly. It’s was around 10% iirc. Made me realize there is an incredible markup on the equipment and most of the price goes into labor for pump and air handler.

I would point out this was done by an independent individual. Not a company win business to sell me a new Carrier, Lennox or Trane setup.

I was quoted $16K to replace a 4 ton AC unit that I could buy for about $4K. I don’t think they wanted the work.

The replacement (5T) system was about $12.5K, fwiw.

Quick follow up, @JustinAtSense (or anyone else) what’s the consensus on the new appliance - should I delete the old model and wait for it to learn this one, or expect it to eventually meld with this one more fully?

Sense is picking it up, but not the whole appliance. Seems to be missing about 1500w during the run.

So, it sounds like Sense is detecting one component of the Heat Pump. I would personally keep an eye on it over the next weeks and see if accuracy improves or Sense has detected an additional component. If not, I’d recommend deleting the device and waiting for a more accurate detection.

Yes, after a bit more time it seems the other 1500w is the second stage fan. I’ll keep an eye on it.

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