If you have ever glanced at your thermostat and noticed it has switched to emergency heat on its own, or if you have started to see your electricity bill climb dramatically during a stretch of cold weather and traced it back to your heat pump running in emergency heat mode, you are dealing with one of the more misunderstood situations in residential HVAC. Emergency heat mode exists for a reason, and when it activates correctly it is doing exactly what it was designed to do. But when a heat pump keeps switching to emergency heat repeatedly, or when it seems stuck in that mode without a clear reason, something in the system is not working the way it should. At Whitney Services, we receive calls about this exact situation every heating season, and in this guide we are going to break down exactly what emergency heat mode is, why your heat pump might be defaulting to it, what the consequences are of running in that mode too long, and when the situation calls for professional heat pump repair in Orlando, FL.
What Emergency Heat Mode Actually Is
A heat pump normally heats your home by transferring heat from outdoor air, which is efficient during Central Florida’s mild winters. When it gets very cold, the heat pump may not produce enough heat on its own.
To compensate, most systems have electric resistance strips—called auxiliary or supplemental heat—that engage automatically to help maintain comfort.
Emergency heat mode differs: when selected manually or triggered by a system issue, the heat pump’s outdoor unit is bypassed, and the system relies entirely on the electric strips. This is far less efficient and can cost two to three times more per hour than normal heat pump operation, potentially leading to higher electricity bills for Orlando homeowners.
The Difference Between Auxiliary Heat and Emergency Heat
One of the most common sources of confusion around this topic is the difference between auxiliary heat and emergency heat, because they involve the same physical components but operate in completely different ways.
Auxiliary heat engages automatically and selectively when the heat pump determines that outdoor temperatures are low enough that it needs supplemental help to meet the heating demand. The heat pump continues to run alongside the auxiliary strips, contributing whatever heat it can extract from outdoor air while the strips fill in the gap. The thermostat may display a message such as Aux Heat or Auxiliary when this is happening, which is completely normal. In Central Florida, auxiliary heat engagement is relatively uncommon because temperatures rarely drop to the range where it becomes necessary, but during an extended cold snap it is a normal and expected part of system operation.
Emergency heat, by contrast, shuts down the outdoor heat pump unit entirely and relies solely on the electric resistance strips. The thermostat displays Emergency Heat or EM Heat when this mode is active. Because the heat pump is completely bypassed, the system loses all of its efficiency advantage over straight electric resistance heating.
There are two ways emergency heat mode gets activated. The first is manually, when a homeowner or technician deliberately selects emergency heat mode on the thermostat. This is appropriate in specific situations, primarily when the outdoor heat pump unit is damaged, iced over, or being serviced and needs to be taken offline while the home continues to receive some level of heating. The second is automatically, when the system detects a problem with the outdoor unit that prevents it from operating, and defaults to emergency heat to maintain some level of heating in the home.
When your heat pump keeps switching to emergency heat mode on its own, the automatic activation means the system is detecting something wrong with the outdoor unit or the heat pump’s normal heating function. That automatic switch is the system’s way of telling you it needs attention.
7 Common Reasons Your Heat Pump Switches to Emergency Heat
1. Outdoor Unit Has Lost Power
If the heat pump’s outdoor unit loses power, often due to a tripped breaker, the system defaults to emergency heat. A single reset may restore function, but repeated trips indicate an electrical issue. Call Whitney Services for professional diagnosis to prevent fire hazards or further damage.
2. Reversing Valve Failure
The reversing valve controls whether the heat pump is in heating or cooling mode. A stuck or failing valve can prevent proper heating, causing the system to rely on emergency heat. Valve replacement is a complex repair that requires a licensed HVAC technician to handle refrigerant safely.
3. Low Refrigerant Charge
Low refrigerant reduces heating efficiency and may trigger emergency heat. This always indicates a leak that must be repaired before recharging. Signs include reduced heating, ice on refrigerant lines, or hissing sounds. Whitney Services uses professional leak detection to fix the root cause.
