General Assist Technical Reference
AOT36LMADL – 1b Error During Heating
Known defrost-related fault specific to AOT36LMADL
Use this reference when an AOT36LMADL displays a 1b error while operating in heating mode.
Important: The 1b error on AOT36LMADL is not listed in the standard service manual and is different from the 1b fault used on other models, such as an outdoor fan motor fault on some AOT45LJBYL applications.
1. Symptom
| Item | Details |
|---|---|
| Model | AOT36LMADL |
| Fault display | 1b |
| Operating condition | Fault can occur during heating operation. |
2. Cause
The fault is a known defrost control glitch. It is associated with the outdoor control PCB software rather than the normal 1b fault definition used on other product families.
3. Corrective Action
- Reset the system. A reset may clear the fault and restore operation.
- If the fault recurs, replace the outdoor control PCB. A software upgrade was introduced to the outdoor control PCB to address this issue.
- After replacement, recommission the system and confirm normal heating and defrost operation.
Do not diagnose this fault using the 1b definition from another model. For AOT36LMADL, the known 1b condition described here is a defrost-related control issue.
Quick Reference
| 1b on AOT36LMADL | Known defrost-related control glitch during heating. |
| Temporary recovery | Reset the system. |
| Permanent corrective action | Replace the outdoor control PCB with the updated version. |
Technical reference based on the supplied AOT36LMADL service note.