The short answer
Most Carrier Edge thermostat problems in Northern Virginia come down to one of three things: a code on the screen (two dashes, E1, E3, E4 or E5), a locked keypad, or a built-in delay that looks like the system isn’t responding. The delays are normal, the lockout takes five seconds to undo, and each code points at one part.
What the codes mean
Swipe to see all columns →
Swipe to see all columns →
| On the screen | What Carrier’s manuals say | What to do |
|---|---|---|
| Two dashes | It can’t read the room temperature. Everything but the fan shuts off. | Call: it’s the sensor or its wiring |
| E1 | The display and the equipment control module can’t talk over their two-wire connection | Call |
| E3 | It can’t read the outdoor temperature, and dashes show where that number goes | Call |
| E4 | The internal memory failed, and the thermostat gets replaced | Call |
| E5 | The humidity sensor isn’t working, and the thermostat gets replaced | Call |
There’s no E2. If two dashes alternate with a temperature about every 10 seconds, the thermostat is averaging two sensors and one has failed; it keeps running on the one that works. If humidify and dehumidify are both turned off, the humidity reading shows dashes, and that’s normal. Carrier’s owner’s manual says to call your heating and cooling dealer for every code in that table.
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Keypad locked? How to unlock it
A padlock on the screen means the keypad lockout is on. Carrier gives three levels: at level 1 you can change only the temperature, the time and the day; at level 2, only the temperature; level 3 locks everything.
To unlock it, open the door and hold the up and down buttons on the right together for about five seconds. The padlock goes away. It locks itself again two minutes after you stop pressing buttons.
To change the level, open the door and hold the two bottom buttons on the right until 01 shows in the lower right corner. Press up until it reads 04, press the rightmost lower button, then press up until you get the level you want, and press done.
Delays that look like a problem
- A 5-minute compressor timeguard. After the AC or heat pump shuts off, the thermostat waits 5 minutes before it starts it again, to protect the compressor.
- A cycle timer. It limits how many times an hour the system can start: 2, 4 or 6 times, which works out to 30, 15 or 10 minutes between starts.
- To skip both once, press FAN and the up button together. That overrides the timers for one cycle.
Reminders on the screen
The Edge reminds you about three things: CHECK FILTER, CHECK HUM PAD for the humidifier, and CHECK UV LIGHT if you have a UV lamp. The filter and the humidifier pad you can change yourself. Carrier says to have your dealer replace the UV lamp, for safety.
Batteries, power and memory
The Edge doesn’t need batteries. It runs on the system’s 24-volt power, keeps your settings in memory through an outage for as long as it lasts, and keeps the clock running for at least 24 hours. A blank screen means no power is reaching it, which usually means the furnace or air handler is off, its door isn’t closed tight, or the small fuse on its board has blown. Our Carrier code 24 guide covers that fuse.
The factory reset, Option 99
Option 99 on the Edge Thermidistat puts it back to out-of-the-box settings. Carrier’s manual warns that every setting goes: the installer’s setup, your schedule, the clock and the calendar. It’s in the installer’s menu, which opens when you hold FAN for about 10 seconds. At option 99, 99 shows on the left and 10 on the right. Press MODE to move to the 10, then hold the down button while it counts to zero. Fd shows when it’s done. Let go early and it goes back to 10 and nothing resets. Unless we’ve asked you to, leave this one alone: the installer’s setup tells it what equipment it’s running.
When it’s not the thermostat
If the screen looks fine and it’s calling for heat or cooling but nothing happens, the thermostat is often doing its job and the problem is at the equipment. Look at the code light on the furnace. Our list of Carrier furnace codes tells you what it means.
What it costs to have us look
A repair visit starts with a flat $99 diagnostic, and you get the price of the fix before we touch anything. Our Carrier repair page lists what the common repairs cost. Our heating check is $67 per system, through December 31: furnace, heat pump or boiler.
- Carrier thermostat not working
- Thermostat messages and what they mean
- The Carrier Infinity Touch thermostat
- A Nest thermostat on a Carrier system
- Carrier Infinity System Malfunction
- Error codes and warning lights by brand
Every code and setting here comes from Carrier’s own documents: Edge Thermidistat installation instructions and Edge programmable thermostat owner’s manual.
Call or book
Call (703) 997-9757 and tell us the code or message on the screen, or book online from goswiftpro.com/cookiesoffer and a box of warm cookies comes with the visit. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What does E1 mean on a Carrier Edge thermostat?
The display and the equipment control module can’t talk to each other over their two-wire connection. Carrier’s manual says to call your dealer. It’s usually the wiring or a loose connection, sometimes a failed part.
How do I unlock my Carrier Edge thermostat?
Open the door and hold the up and down buttons on the right together for about five seconds. The padlock goes away, and it locks itself again two minutes after you stop pressing buttons.
Why does my Carrier Edge thermostat show two dashes?
It can’t read the room temperature, and it shuts everything off but the fan. If the dashes alternate with a number, one of two sensors failed and it’s running on the other. Either way, it’s a call.
Does the Carrier Edge thermostat have batteries?
No. It runs on the system’s 24-volt power, keeps your settings through an outage, and keeps the clock for at least 24 hours. A blank screen means power isn’t reaching it.
How much does it cost to have a thermostat looked at?
A repair visit starts with a flat $99 diagnostic, and you get the price of the fix before any work starts. Our heating check is $67 per system, through December 31.