4. Frozen Outdoor Unit
Ice buildup on the outdoor coil can block heat transfer. This is often caused by a malfunctioning defrost cycle or refrigerant issues. Do not chip ice off the coil as it can damage the fins. Gently pouring lukewarm water may help temporarily, but a professional inspection is recommended.
5. Compressor Failure
The compressor circulates refrigerant and is vital to heat pump operation. A failed compressor forces the system to switch to emergency heat. Replacement is expensive, and for older units, a full system replacement may be more economical. Whitney Services provides guidance on repair versus replacement.
6. Electrical Component Failures
Capacitors and contactors in the outdoor unit can fail, preventing the system from starting and forcing emergency heat. Both components are commonly stocked on service vehicles so repairs are often completed on the first visit.
7. Thermostat Problems
A malfunctioning, misconfigured, or incorrectly wired thermostat can trigger emergency heat. Accidental manual activation, smart thermostat misconfiguration, or internal component failure are common causes. Technicians test the system with and without the thermostat to pinpoint the source.
The Cost of Running in Emergency Heat Mode Too Long
Homeowners who find their heat pump has been running in emergency heat mode for a long time are often surprised by higher electricity bills. Normal heat pump operation moves two to four units of heat for every unit of electricity used, making it efficient in Central Florida’s mild winters.
Emergency heat mode relies entirely on electric resistance strips, which produce one unit of heat per unit of electricity. This makes operating costs two to four times higher. A typical Orlando home that spends $40 to $60 a month on heating could see bills rise to $120 to $200 or more during prolonged emergency heat use.
Prompt diagnosis and repair of the underlying issue is financially important, not just for comfort, because it prevents excessive energy costs while keeping the home warm.
What to Do When Your Heat Pump Switches to Emergency Heat
If you notice your heat pump has switched to emergency heat, here is a practical sequence of steps to follow before calling for service:
Check whether emergency heat was accidentally activated manually on the thermostat. Some thermostats have an emergency heat toggle that is easy to activate inadvertently. If the thermostat is set to emergency heat manually, switch it back to normal heat and observe whether the outdoor unit starts and the system returns to normal operation.
Check the circuit breaker for the outdoor unit. If it is tripped, reset it once and watch whether the outdoor unit starts normally. If it trips again, do not reset it and proceed to calling Whitney Services.
Check the outdoor unit visually from a safe distance. Look for obvious signs of heavy ice buildup, physical damage, or unusual conditions. Do not attempt to service the unit yourself.
Listen for whether the outdoor unit is attempting to start, making unusual sounds, or is completely silent and still. This information is useful to relay to the technician when you call.
Note how long the system has been in emergency heat mode and whether the switch happened suddenly or gradually, and whether it coincides with any change in outdoor temperature, recent electrical events, or any unusual sounds or performance changes you may have noticed.
Contact Whitney Services with this information and we will help you determine the appropriate urgency of the service call and dispatch a technician equipped for the most likely causes based on your description.
When Emergency Heat Is the Correct Setting
It is worth clarifying that there are situations where manually selecting emergency heat mode is appropriate and correct. If the outdoor unit has been physically damaged, for instance by debris impact or flooding, running the heat pump could cause further damage and emergency heat should be manually selected to keep the home warm while repairs are arranged. If the outdoor unit is being serviced and needs to remain offline, emergency heat keeps the home comfortable during the service window. If a technician has diagnosed a specific problem with the outdoor unit and advises using emergency heat temporarily, that is appropriate short-term use of the mode.
What is not appropriate is running in emergency heat mode as a permanent solution to an undiagnosed problem. Emergency heat is a temporary backup, not a substitute for a functioning heat pump. Every day the system runs in emergency heat mode unnecessarily is a day you are paying two to four times more for heating than you should be.
