Heat Pump Not Heating

Temperatures got into the low 30’s in the Phoenix area early this morning and it’s still very chilly right now! Our phones are currently ringing off the hook with people reporting their heat pump unit is not heating. It’s going to be a busy day for Magic Touch’s service technicians getting clients furnaces & heat pumps working again.

With freeze warnings and temperatures dropping into the low 30°s all week, we’re expecting high call volumes all week.


One of My Gas Furnaces is Not Heating Today!

Ironically, I too woke up to no heat this morning myself. My home is heated by 3 systems – two gas furnaces and one electric heat pump. One of my gas furnaces is not heating but the other furnace and heat pump are working well. I’m headed into my attic to diagnose and repair the one that’s not working once I finish this article. But I digress.


Let’s Discuss a Heat Pump Not Heating

my heat isn't workingI wanted to focus on why a heat pump may not be heating in this article. I’ll write a separate post about gas furnaces not heating later. Maybe even what I found with my own furnace that’s not heating.

Today, I want to focus on heat pumps as sometimes a heat pump not heating doesn’t mean it’s broken. In fact, every year we get calls about heat pumps not heating only to explain to the caller, “that’s normal.” “You’re heat pump is in the defrost cycle and will start heating again in 15-20 minutes.”

How could we possibly know that without looking at the heat pump in question? Well, that has to do with the temperature, time of day, and how heat pumps work. Not to say, this is always the case. Sometimes, a heat pump isn’t heating because it really is malfunctioning. We have a way of determining that too and it all starts with the client’s feedback. Let me explain.


A Heat Pump That’s Not Heating May Just Be in Defrost

I’ve written several articles in the past explaining how a heat pump works, and the heat pump defrost cycle. If you’d like a more detailed explanation, I recommend checking both of those linked articles first.

In this article, I’m simply hoping to save some people from paying for a service call that wasn’t necessary. Finding out the unit you thought was not heating is working as designed as you’re handing over your credit card for the service call is no fun for anyone except Visa!


What is Heat Pump Defrost?

heat pump not heating phoenix azA heat pump compressor is used to provide both heating & cooling. In short, the heat pump is simply running the AC unit in reverse. When the ambient temperature is in the 30°s the coils around the compressor begin to frost up. To prevent the frost from turning to solid ice and impeding operation, the unit automatically initiates a defrost cycle.

While in the defrost cycle, the unit will not provide heat inside your home for 10-20 minutes. In extremely cold weather, this cycle can initiate more than once leading homeowners to believe their heat is not working.

In Phoenix, the defrost cycle typically happens in the very early morning before sunrise and shortly thereafter. Naturally, this makes many people think their heat is not working. This is especially true of people unfamiliar with heat pumps experiencing their first defrost cycle.


How to Tell If Your Heat Pump Isn’t Heating or If It’s in Defrost

How to determine if it’s broken or in defrost:

  • Go look at the outdoor unit (condenser). Is the fan not spinning but you can hear the compressor running? If so, it’s most likely in defrost.
  • If nothing is running outside and there’s no frost or ice on the coils, it’s likely not in defrost. Your heat pump probably isn’t working per manufacturer specifications and needs service.
  • Either way, wait 20 minutes to see if the heat comes back on. If it does, your unit was likely in defrost and has completed the cycle. If nothing was running but it came back on, your heat pump was simply in delay mode. Depending on the thermostat model you have, it may display a message like, “Starting soon,” or “Delay”. 
  • Check for error messages on your thermostat. If it’s just a code, EX. “Error 123” – relay that information to your service company. Most modern heat pumps use these codes to help a service technician diagnose why your heat pump is not working.

Other options:

  • Move to Hawaii where it never gets down to 30°. Okay, I was just checking to see who’s still reading, we have beautiful weather in Phoenix more often than not!

Safety First

If you have a rooftop heat pump, just wait it out for the 20 minutes. If it’s that cold your roof is likely frosted and very slippery also. I’ve personally slid down rooftops and it’s quite scary! Luckily, I’ve been working on roofs for 36 years and managed to catch myself before being injured. Leave it to the pros, it’s not worth killing yourself to save a service call.


You Won’t Deal with No Heat Due to Defrost Often

Luckily, we don’t deal with freezing temperatures in Phoenix, AZ very often. Typically, we’ll experience our heat pumps initiating defrost a few days a year at most. Some years we’ll go through the entire winter without experiencing it at all.

The benefits of modern heat pumps far outweigh the inconvenience of a 20 minute defrost cycle a few times a year. And hey, I’m about to go find out why my gas furnace isn’t heating right now!


Need Help With a Furnace or Heat Pump Not Heating in the Phoenix Area?

Magic Touch Mechanical has been helping Phoenix area homeowners with heating unit repairs for 27 years! With over 3k 5-Star customer reviews online, an A+ rating with the BBB (always!), and more Angi Super Service Awards than any company in Arizona – rest assured you’re in good hands!

We repair heat pumps, furnaces, patio heaters, fireplaces, fire pits and more. Contact us today for guaranteed 5-Star service!



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Magic Touch Mechanical

942 West 1st Avenue
Mesa, AZ 85210
United States (US)
Phone: 4808558789

Heating, Air, Fireplaces & Firepits since 1997!






about the author rich morgan

Author: Rich Morgan, CEO Magic Touch Mechanical & The Fire Place