Weil-McLain A93 Error Code — What It Means
Weil-McLain does not publish a universal A93 error code that applies across all boiler models. Error codes are control-specific and vary between the Ultra, Aqua Balance, CGa, and other series. Your boiler’s manual or the control quick-start guide will list the exact meaning of A93 for your unit. In general, Weil-McLain codes beginning with A often relate to sensor faults, flame-proving issues, or water-level problems, but the exact definition depends on the control board installed on your particular model.
Before assuming a part has failed, consult the boiler data plate for the model number and locate the corresponding manual. Some faults reset from the control after the underlying condition is corrected, so the first step is always to note when the code appeared and whether the boiler was running, heating, or in standby. Do not bypass safety interlocks or attempt a repair without knowing the exact fault definition for your control.
Before You Replace Anything
Technicians sometimes replace the control board when the real problem is a dirty or mispositioned flame sensor or a simple wiring connector that has backed out. Always verify sensor continuity and clean flame-rod ceramic insulators before ordering a new control.
Common Causes
- Model-specific fault definition (~100%) A93 may mean different things on different Weil-McLain controls, so the true cause depends on the exact boiler series and control board installed.
Quick Diagnosis
Answer these to narrow it down fast.
Does your boiler manual or control label list an A93 code and its meaning?
No: The code may not apply to your model. Verify the control type on the data plate and contact Weil-McLain or a service technician with that information.
Does the code reset and stay off after you power-cycle the boiler?
No: The underlying condition is persistent. Check sensors, wiring, and water level as directed by the manual for that code.
Are any other error codes displayed at the same time?
No: Focus diagnostics on the single component or circuit named by A93 in your model's manual.
Step-by-Step Fix
- Turn off power at the boiler service switch and at the circuit breaker.
- Locate the boiler data plate on the jacket and write down the complete model number and the control board part number or name.
- Find the manual for that exact model online at Weil-McLain’s support site or in the printed documentation that came with the boiler.
- Look up code A93 in the fault-code table and note the described fault and corrective action.
- Inspect the named component (sensor, pressure switch, or wiring harness) for damage, corrosion, or loose connectors.
- Test the component according to the manual’s diagnostic steps, using a multimeter to verify continuity or resistance as specified.
- Reset the code from the control panel after correcting the fault, restore power, and monitor for recurrence during the next heating cycle.
Parts Often Needed
| Part | Notes |
|---|---|
| Flame sensor or flame rod | Amazon | Common on many Weil-McLain models when A-series codes relate to flame proving; verify part number from your manual. |
| Water-level or pressure sensor | Amazon | Some controls use A-codes for low-water or pressure faults; match the sensor type to your boiler series. |
When to Call a Pro
Call a licensed boiler technician if you cannot find your model’s manual, if the manual directs you to check gas pressure or flame current, or if the code persists after you have verified wiring and sensors. Gas-fired boiler diagnostics require combustion analysis and pressure testing that only qualified service personnel should perform. A technician will bring the correct manuals, a flame-rod tester, and a combustion analyzer to pinpoint the fault safely and make sure the boiler meets local codes after repair.
Rough cost: A pro service call runs about $150-400.