Wondering what's going on in there?
How a heat pump heats, in plain English
A heat pump doesn't burn anything. In winter, it pulls heat from the outdoor air, even cold air, and moves it inside. It's an air conditioner running in reverse.
- Gather heat. The outdoor unit pulls heat from the outdoor air, with a fan and cold coils.
- Move it inside. The compressor pumps a cooling liquid, called refrigerant, through copper pipes. A reversing valve sets the direction: heat in for winter, heat out for summer.
- Blow warm air. The indoor unit's fan pushes the warm air through your vents. Carrier says it's about 85 to 100°F, cooler than a gas furnace's.
- Defrost. In cold, damp weather, frost builds up outside. Lennox says it melts it off for 5 to 15 minutes at a time, and you may see steam.
Backup heat: many heat pumps have electric backup heat for very cold weather or a breakdown. Carrier says to use emergency heat sparingly, because it raises your electric bill.
So a heat pump that blows cold air is usually one of these:
- A setting, or a normal defrost.
- The outdoor unit is blocked, iced up, or has no power.
- A dirty filter, or air that just feels cooler than a furnace's.
- A part only a pro can test: refrigerant, the reversing valve, or a defrost control.
The questions at the top check these in the same order. Same outdoor unit blowing warm air in summer? See an AC blowing warm air. Thermostat acting up? See a thermostat that's not working. Breaker won't stay on? See a breaker that keeps tripping.
AC won't start at all? See our guide to an AC that won't turn on.
Rather not do it yourself? Call an HVAC tech.
That's a fine choice. Maybe you're busy. Maybe you're selling the house and just want it done right. An HVAC tech (a heating and cooling pro) can find out why your heat pump is blowing cold air and fix it.
Most companies charge $75–$250 to come out, and many put that toward the repair. A new compressor costs $800–$3,500.
Find heat pump repair near you
Find heat pump repair near me →Opens Google Maps. We don't ask for your number.
What to say
Calling a pro? Here's what to say.
A few lines to read when they pick up, and the questions to ask before anyone comes out.
Before you call
Say this
Hi. My heat pump is blowing cold air. When's the soonest you can get here? And what's your fee for the visit? Does it go toward the repair?
Always ask
- What's your fee to come out, and does it go toward the repair?
- Will you tell me the full price before you start any work?
- Are you licensed and insured?
Watch out if
- They push a whole new system on the first visit for a small problem.
- They won't give you a price before starting.
- They want to "just add refrigerant" every year without finding the leak.
Feeling pushed to decide on the spot? You can say no and hang up. You owe nothing for a phone call.
Answer up to 5 quick questions. We'll give you the words a pro uses.
Answer the questions →More of a list person?
Common symptoms, causes, tests and costs
Find the row that sounds like your heat pump. The quick test is something you can check yourself in a few minutes.
| What you notice | What it probably is | Quick test | Do it yourself | With a pro | Verdict |
|---|---|---|---|---|---|
| Thermostat on Cool or Off, or the fan on On | A thermostat setting | Look at the mode and the fan setting | Free | Not needed | FIXSee the answer: A thermostat setting |
| Steam or a whoosh outside; cool air for 15 minutes or less | It's defrosting. That's normal | Watch the outdoor unit for steam | Free | Not needed | FIXSee the answer: It's defrosting. That's normal |
| Snow, leaves or debris piled against the outdoor unit | The outdoor unit is blocked | Look at the outdoor unit | Free | Not needed | FIXSee the answer: The outdoor unit is blocked |
| Thick ice that stays after a defrost cycle | Heavy ice: a defrost problem | Look for ice more than ¼ inch thick | Pro job | $90–$650 | CALLSee the answer: Heavy ice: a defrost problem |
| Outdoor unit silent; its breaker or switch box was off | The outdoor unit's power was off | Check its breaker and the switch box | Free | Not needed | FIXSee the answer: The outdoor unit's power was off |
| The outdoor unit's breaker trips again after a reset | The breaker keeps tripping | Reset once and watch | Pro job | $150–$400 | CALLSee the answer: The breaker keeps tripping |
| Power on, but the outdoor unit stays silent | The outdoor unit won't start | Check the power first | Pro job | $100–$3,500 | CALLSee the answer: The outdoor unit won't start |
| Filter gray and clogged; weak, lukewarm air | A dirty filter | Slide out the filter and hold it up to a light | $1–$35 | Not needed | FIXSee the answer: A dirty filter |
| Lukewarm air; the house slowly warms | Heat pump air feels cooler than a furnace's | Feel the air for a few minutes and watch the room temperature | Free | Not needed | FIXSee the answer: Heat pump air feels cooler than a furnace's |
| Outdoor unit runs; air stays cold; house gets colder | A refrigerant, reversing valve or defrost problem | Feel the air for a few minutes after a clean filter | Pro job | $100–$1,000 | CALLSee the answer: A refrigerant, reversing valve or defrost problem |
2026 U.S. averages, rounded. Pro prices include parts and labor. Most companies charge $75–$250 to come out, and many put that toward the repair. Nights, weekends and big cities cost more. See all repair prices
Want proof it's heating?
The 15-minute vent test
This tells you whether it's really heating, or just in a defrost.
- Set the mode to Heat, the fan to Auto, and the temperature 5 degrees above the room.
- Wait 15 minutes. That covers a normal defrost.
- Hold your hand, or a kitchen thermometer, at a vent for a minute.
- Lukewarm to warm, and the room is slowly warming: it's working. Carrier says 85 to 100°F is normal.
- Cold for more than 15 minutes, and the house is getting colder: take the questions at the top.
Not sure it's safe to keep running?
Turn it off right away if…
- You smell burning, or see smoke.
- The breaker trips again after one reset.
- It makes a loud grinding, banging or screeching noise.
- Thick ice stays on the outdoor unit after a defrost.
To turn it off, set the thermostat to Off. Lennox says never to open the heat pump's panels or touch the refrigerant lines. Need heat meanwhile? Carrier says emergency heat can fill in, used sparingly.
Got a big repair quote?
Should you repair it or replace it?
Many heat pump fixes are free: a setting, the filter, or clearing the outdoor unit. HomeAdvisor puts the average repair at about $410. Ask yourself three things:
- Is it a small part? A capacitor or contactor runs about $100–$400. Ask for that test before talk of a compressor.
- Is it under warranty? Ask the company that installed it. The model sticker on the outdoor unit has the date.
- The half rule. A compressor runs about $800–$3,500. If the repair costs more than half the price of a new system, get a replacement price too.
Example: a $200 capacitor on a 5-year-old heat pump is worth doing. A $3,000 compressor on an old one is worth comparing with a new system.
Ran into a word you don't know?
Heat pump words, explained
Read these before you start. The drawings show roughly what each part looks like.
- Heat pump
- A system that moves heat from outdoors in during winter, and from indoors out during summer.
- Outdoor unit
- The big box outside with a fan on top. It gathers heat from the outdoor air.
- Defrost cycle
- A few minutes when the heat pump melts frost off the outdoor unit. You may see steam.
- Heavy ice
- Ice more than ¼ inch thick that stays after a defrost. Not normal.
- Thermostat
- The control on your wall that tells the heat pump when to run.
- Emergency heat (Em Heat)
- A thermostat setting that uses only the backup heat. It costs more to run.
- Air filter
- A flat screen that catches dust before air goes into the indoor unit.
- Switch box (disconnect)
- A box on the wall next to the outdoor unit with a switch or pull-out handle that cuts its power.
- Breaker
- A safety switch in your breaker box. The outdoor and indoor units each have their own.
- Compressor
- The pump in the outdoor unit that moves the refrigerant. The costliest part.
- Refrigerant
- The cooling liquid sealed inside the pipes. It carries the heat.
- Reversing valve
- A valve that switches the heat pump between heating and cooling.
- Capacitor
- A small part that gives the motors a push to start. It can hold a charge, so it's a pro job.
- Contactor
- A switch in the outdoor unit that turns it on when the thermostat calls.
Still have questions?
Questions people ask most
Why is my heat pump blowing cold air in heat mode?
A heat pump blowing cold air in heat mode is often just defrosting, which lasts 5 to 15 minutes. It can also be a setting, a blocked or iced-up outdoor unit, or a dirty filter. The questions at the top check them in order.
Is a heat pump blowing cold air an emergency?
A heat pump blowing cold air is usually not an emergency, but a burning smell or a breaker that keeps tripping is. Then turn the system off at the thermostat and call a pro. Short bursts of cool air during defrost are normal. If it stays cold and the house is cooling down, Carrier says emergency heat can fill in until a pro comes.
Is it normal for a heat pump to blow cool air?
Yes, heat pump air often feels cooler than furnace air. Carrier says heat pump air is about 85 to 100°F, while a gas furnace blows about 120 to 140°F. It can feel cool on your hand while it still heats the house.
How long does a heat pump defrost cycle last?
A heat pump defrost cycle lasts 5 to 15 minutes, Lennox says. It checks for frost every 30 to 90 minutes in heating mode. Steam and a whooshing sound are normal.
Should I use emergency heat?
Carrier says emergency heat can fill in when the outdoor unit isn't working. Use it sparingly, because it raises your electric bill.
Why is my heat pump covered in ice?
Some frost on a heat pump is normal: Carrier says frost under ¼ inch should melt during defrost. Thick ice that stays needs a pro. Don't chip at it.
How do I reset my heat pump?
To reset a heat pump, Carrier says to turn off the thermostat, switch both breakers off, and wait one minute. Switch them back on, wait a few minutes, then set the thermostat to Heat.
Who do I call for a heat pump blowing cold air?
Call a heating and cooling company (an HVAC tech) that works on heat pumps. Lennox says never to open the heat pump's panels or touch the refrigerant lines yourself. Check the thermostat setting, the filter, and the outdoor unit for snow or ice first.
How much does heat pump repair cost?
Heat pump repair averages about $410, HomeAdvisor says. A capacitor runs about $150–$250, a defrost board $200–$650, and a compressor $800–$3,500.
How we built this
The questions follow the order an HVAC tech checks a heat pump that blows cold air: the thermostat, the outdoor unit, its power, then the filter and the air at the vents. Each answer makes some causes more likely and others less likely.
Prices are 2026 national averages from published repair-cost guides, rounded. Your local prices will differ.
- Lennox, heat pump blowing cold air (February 2026)
- Lennox, understanding the heat pump defrost cycle (November 2025)
- Carrier, heat pump not heating (read October 2026)
- HomeAdvisor, heat pump repair cost (June 2026)
- HVAC.com, heat pump repair costs (November 2024)
- Fixr, heat pump repair cost (January 2026)
How we make money: some links go to parts stores that pay us a small commission, and some pro listings pay us when you call them. Verdicts come from the diagnosis, not from who pays more.