Jason K Portsmouth , NH November 25, 2020 Appliance: Maytag 30" Built-In Electric Oven Convection JJW9530DDP29 Maytag Oven Jjw9530ddp29: Jenn Air wall oven model jjw9530ddp error code 4d21. How to replace Tangential Fan (Cooling Blower). Internet search for error code 4d21 suggested replacing cooling fan. Replaced cooling fan. 2 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours