Heat pump blowing cold air in heat mode

Heating / heat pump

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

Reversing valve stuck or solenoid failed

high
CheckEnergize O (or B) call. Listen/feel valve shift. Measure 24 V at solenoid.
FixReplace solenoid coil first ($$). Replace reversing valve if body stuck (braze-in).
ToolsMultimeter · Brazing kit · Nitrogen purge
SafetyRecover refrigerant before brazing. Nitrogen purge during braze.
2

Defrost stuck / iced outdoor coil

med
CheckOutdoor coil packed with frost/ice for >30 min.
FixForce defrost (test pins on board). Replace defrost board or sensor if it doesn't cycle.
3

Aux/emergency heat not engaging

med
CheckOn W call, measure for heat strip current draw. Check sequencers / element continuity.
FixReplace failed sequencer or open element. Verify breaker not tripped on heat-strip subpanel.
ToolsClamp meter · Multimeter
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.