Back-and-Forth from Heat to AC - Around Town Plumbing and Heating

This time of year you may find it difficult to regulate the temperature in your home. During the day you may need to turn on your air conditioner, but find it’s too cool for sleeping. One day a snow squall, next day it’s 70 degrees. Many homeowners switch back and forth between the heating and cooling system when fall or spring brings warm days and cool nights.

But will this cause AC damage? Generally, switching back and fourth between heating and cooling modes won’t cause any problems. However, sometimes switching back and forth can cause your system to shut off. If you “short-cycle” the air conditioner, it can cause the fuse or circuit breaker to trip for the outdoor condensing unit.

This is a mistake many people make. When the unit is in the cooling mode and the thermostat is calling for cooling, the outdoor unit is on. If you adjust your set point temperature higher to shut it off and then immediately dial the set point temperature lower it would call for cooling again and cause the compressor to lock-up.

The reverse is also true. Should the cooling unit finish a cycle and shut down and you immediately go to the thermostat and set it lower, the equipment will attempt to come back on but the compressor will probably lock-up because the pressure has not equalized in the system.

When a compressor locks up during high pressure start up conditions, it will draw a very high amp rate. This can cause a breaker or fuse to blow. Some units have built-in “Anti Short-Cycle” timers. Some digital thermostats have built-in time delays to prevent this from happening.

If your system shuts off, first try checking the fuses or breakers. You should also check the outdoor disconnect for your unit. Some have a separate breaker.

You should get in the habit of letting your thermostat set in the OFF position for at least 5 minutes after it shuts down, before starting another cycle. This allows the refrigerant pressure in the system to equalize.

Should your system shut down and you have checked the breakers or your fuses and that isn’t the issue, you should then call Around Town at 635-5515.