Most homeowners find out their heat pump is stuck on emergency heat the same way: the house feels fine, and then the power bill lands like a brick. Emergency heat works. That's the trap. It keeps you warm while quietly burning two to three times the electricity your heat pump would have used for the same comfort.
Here's what that little amber light actually means, what it's costing you every day it stays on, and which causes you can rule out yourself before anybody drives to your house.
What emergency heat actually is
A heat pump doesn't create heat. It moves heat from outdoor air into your house, which is why it can deliver several units of heat for every unit of electricity it consumes. That's the whole efficiency story, and it's why heat pumps cut heating costs 30 to 50 percent compared with electric resistance heat.
Emergency heat throws that away. It shuts the compressor out of the loop and heats your air with electric resistance strips in the air handler — essentially a giant toaster. One unit of electricity in, one unit of heat out. No leverage, no efficiency gain, no exception.
That mode exists for one reason: your outdoor unit is down and you still need heat tonight. It is a lifeboat, not a cruise ship. If it's been on for weeks, something on the heat pump repair side of the equation needs attention.
EM HEAT and AUX HEAT are not the same thing
This is where a lot of confusion starts.
- AUX HEAT — the heat pump is running, and the strips are helping. Normal during a deep cold snap, during a defrost cycle, or when you jump the thermostat up five degrees at once. It should turn itself off within a short stretch.
- EM HEAT — the compressor is locked out entirely. The strips are doing 100 percent of the work. Nothing about this is automatic recovery. Somebody or something put the system there.
In Western Washington, where design temperatures across our service area range from 17°F in Olympia to 29°F in Tacoma, a correctly sized heat pump should rarely need much auxiliary help at all. Constant AUX is a warning. Constant EM is an alarm.
What it's costing you
We won't invent a dollar figure for your house — rates, home size, and setpoint all move it. But the direction is not debatable. When the strips carry the whole load, you lose the 30 to 50 percent heating savings the heat pump was delivering, and the difference shows up on the very next PSE or Tacoma Power bill.
| Mode | What's doing the heating | Relative cost |
|---|---|---|
| ModeHeat pump only | What's doing the heatingCompressor moving outdoor heat inside | Relative costLowest |
| ModeHeat pump + brief AUX | What's doing the heatingCompressor, strips assisting | Relative costSlightly higher |
| ModeEM HEAT | What's doing the heatingElectric resistance strips alone | Relative costHighest by a wide margin |
The practical read: a month stuck on emergency heat can cost more than the diagnostic visit that would have ended it in an afternoon. That math is why we tell people not to "ride it out until spring."
Free checks before you call anyone
Run these first. We'd rather you fix it for nothing than pay us to flip a switch.
- Look at the thermostat mode. If it says EM HEAT or Emergency Heat, set it back to HEAT or AUTO. Somebody may have pressed it during a cold snap last winter and never changed it back. This is the single most common cause we find.
- Check the outdoor breaker. Heat pumps have a dedicated 240V breaker plus an outdoor disconnect box near the unit. If either is off or tripped, the compressor can't run and the thermostat falls back to strips.
- Go outside and listen. With the thermostat calling for heat, the outdoor unit should hum and the fan should turn. Total silence is the tell.
- Change the filter. A choked filter can cause the system to underperform badly enough for the thermostat to keep calling for backup.
- Clear the unit. Blackberry vines, fence panels, stacked firewood, a tarp somebody threw over it in November. Give it two feet of clearance on all sides and a clear top.
If the outdoor unit springs back to life after any of those, watch it for a day. If nothing changes, the cause is inside the equipment.
The real causes we find
The outdoor unit isn't running
A failed capacitor, a burned contactor, a seized fan motor, or a tripped high-pressure switch will stop the compressor cold. The thermostat sees no heat arriving, gives up, and leans on the strips. Capacitors and contactors are among the cheapest repairs in this trade; the diagnosis is the part that requires a meter.
Low refrigerant charge
A leak drops capacity long before it stops the system entirely. The heat pump runs, produces lukewarm air, never satisfies the thermostat, and the strips fill the gap on every cycle. Your bill climbs quietly for months. Leak searches and repairs are a real repair, not a top-off — adding refrigerant to a leaking system just funds the leak.
A failed defrost board or sensor
Defrost is normal. Puget Sound's damp air puts frost on outdoor coils all winter, and the system reverses briefly to melt it off — steam and all. When the defrost control or its sensor fails, the unit either never defrosts and ices solid, or gets stuck in defrost and stops producing heat. Either way, backup heat picks up the slack.
Thermostat wiring or configuration
This one shows up after a DIY thermostat swap. Heat pumps use reversing valve wiring (O/B terminals) and separate auxiliary staging. Wire it like a furnace, or configure it as a conventional system, and the thermostat may run strips as its primary heat source without ever telling you. The equipment is fine. The brain is wrong.
A balance point set too high
Smart thermostats let you set the outdoor temperature below which the strips engage. Set at 40°F, they'll engage constantly in a marine climate where heat pumps still work efficiently well into the 20s. Lowering that setting to something appropriate for your address often ends the problem for free.
Repair or replace
Our honest rule hasn't changed. Under 10 years old and the repair costs less than half a replacement? Repair it. Heat pump repairs run $150 to $1,500 in standard markets and $175 to $2,000 in premium markets, and a technician quotes the price before touching anything.
Once a system is 12 to 15 years old, especially if it uses R-22 refrigerant, a four-figure repair usually buys you the wrong thing. Replacement runs $10,000 to $16,000 in standard Puget Sound markets, comes with a 10-year parts and labor warranty, and can qualify for up to $4,400 in PSE rebates when it replaces an existing electric or fossil-fuel system — the exact amount depends on what you're replacing and what you install. Programs change, so we confirm your current eligibility and handle the paperwork. Note that rebates follow the meter, not the county: if Tacoma Power, Seattle City Light, Peninsula Light, or a local mutual bills your electricity, the program is different and we'll tell you which one applies.
If you'd like starting numbers before anyone visits, the instant estimate tool gives you Good, Better, and Best pricing in about 60 seconds. Related reading if the system is producing no heat at all: Heat Pump Not Heating? 7 Causes.
What a stuck-on-EM-heat call looks like
A technician verifies the thermostat mode and configuration, confirms power at the disconnect, checks compressor and fan electricals, reads refrigerant pressures, tests the defrost control, and inspects the strip heater staging. Then you get the finding and the price, in that order, before work starts. Same-day repair when parts are on the truck; a scheduled return if something has to be ordered.
The goal is simple: get your compressor back to doing the heating, and get those strips back to being the lifeboat they were designed to be.
Get it off the strips
Every week on emergency heat is money you don't get back. If your thermostat is showing EM HEAT and the free checks didn't fix it, book an appointment or call (253) 785-4622. Mon–Fri 8–6, same-week scheduling across King, Pierce, and Thurston counties, from the company headquartered right here in Federal Way.