Vehicle recall 81V157000 · December 29, 1981
Mack MS200P and MS300P
When the ignition key is in the "on" position and the heater is operating at the "low" or "medium" setting, the heater switch wiring will overload in the event the heater motor…
Source: NHTSA data as of September 22, 2026. Last refreshed Sep 23, 2026, 2:43 AM UTC.
- Summary
- When the ignition key is in the "on" position and the heater is operating at the "low" or "medium" setting, the heater switch wiring will overload in the event the heater motor seizes.
- Remedy
- A speed variation resistance unit and an electric motor moisture protection cap will be installed without charge.
- Notes
- Vehicle description: trucks.system: heating; cab heater motor, electrical switch.consequences of defect: if the vehicle is standing still (parked or stopped intraffic) heat generated by the overload may melt and ignite the surroundingplastic housing and wire covering. A fire could spread quickly throughout thecab, causing serious injury to vehicle occupants.note: owner is advised to make sure heater/defroster fan motor is functionalbefore using cab heater prior to repair. Heater/defroster blower should not beused in "low" or "medium" speeds while the vehicle is stopped or engine isidling.
Recall details
- NHTSA campaign
- 81V157000
- Reported to NHTSA
- December 29, 1981
- Filed by
- MACK TRUCKS, INCORPORATED
- Owner notification
- August 12, 1982
- Vehicles potentially affected
- 4,920
- Initiated by
- the manufacturer
- Components
- Visibility › Defroster/defogger/HVAC system › Fan/motor
Vehicles covered
As listed by NHTSA. A recall usually covers only some vehicles of each model and year, often a production date range.
- Mack MS200P (1979-1981): 1981, 1980, 1979
- Mack MS300P (1979-1981): 1981, 1980, 1979
Has your Mack been repaired?
Recalls here come from NHTSA’s records for the model and year. Not every vehicle of a model is included in every recall, and this site can’t see whether a repair has been done. Only a VIN lookup can tell you that.
NHTSA’s VIN search doesn’t show recalls that were already repaired, recalls more than 15 years old, or some small manufacturers’ recalls. A Mack dealer can also check your VIN. Recall repairs are free.