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B1004 — Blower Motor Circuit Open
SeriousHVACPower derate likely — plan to stop soon
Seen on: Heavy Truck
Blower Motor Circuit Open. Common causes: Blower motor circuit open.
Don't risk it — get a diesel tech on the truck.
Look up listed providers near you and give them this code when you call.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Blower motor circuit open
- Failed blower motor
- broken wiring
- blown fuse
First moves (roadside)
- Check HVAC fuse
- test blower motor resistance
- check motor power and ground
FAQ
What does B1004 mean?
Blower Motor Circuit Open. Common causes: Blower motor circuit open.
How serious is B1004?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of B1004?
The most common cause is: Blower motor circuit open. Other possibilities include Failed blower motor; broken wiring; blown fuse.
Can I keep driving with B1004?
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
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General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.