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How do I manually trigger heat pump defrost cycle

Nexusjosh
Community Member

Something akin to this post: https://www.googlenestcommunity.com/t5/Nest-Thermostats/Heatpump-Defrost-cycle/m-p/274887/thread-id/...

There is a lot of ice build up around my coil. How do I trigger defrost to melt the ice manually, since it didn't seem to do it automatically. 

3 REPLIES 3

zoeuvre
Community Specialist
Community Specialist

Hi Nexusjosh, 

 

Thanks for posting. If you notice a significant amount of ice buildup on the coil of your HVAC system, triggering a manual defrost cycle can help melt the ice. Here's a general guide on how to manually initiate a defrost cycle, but please note that the specific steps may vary depending on your HVAC system model:

 

  1. The control board is typically located in the indoor unit or in the outdoor unit of your HVAC system. It may be inside an access panel or behind a removable cover. Consult your HVAC system's user manual or contact the manufacturer for precise instructions on locating the control board.
  2. On the control board, you should find a section dedicated to defrost controls. Look for switches, buttons, or jumper pins labeled "Defrost," "Test," or "Manually Initiate Defrost."
  3. Follow the instructions provided by the manufacturer to manually initiate a defrost cycle. This may involve flipping a switch, pressing a button, or moving a jumper pin to the appropriate position.
  4. Once you've activated the manual defrost mode, the HVAC system should enter a defrost cycle. This cycle typically includes turning off the outdoor unit's compressor while activating the defrost heater to melt the ice on the coil. The fan may continue to run to help distribute warm air during the defrost cycle.
  5. Allow the defrost cycle to run for a sufficient amount of time to ensure the ice has melted. This can vary depending on the severity of the ice buildup. Monitor the coil and ensure that the ice has completely melted before returning the system to normal operation.

 

It's important to note that manually initiating a defrost cycle is a temporary measure to address immediate ice buildup. If you notice frequent or excessive ice buildup, it may indicate an underlying issue with your HVAC system, such as a malfunctioning defrost control, low refrigerant levels, or a faulty sensor. 

 

Let us know how it goes.

 

Best,

Zoe

If I get the same sort of ice buildup again, I'll give this a try, thank you!  The solution was to turn off the system for about 10 hours, then enough ice melted for it to be a non issue.  But it started snowing this morning so it could easily happen again.

zoeuvre
Community Specialist
Community Specialist

Hi there, 

 

Checking back in—have you already tried the steps I suggested above? If so, how did it go? 

 

Thanks,

Zoe