Why Whitney Services Is Orlando's Heat Pump Repair Specialist
When your heat pump keeps switching to emergency heat, you need a team that can diagnose the root cause accurately and resolve it efficiently rather than applying a temporary fix that sends you back to the same situation in a few weeks. Whitney Services technicians are trained in comprehensive HVAC diagnostics and carry the tools, testing equipment, and common repair parts needed to address the most frequent causes of emergency heat mode activation on the first visit whenever possible.
We serve homeowners across the Greater Orlando area with licensed, insured, and experienced heat pump repair technicians who understand the specific demands that Florida’s climate places on heating and cooling systems. Every service call begins with an honest diagnosis, and every repair recommendation comes with a clear explanation of what the problem is, why it happened, and what the repair will accomplish. We never recommend unnecessary work, and we never leave a job without confirming that the system is operating correctly.
If your heat pump is switching to emergency heat and you are ready to resolve the underlying issue rather than watch your electricity bill climb, contact Whitney Services today and let us get your system back to efficient, reliable operation.
Frequently Asked Questions
Is it safe to run my heat pump in emergency heat mode while I wait for repair?
Yes, running in emergency heat mode is generally safe from a mechanical standpoint. The electric resistance strips are a straightforward and reliable heating method, and using them while you wait for a repair appointment will not cause additional damage to the system. The primary concern with extended emergency heat operation is cost rather than safety. Because emergency heat is significantly more expensive to run than normal heat pump operation, it is worth scheduling a repair promptly rather than allowing the situation to continue indefinitely. If the reason for the emergency heat activation involves a suspected electrical fault, gas smell, or carbon monoxide concern, those situations require immediate professional attention regardless of whether the heating itself is working.
How do I know if my heat pump is in auxiliary heat mode versus emergency heat mode?
Most modern thermostats display a clear indication when each mode is active. Auxiliary heat mode, which is normal and expected during very cold weather, is typically indicated by a message that reads Aux, Auxiliary, or Aux Heat on the thermostat display. Emergency heat mode, which is a more significant situation, is typically indicated by a message that reads Em Heat, Emergency Heat, or a similar designation, and is often accompanied by an indicator light. If your thermostat does not clearly differentiate between the two, consult the thermostat’s manual or contact Whitney Services and we can help you interpret what your specific thermostat is showing.
Can a thermostat be the reason my heat pump keeps going into emergency heat?
Yes. A malfunctioning thermostat, an improperly configured smart thermostat, or an accidentally activated emergency heat setting are all common causes of unintended emergency heat operation. Before concluding that there is a problem with the heat pump itself, it is worth checking that the thermostat has not been manually set to emergency heat and that any smart thermostat programming is correctly configured for a heat pump system. Whitney Services technicians routinely check thermostat configuration and wiring as part of any heat pump diagnostic call, and thermostat issues are among the simpler and less expensive causes of emergency heat activation to resolve.
How much more does it cost to run in emergency heat versus normal heat pump operation?
Electric resistance heating, which is what emergency heat mode uses exclusively, costs roughly two to four times more per hour of heating output than a heat pump operating in its normal heating mode. The exact multiplier depends on your specific system’s efficiency rating, current electricity rates, and outdoor temperature conditions. For a practical example, if your heat pump costs you $50 in electricity for a month of typical winter heating, running that same system in emergency heat mode for the same period might cost $100 to $200. Extended emergency heat operation during an Orlando cold snap can add several hundred dollars to a monthly electricity bill compared to normal heat pump operation.
What is the most common reason heat pumps switch to emergency heat in Orlando?
Based on the service calls Whitney Services responds to each heating season, the most common causes of automatic emergency heat activation in the Orlando area are a tripped circuit breaker to the outdoor unit, a failed capacitor preventing the outdoor unit from starting, refrigerant issues that prevent the heat pump from meeting the heating demand, and reversing valve problems that prevent the system from operating correctly in heating mode. Of these, capacitor failure and tripped breakers are the most frequently encountered and also the most straightforward to diagnose and resolve. Refrigerant and reversing valve issues are more complex and require more extensive diagnosis and repair work, but all four of these causes are ones that Whitney Services technicians encounter and resolve regularly.
