Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Damage from deliberate AC short cycling?

I have a very underpowered car (no names please), and sometimes turn off the air conditioner for an extra boost while driving. To save fuel, I also sometimes control cabin temp with air recycling by turning the AC on and off.

There are plenty of warnings about short-cycle damage to home air conditioners. Does the same apply to automotive AC, or are there protections from compressor/system design or automatic controls/interlocks?


Well, turning the AC off for more power is a wasted hand motion; the car can and does do that itself when it senses the engine needs more power.

As for occasionally, turning it off and recycling the air: unless you are doing this for a long stretch of time, you’re probably just making the ac work harder once you turn it back on.

Like he said, your car shuts off the A/C itself when you tromp on the gas pedal. (The compressor is off though the blower fan still operates.) You need not shut the A/C down manually for extra power.

I tend to use your method myself in moderate weather, maintaining a comfortable cabin temperature. My car is 16 years old and all A/C components are original. So you need not fear damage to your system.

An AC compressor driven by an electric motor can be damaged by “short cycling.” The short cycling results in the pump stopping momentarily and then restarting against the accumulated head pressure. The induction motors were designed to start against no load and reach operating rpm before head pressure is accumulated. i.e., it is the electric motor that suffers in short cycling. In automotive AC system the clutch take most of the beating in short cycling. But, of course, if the high side were running extremely high an extremely short off time with a very good clutch and engine rpm at a high level could damage the compressor. But not likely.

If you mean on/off every few seconds, I wouldn’t do it. But on/off in minutes is not a problem. And you will improve your mpgs, as long as you don’t open the windows.