HVACopediaAllied · Furnace troubleshooting
Electrical checks on the furnace
What is going on
A basic electrical checkout on the Allied furnace is quick and catches a lot. You are looking for loose connections, low supply voltage and a blower motor that pulls more current than its nameplate says. Do the wiring check with the power off, then the live readings with the furnace running.
Likely causes
- Loose or burnt wire connection
- Supply voltage outside 120 VAC plus or minus 10%
- Blower motor drawing more amps than its nameplate, from a failing motor or restricted airflow
Check in this order
- Turn off power and check all wiring for loose connections.
- Restore power and run the furnace.
- Check supply voltage at the furnace. Correct voltage is 120 VAC ±10%.
- With the blower access panel in place, check blower motor amp draw with a clamp meter and compare it with the motor nameplate.
- If a reading is off, find the cause before leaving, and call a licensed technician for anything inside the line voltage wiring you are not comfortable with.
Applies to: Furnace electrical checkout
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Source: Allied 92G1UH installation instructions manual, p. 46. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.