Between seasons, you may not be surprised to hear your air conditioner and furnace running on the same day. But is it safe to frequently switch between heat and cool? And what happens when your AC and heater start running at the same time?
Keep reading to learn 4 possible reasons your AC and heater are running at the same time. Then, we’ll answer some common related questions.
Can You Switch from Heat to Air Conditioning on the Same Day?
Switching back and forth from heat to cool is perfectly safe. However, you should make sure that you let your unit complete its cycle before flipping the switch. Once the cycle is over, wait about 5 minutes before switching it from heat to cool, or vice versa. This allows the refrigerant in your system to return to its original pressure.
You know the cycle is complete when the room temperature matches your setting and the “Heat On” or “Cool On” indicator disappears from your thermostat screen. Physically, you will hear the loud machinery shut off, and the air coming from your vents will eventually stop blowing or feel neutral rather than hot or cold.
4 Reasons Your AC and Heater are on at the Same Time
In most cases, your furnace and AC will run at the same time because of an internal issue. Here are some of the most likely causes:
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Incorrect Wiring
If you recently had a new HVAC unit installed, the technicians may have incorrectly wired your new system. This incorrect wiring could be causing your air conditioner and heater to come on at the same time. This may also be the case if you replaced your thermostat recently. To remedy the situation, simply reach out to a trusted HVAC company to schedule an appointment to fix the wiring.
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Faulty Thermostat
Another possible cause could be a faulty thermostat. Over time, the wires in your thermostat can degrade, and the electrical components inside the thermostat may begin to malfunction. In these cases, replacing your thermostat is an easy and inexpensive way to fix your HVAC system.
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Defective Control Board
The control board manages a number of functions, including giving power to both your air conditioner and heating unit. A number of things can cause your control board to become faulty, including power surges, stuck relay switches, and loose wiring. If you suspect your control board is faulty, reach out to Allied Air Conditioning & Heating for professional replacement service.
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Shorting Wires
In some cases, your HVAC system may be malfunctioning because two wires are touching each other and shorting out. This is usually an easy fix. Reach out to Allied Air Conditioning & Heating to fix the wiring issue.
While these four electrical faults explain why the system might be malfunctioning, you may still have concerns about how the furnace and AC are supposed to work together normally.
Related Questions
Here are answers to common questions regarding proper HVAC operation.
Does the furnace control the AC?
No, the furnace does not control the AC. However, they work together through a shared control board and ductwork. Your thermostat signals either the furnace (for heating) or the AC (for cooling) to run, and the furnace’s blower fan is used by both systems to circulate the conditioned air through the same ducts and vents.
Is it bad to switch from heat to AC frequently?
Yes, rapidly switching modes places significant stress on the AC compressor and can cause it to lock up or fail if pressures haven’t equalized. It is standard practice to wait at least 5 minutes before switching from Heat to Cool (or vice versa).
Why does my furnace keep running?
If your fan is set to AUTO but won’t shut off, check the temperature of the air coming out:
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If the air is HOT:
Your furnace is struggling to reach the temperature you set. This is usually caused by a dirty air filter choking the airflow, or it is simply too cold outside for your unit to keep up.
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If the air is COOL:
A safety switch has likely tripped. The fan is running non-stop to cool down the internal components and prevent the system from overheating.
Why does my AC unit keep running?
If your AC runs constantly, it is struggling to move heat out of your house. This is usually due to one of two factors:
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A Physical Problem:
The system is “choked” and cannot breathe. This is caused by a clogged air filter, dirty outdoor coils, or being low on refrigerant.
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The Weather:
On extremely hot days, the heat outside is simply stronger than your AC’s capacity. The unit has to run nonstop just to maintain the current temperature.
Schedule HVAC Repairs
If your heating and cooling system is acting up, Allied Air Conditioning and Heating Corp. is here to help. Our team has extensive experience dealing with malfunctioning HVAC systems. We always inspect your system before starting any repairs so we can diagnose the issue accurately.
We’re proud to offer honest and affordable repair services you can count on.
For over 55 years, we’ve been the most trusted choice for air conditioning repair in Palatine and the surrounding communities. Call us today at (847) 262-3349 to book a repair appointment.
