# Service bulletin SF631

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service bulletin
- NHTSA id: 10199364
- Published by NHTSA: 2021\-07\-22
- Manufacturer's number: SF631
- Manufacturer's date: 2021\-07\-01
- NHTSA component: ENGINE AND ENGINE COOLING

## NHTSA's summary

Field Service Campaign for Detroit Diesel Engine Fan Activation with A/C. On certain Freightliner and Western Star vehicles with Detroit Diesel engines, the engine fan fails to activate when the A/C pressure switch circuit is opened, resulting in poor A/C cooling performance at idle.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2021/MC-10199364-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2021/MC-10199364-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Engine

## Vehicles listed

- 2022 FREIGHTLINER 108SD
- 2022 FREIGHTLINER 114SD
- 2022 FREIGHTLINER 122SD
- 2022 FREIGHTLINER BUSINESS CLASS M2
- 2022 WESTERN STAR 4700
- 2022 WESTERN STAR 4900
- 2022 WESTERN STAR 5700

## Other bulletins for the same vehicles and component

- [CXA 03\_26\_Surge Tank](/bulletins/11030507.md), 2026-04-02, Other: ENGINE. CX Advocate for discolored coolant surge tanks \(24CSA\-20\)
- [FleetCom\_Heater Core](/bulletins/11027493.md), 2026-01-08, Other: ENGINE. Fleet Communications for Heater Core Plugging
- [TSB54\-377\-FTL](/bulletins/11027199.md), 2026-01-07, Service bulletin: ENGINE. Technical Service Bulletin Low Coolant Sensor
- [CXA\_10\_25\_Conmet Oil Pan](/bulletins/11024958.md), 2025-11-05, Other: ENGINE. CX Advocate for ConMet Oil Pan Insert Additional Issues
- [CXA\_9\_25\_Tech Questions](/bulletins/11023683.md), 2025-10-03, Other: POWER TRAIN; ENGINE. CX Advocate for technical questions/issues raised
- [CXA\_8\_25\_Tech Questions](/bulletins/11022341.md), 2025-09-02, Other: POWER TRAIN; ENGINE; UNKNOWN OR OTHER. CX Advocate for technical questions/issues raised
- [24CSA\-19Rev](/bulletins/11022317.md), 2025-09-02, Other: ENGINE. Revised Customer Service Annoucement for No Trouble Found Heavy Duty Engine Product \(HDEP\) Oil Separator Leaks
- [CXA 4\_25\_DPF Outlet Temp](/bulletins/11017528.md), 2025-05-02, Other: ENGINE. CX Advocate for DPF Outlet Temp High Gen5 DD15 ENGINES
- [CXA 3\_25\_NOx](/bulletins/11016309.md), 2025-04-02, Other: ENGINE. CX Advocate for NOx conversion low faults
- [CXA 3\_25\_DPF Outlet Temp](/bulletins/11016306.md), 2025-04-02, Other: ENGINE. CX Advocate for DPF Outlet Temp High Gen5 DD15 ENGINES

JSON: [/v1/bulletins/10199364](/v1/bulletins/10199364)

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