Carrier Air Conditioner Error Code 5

Error code 5 on a Carrier air conditioner means an open circuit has been detected in the compressor power circuit. The control system cannot deliver electricity to the compressor, so the unit will not cool. This fault can be caused by a tripped breaker, blown fuses, a failed contactor, a locked-out high pressure switch, or broken wiring anywhere along the power path to the compressor.

When error code 5 is present, the compressor is not running, so there is no cooling occurring. The system is effectively locked out and cannot operate in this state, which means there is no risk of further damage from continued compressor operation. However, you should not attempt to repeatedly force the system to restart without identifying and fixing the root cause, as this can damage other components.

Repair costs depend on what has failed. Replacing a compressor contactor typically runs in the range of $150 to $350 including labor. Fuse replacement is generally inexpensive at $50 to $150 for a service call. If the open circuit is caused by a failed compressor itself, replacement costs can range from $1,000 to $2,500 or more depending on the unit. A technician diagnosis visit is usually needed first to pinpoint the fault before any cost estimate can be confirmed.

Some steps are safe for a knowledgeable DIYer, such as checking and resetting a tripped circuit breaker or resetting a tripped high pressure switch if you can locate it. However, diagnosing a failed contactor, testing for broken wiring inside the condensing unit, or working around the high-voltage components of the compressor circuit should only be done by a qualified technician. Compressor power circuits carry 240 volts and can cause serious injury if mishandled.

A power reset may temporarily clear the code if the fault was caused by a compressor thermal protector that has since cooled and reset, or if a transient condition triggered the fault. However, if the underlying cause is a tripped high pressure switch, a failed contactor, blown fuses, or damaged wiring, the code will return immediately or within the first cooling cycle. The root cause must be corrected for the fault to stay cleared.