Mini-split can't keep house warm when it freezes outside
Ductless mini-split heat pump systems often struggle to maintain a comfortable indoor temperature when outdoor temperatures drop below freezing. This leaves homeowners unable to adequately heat their homes on colder days, resulting in indoor and floor air temperatures dropping significantly despite the equipment running.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Checking temperature by turning the oven off and back on to see the actual readingDid this help you?
- 2Relying on a repair person's assessment or considering appliance replacementDid this help you?
- 3letting the system run longer to see if it normalizes after a defrost cycleDid this help you?
- 4Replacing the unit with a smaller BTU capacityDid this help you?
- 5Adjusting thermostat target setpointsDid this help you?
- 6Changing fan speed settings between auto, low, and highDid this help you?
- 7Posting pictures of thermostat and furnace wiring connections to get troubleshooting helpDid this help you?
- 8Using the broil function to bring the oven up to temperatureDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“My 5 unit / 2 condenser mini split system (Midea white label called Cooper Hunter) put in by the previous owner struggles on colder days.”source ↗
“I can’t really get my house above 66° when the outside temp is < 25°, even with some new windows.”source ↗
“My floor air temp last February was 48°.”source ↗
“I have an ultra 155 that's ignights and stays in idle.”source ↗
“The supply temp slowly rises to about 105 after 15 minutes with a target of 180.”source ↗
“I have a T6 Hydronic Programmable Thermostat, why when setting the temperature does the temperature never reach the desired temperature ?”source ↗
“now we are in heater season, turned on the heat but its not blowing hot air, but room temp air.”source ↗
“i have no idea why its not blowing hot air, sicking for guidance”source ↗
“We can’t seem to get it to remain at our target temperature so it fluctuates and I’m always worries he’s too cold or warm.”source ↗
“The bottom oven will preheat to the appropriate temperature and then, despite the display showing that it's holding the temperature, it will slowly drop over time.”source ↗
Where this came up
People with this problem also raised
- 4Furnace lights up briefly then hums and shuts off
- 4Thermostat doesn't work after opening it up
- 4Why is my thermostat stuck in heating mode with no cooling option?
- 3Why won't my new thermostat turn on the heat?
- 4HVAC contractor installed mismatched heating and cooling parts
- 4Why does my boiler water keep going lukewarm?