The short answer
A mini split that isn’t heating is often doing something normal: defrosting, warming its coil before it blows, or waiting out a three minute restart. Check the mode on the remote, the set temperature, the filters and the outdoor unit for snow or ice. If it blows cold for more than about 15 minutes, shows a code, or the outdoor unit isn’t running at all, it needs a tech. Working right, a mini split heats a Northern Virginia home all winter.
First, the normal stuff
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| What it’s doing | Why | How long |
|---|---|---|
| The head stops blowing, and the outdoor unit goes quiet or steams | A defrost cycle melting frost off the outdoor coil | Up to about 15 minutes |
| The fan won’t start right after you turn on heat | Cold air prevention: the head waits until its coil is warm so it doesn’t blow cold air at you | A few minutes. Pioneer says up to 10 on its Diamante |
| Nothing happens after a mode change or a power blip | A restart delay that protects the compressor | About 3 minutes |
| dF or H1 on the display | Defrost: dF on Samsung, Pioneer and MrCool, H1 on Gree | Normal |
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Want your own number before anyone comes out? The HVAC estimator prices your house in a few questions.
Check these before you call
- The mode. It should say HEAT or show the sun. Auto, Cool, Dry and Fan won’t heat the room the way you expect.
- The set temperature. A few degrees over what the room is now.
- The remote batteries. A dim screen means the head may not be hearing it.
- The filters. Lift the front panel, pull them, rinse them, let them dry.
- The outdoor unit. Clear snow, ice and leaves off it and away from it. Don’t chip ice off the coil.
- The breaker and the disconnect by the outdoor unit. If a breaker trips again, leave it off and call.
- Every head on the same outdoor unit. One outdoor unit can’t heat and cool at the same time. If one head is on cool and another on heat, set them all to heat.
That last one has its own codes: CH07 on an LG, E7 on a Gree and PA on a Pioneer all mean the heads are asking for different modes.
When it’s cold out
Every mini split puts out less heat as it gets colder outside, and each model has a floor. MrCool’s 5th generation DIY heats down to -13°F and its Hyper Heat version to -22°F. Pioneer’s Diamante heats in outdoor temperatures from 5°F to 86°F. Northern Virginia winters rarely get that cold, so a mini split that quits on a 30 degree day has a problem, not a limit. Most mini splits have no backup heat strips, so when the heat pump can’t keep up, nothing else steps in. More on cold mornings in heat pumps in a Virginia winter.
Symptoms, causes and fixes
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| What you see | Usually why | What to do |
|---|---|---|
| Blows cool air in heat mode | Defrost, the wrong mode, or low refrigerant | Wait 15 minutes and check the mode. If it keeps blowing cool, call |
| Runs all day but the room never warms | Dirty filters, a dirty coil, or a head too small for the room | Clean the filters. If one room never keeps up, read a cold room in the house |
| Outdoor unit iced solid and not clearing | Defrost isn’t working, a bad sensor, or water dripping onto it from the roof | Call. Heat pump frozen covers what’s safe to do |
| Outdoor fan runs, but the head blows cold and no frost ever forms | The reversing valve is stuck in cooling (F8 on a Pioneer, U7 on a Gree) | A repair |
| One head heats and another doesn’t | A mode conflict, or that head’s own fault | Set every head to heat, then look up that head’s code |
| Blinking lights or a code on the display | The system found a fault | Look it up in your brand’s guide |
| Nothing at all, no lights | The breaker, the disconnect or the head’s board | Check the breaker once. If it trips again, call |
Codes that usually mean no heat
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| Problem | LG | Samsung | MrCool | Pioneer | Gree |
|---|---|---|---|---|---|
| The indoor and outdoor units aren’t talking | CH05 | 101, 102 | EL 01 | E0 | E6 |
| Low refrigerant or a leak | CH38 | 554, 574 | EL 0C | Fy, Hd | F0 |
| Outdoor fan | CH67 | 458 | EC 07 | EF | Varies by model |
A refrigerant code means a leak to find, not a can of refrigerant to add. A communication code can be a loose wire or a failing board. Brand by brand: Mitsubishi, Carrier, Daikin, Fujitsu, LG, Samsung and MrCool, Pioneer, Gree and Senville. Every code family we’ve written up is on our error codes and warning lights page.
One reset, not ten. Turn the head off with the remote, switch the breaker off for about 5 minutes, then turn it back on. If the same code comes back, write it down with the model number from the label and call. Resetting a fault over and over can hide what it was protecting.
Repair or replace
Most no-heat calls end in a repair. If the system is old enough that a new one makes more sense, it’s $1,500 off a new system, ductless mini split included, and the estimator shows prices with it already taken off. Best mini split brands and ductless mini split cost cover the rest of that decision.
Book it
A mini split visit starts with our $99 diagnostic, and you get the repair price in writing before anything is opened. Call (703) 997-9757 or book a visit online and tell us the brand and the code or what you’re seeing. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Mitsubishi Electric, Carrier, Daikin, Fujitsu, LG, Samsung, MrCool, Pioneer, Gree and Senville are trademarks of their owners.
Questions people ask
Why is my mini split blowing cold air in heat mode?
Most often a defrost cycle, which can stop the warm air for up to about 15 minutes. If it keeps blowing cold after that, check the mode, then call.
How long does it take a mini split to blow warm air?
A few minutes. The head waits until its coil is warm so it doesn’t blow cold air at you. Pioneer says up to 10 minutes on its Diamante.
Do mini splits work in cold weather?
Yes. Each model has a low limit, from 5°F on some to -13°F or lower on cold climate models, and Northern Virginia winters rarely reach them.
Why won’t my mini split heat when another head is cooling?
One outdoor unit can’t heat and cool at the same time. Set every head on that outdoor unit to heat.
Should I reset my mini split if it stops heating?
Turn it off at the breaker for about 5 minutes and back on, once. If it stops again or shows a code, call instead of resetting it over and over.
