HVAC TIP: Check Your Crankcase Heater

Crankcase heater

It would be really hard for me to count the number of times I have come across a tripped breaker or blown fuse due to a failed crankcase heater. 

It makes sense though, a lot of manufacturers don’t provide an auxiliary contact or thermostat to cut its operation when not needed. 

They are exposed to the elements and varying compressor temperatures contribute to the expansion and contraction of the heater. 

What Is a Crankcase Heater?

A crankcase heater is a component in HVAC systems, used to maintain oil temperature above the refrigerant’s saturation point when the system is idle.

This prevents refrigerant migration and oil dilution which can lead to operational issues like unsuccessful compressor start-ups, inadequate lubrication, and liquid slugging.

The heater enhances the HVAC system’s durability and efficiency and should be controlled by a thermostat or pressure switch for optimal operation.

What Does a Crankcase Heater Do?

Crankcase heaters are used to protect the compressor from liquid refrigerant migration during the off cycle and are an important factor in preventing flooded starts. 

In my experience, crankcase heaters are overlooked during preventative maintenance, finding failed or defective heaters can result in creating legitimate work.

Also, if you are experiencing a situation with a tripped breaker, inspecting the crankcase heater is not a bad place to begin troubleshooting.

Fortunately, there is a product that doesn’t require extra controls to regulate heat.

Universal, self-regulated crankcase heaters are available and they fit various compressor sizes. 

Emerson EasyHeat is a great example of this type of heater.  

✋ Keep In Mind: When wiring in a crankcase heater utilizing auxiliary contacts, ensure that the heater is powered on the compressor “off” cycle and not vice versa, a mistake that has been made by several techs.  

🎥 This video demonstrates the steps taken to diagnose a defective crankcase heater

In this video, the above defective heater is replaced

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Gary McCreadie

Gary McCreadie is an HVAC tech, the creator of hvacknowitall.com, the HVAC Know It All Podcast, and owner of McCreadie HVAC & Refrigeration Services

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HVAC Know It All was created by Gary McCreadie, a licensed refrigeration and gas technician, with three goals in mind:
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