Contactor Pitting, Inrush Mode, and the Health of Your HVAC System

Why is it so urgent when your technician tells you about pitting on your contactors?

HVAC Service & Repair


One way to maximize the life expectancy of an HVAC compressor is to minimize its operation time in the inrush amperage mode. Inrush mode, in HVAC systems and other electronic devices, is the momentary burst of current that flows into the device’s system, causing it to start. Think of starting a car engine- the initial start takes more gasoline, and puts more pressure on the car, than leaving it running for a short period of time. If your vehicle used as much gas to run regularly as it does to start, you would use more gas in the long run and put unnecessary pressure on your vehicle.

This is what it’s like to keep your HVAC compressor running in inrush mode. When a compressor develops pitted contacts, or contacts that have indentations and damage to the metal, this can require the compressor to operate in inrush mode longer. The inrush amperage is near seven times that of the running amperage, placing an inrush running system, at times, over 100 amps. The longer your compressor runs in inrush mode, the more damage will likely be caused to your system.

A visual check will show the pitting in your system’s contactors, and the tech should recommend a contactor change-out to prevent a continuous problem to the compressor windings. For answers to more of your HVAC questions, or to set up an appointment with one of our technicians, call Pleune Service at 800.447.6907.


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