Equipment error code

Rheem code C5

C5 — compressor alert. The control detected abnormal compressor electrical conditions or failed to prove compressor operation.

Equipment: air conditioner
Brand: Rheem
Source checked: 2026-03-01

What this code means

C5 — compressor alert. The control detected abnormal compressor electrical conditions or failed to prove compressor operation.

Source: Rheem RA14 Series Split System — Alert Code Table (AP17885) · checked 2026-03-01

Which models show it

Rheem RA14–RA20 and Ruud heat pumps with compressor protection algorithms.

What is actually happening

Outdoor unit may hum, trip breaker, or stop with C5 stored.

Is it safe to keep running?

Leave off after C5 until diagnosed — compressor damage spreads to line set.

Shut it down when

Breaker trips, burning smell, or loud hum without rotation.

What a homeowner can safely check

Reset breaker once if tripped.
Clear outdoor obstructions.
Note storm or power outage timing.
Replace indoor filter before one test run.

When to stop

Immediate hum on start.
Second breaker trip.

Likely causes ranked

1. Locked or failing compressor
How a tech confirms: LRA test; megger; mechanical verification.
Typical repair: $1,700–$3,400 · HVAC System Replacement cost guide
2. Bad contactor or loose high-voltage
How a tech confirms: Visual pitting; torque and voltage drop checks.
Typical repair: $165–$410 · Air Conditioner Repair cost guide
3. Open compressor windings
How a tech confirms: Ohmmeter tests; compressor or unit swap.
Typical repair: $1,550–$3,100 · HVAC System Replacement cost guide
4. Drive module fault on inverter units
How a tech confirms: OEM diagnostic software.
Typical repair: $625–$1,350 · Air Conditioner Repair cost guide

Is this the end of this unit?

C5 with confirmed dead compressor on mid-age Rheem — outdoor unit replacement usually beats compressor-only on warranty.

How to clear the code

Single power cycle after five minutes; if C5 returns, keep off.

Why clearing is not fixing it: Compressor electrical faults persist through resets.

Which trade to call

Call a licensed hvac contractor who works on air conditioner equipment. Gas, refrigerant, and combustion faults are not general handyman jobs.

More codes from this brand

Symptom guide: Air Conditioner Not Cooling

FAQ

Rheem C5 meaning?

Compressor alert — electrical or mechanical compressor fault.

C5 vs Carrier 84?

Both compressor-class faults — brand-specific service steps apply.

Capacitor cause C5?

Possible — techs rule out caps and wiring before compressor condemnation.

C5 repair costs?

$165–$410 for electrical; $1,550–$3,400 for compressor or unit.

Is C5 covered under warranty?

Depends on registration and install date — have paperwork ready.

Source

Source — Rheem RA14 Series Split System — Alert Code Table (AP17885). Checked 2026-03-01.