Carrier LC

What does Carrier LC mean?

The compressor has failed to start. Carrier's repair method is to check whether the resistance of the compressor and the resistance to ground are normal; if they are, the outdoor main board may be defective. The code (also shown as Lc on some models) isolates the fault to either the compressor windings or the driving board.

Symptoms

• LC or Lc shown on the indoor unit display
• Compressor will not start
• No cooling or heating output
• Fault tied to compressor or outdoor board

Common causes

• Abnormal compressor winding resistance
• Abnormal resistance to ground at the compressor
• Defective outdoor main board
• Compressor unable to start electrically

Diagnostic steps

1. 01

   Confirm the LC code

   Verify LC (or Lc) on the indoor unit display first.

2. 02

   Check compressor resistance

   Per the manual, check whether the compressor resistance and the resistance to ground are normal.

3. 03

   Evaluate the outdoor board

   If the resistances are normal, the manual indicates the outdoor main board may be defective.

4. 04

   Repair the indicated part

   Correct the compressor issue or replace the outdoor main board as testing shows, then verify the code clears.

When to call a professional

A compressor that will not start can stem from winding faults or a failed driving board, both of which need meter-level testing around high voltage. Have a licensed HVAC technician measure compressor resistance and resistance to ground and decide on board or compressor service. Start-up failures should not be reset repeatedly without diagnosis, so leave LC repairs to a qualified professional.