Heat Pump Frost Ice Buildup. Hi. I noticed that one of my outside heat pump condensing units was laboring throughout the night. This morning I found ice frost buildup on the heat pump condenser fins. I live in Tucson, Az. It has been colder than normal (below freezing) with a bit more moisture in the air than usual as of late.
Can you please tell me what causes this frost ice buildup, and how I go about rectifying it? Does this mean that the condenser pump is shot? I’m originally from the Midwest and have never experienced this before. What should I be doing? Thank you for your help.
Heat Pump Frost Ice Buildup - The Answer
It sounds to me like you have a heat pump. It is normal for frost to build up on heat pumps. I would guess that in Tucson they set the heat pump to defrost cycle times pretty high as it is dry there. If you have a lot of ice build-up on the heat pump then there is a problem. Possibly with the heat pump defrost controls. However, if the heat pump frost problem is just intermittent then everything is working fine. Therefore, it’s defrosting as designed.
Heat Pump Frost Ice Buildup - Defrost Methods
There are different methods of initiating heat pump defrost but by far the most popular method is timed defrost. The heat pump unit will run for an hour and then automatically kick into the defrost cycle for a predetermined amount of time as engineered by the manufacturer in the defrost control circuit. This is all solid-state control by a printed circuit board. Many are the same from manufacturer to manufacturer.
There is no big difference from a Trane to a Goodman to a Carrier to Rheem heat pump as far as defrost controls are concerned. It is all in the heat pump sequence of operation and is controlled by the defrost board. On the heat pump defrost control board there is usually a jumper or dip switch setting where the heat pump defrost times can be changed depending on geographical location and the HVAC technician’s professional opinion.
Sometimes the switch or pins are set for 30 minutes and some of them are set for 120 minutes. It really depends on several factors as to where this switch or pin is set for timed defrost considerations. If this time is not set correctly you can lose efficiency. The heat pump will kick into defrost too soon and that will use the backup source of heat for the heat pump. In most cases, the backup heat is electric. Electric heat is more cost for producing heat than use the refrigeration cycle to produce the heat.
Heat Pump Frost Ice Buildup - Conclusion
Good luck, and remember if you think there is something wrong with the unit then it never hurts to have it checked out by an HVAC pro. It will give you peace of mind. Better a good heat pump check-up by an HVAC Pro can keep you from being cold late at night. See the video below for how a heat pump enters and exits defrost properly.
It makes a noise and then the condenser fan shuts down. You hear a loud humming noise and then it is quiet for a while. Then you see the frost and ice melt off the heat pump unit. Finally, when it exits defrost mode you see the condenser fan motor starts to turn again. Then a little steam from that process.
Heat Pump Frost Ice Buildup
Our heat pump (Goodman) is new, got it in August I think. It has ice halfway up the side and it’s hitting the ground, too. Should I be concerned? It wasn’t like this last time I looked at it a month ago (and it was much colder at that time outside). We live in Montana, maybe we shouldn’t have went with another heat pump when we replaced the unit…
I would call the installing contractor to take a look. Reputable contractors give a 1-year warranty on their work along with the manufacturers warranty. It is likely something is going on with the defrost cycle there and can easily be fixed. Good luck!!
Thanks! I did call them and they said they’ll take a look, that the timing of the defrost cycle might need adjusting.
No problem! Thanks for visiting our site and hope everything turns out good for you.
With temps below 35 f my heat pump a/c could not keep 68 f inside. It appears the electric backup strips were not energized to maintain heat. In Florida N. Brr! What turns backup on? Temps moderating outdoors now. Want to be prepared! Thanks..
It is controlled by your thermostat and the W wire. When the heat pump begins falling back in indoor temperature your back up electric heat should engage via the thermostat and the circuit for the W closing energizing the relay or sequencer for the electric back up heat. If that is all hooked up correctly then you could have a problem with the elctric heat strips themselves. It is high voltage there so I recommend calling an HVAC pro to check that out.