Furnace short-cycles on high-limit

Furnace / gas

AirCompDX - Field Reference for Air Compressor Techs
All HVAC symptoms
1

Restricted airflow

med
CheckFilter, blower wheel, closed dampers, undersized returns.
FixCorrect static; target <0.5" WC total ESP on residential.
2

Oversized furnace

low
CheckManual J vs input BTU.
FixDownsize on replacement, or add stages if 2-stage available.
3

Failed limit switch

med
CheckOpen cold; won't reset.
FixReplace with exact-part limit.
Safety

Pull the disconnect and lock out before opening HVAC equipment. Discharge dual-run capacitors before handling. Refrigerant recovery and brazing require EPA 608 certification and proper PPE.