I have a 3rd gen Nest, a heat pump outside, and an air handler inside.
When I turn on the fan from the Nest, it only runs the air handler inside. That’s how it’s always been.
Is there any way to manually run just the outdoor heat pump fan?
I’ve had this system for years but never thought about it until now. My heat pump has some frost on it, and I just want to run its fan to help melt it. But it looks like I have no way to do that.
That fan is wired to only run when the heat pump is on. You don’t have direct control over it. The defrost cycle is supposed to handle frost buildup automatically.
ingosi said:
That fan is wired to only run when the heat pump is on. You don’t have direct control over it. The defrost cycle is supposed to handle frost buildup automatically.
Thanks for confirming. I was just making sure I wasn’t missing something.
I think my defrost cycle might not be working right. I turned the unit off for a few hours, and most of the frost melted on its own. The house is staying warm, but I’m worried since temps are going to drop to single digits soon.
Try switching your system to cooling mode for a bit. It will pull warm air from inside and help thaw the outdoor unit. I had to do this on an older heat pump before.
Dexter said:
Try switching your system to cooling mode for a bit. It will pull warm air from inside and help thaw the outdoor unit. I had to do this on an older heat pump before.
Good idea, I’ll give that a shot.
The unit was installed in 2018, so it’s still fairly new. First time I’ve seen it have this issue.
You don’t have control over the outdoor fan separately.
That fan’s job is to pull air through the heat pump coils so the system can transfer heat. Running it alone won’t do much to melt frost.
A little frost on the coils is normal since the refrigerant cools before it gets outside, where it picks up heat. As long as air can flow through, it should be fine.
If the frost gets thick, you can turn the system to cooling mode for a bit. That reverses the cycle and pushes warm refrigerant through the outdoor coils to melt any ice.
If this happens a lot, your system might need a defrost cycle adjustment or an additional defrost timer to prevent buildup.
@SophyGenesis
Appreciate the breakdown, that makes sense.
I ran it on AC for a bit and then shut it down. The frost seems to be gone now.
While I was out checking, I noticed the coils have a lot of dirt and buildup. Some areas look fine, but others are pretty clogged. That’s on me for not keeping up with cleaning. Haven’t done it since installation in 2018.
Once the weather improves, I’ll take the cover off and properly clean it. Something I’ve been meaning to do but kept putting off.
@GuardianGuru2
Yeah, clean coils will help in both summer and winter. It should run more efficiently and save you some energy too. Seven years isn’t the worst I’ve heard, so don’t feel too bad about it. Hope it all goes smoothly when you get around to it.
When the heat pump goes into defrost mode, it actually runs in cooling mode for a short time to generate heat on the coils. The outdoor fan stays off to keep the heat from dissipating too fast. Once the frost melts, it switches back to heating mode.