Outdoor air temperature and outdoor coil temperature thermistors are out of range. The manual lists this as an event, not a lockout.
Homeowner part this code names: AC coil cleaner.
Search on AmazonOpens an Amazon search for that name. Check the size against your manual. As an Amazon Associate I earn from qualifying purchases.
Carrier 56 means the outdoor air and coil thermistors are out of range. Count 5 short and 6 long. The manual calls it an event. Causes include heating when cooling was called, a coil thermistor clipped in the wrong place, and an outdoor air sensor body touching sheet metal. One listed action is to inspect the outdoor coil for obstructions, with the power off. The reversing valve, if the unit heats in cooling, is technician work. It is not code 55's failed-sensor defrost rule.
Likely causes
- Heating when cooling is demanded
- Coil thermistor not properly attached, or attached in the wrong location
- Outdoor ambient temperature sensor installed so the sensor body touches sheet metal
Safe checks for 56
- With the disconnect and breaker off, look at the outdoor coil for a blockage by debris or ice. The manual's action for this event includes inspecting the outdoor coil for obstructions
- Techniciantroubleshoot the reversing valve if the unit heats when cooling is demanded, confirm the coil thermistor is clipped to the distributor entry tube, and install the outdoor air sensor so it is not touching sheet metal
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
Call a licensed HVAC technician if 56 returns after the outdoor coil is clear, or if the system heats when the thermostat is calling for cooling.
Find a Carrier dealer (official locator, opens in a new tab) ↗Email me this fix
We save your email and this page. Nothing is emailed. We'll only use your email for this request.
Request a filter and maintenance reminder
We save your email, this page, and the interval you pick. Nothing is emailed. We'll only use your email for this request.
Parts & tools for this fix
Taken from this code's causes or steps. A search link opens Amazon results and does not confirm a fit. Check the model number in the manual.
AC and heat pump coil cleaning supplies: guide
In this code: Coil thermistor not properly attached, or attached in the wrong location
See the guide for what to look for when buying one.