NHTSA ID Number: 10205563
Manufacturer Communication Number: 21NA237
Summary
This technical bulletin provides a procedure to perform a cooling system flush to remove possible debris from the cooling system pipes.
20 Affected Products
Vehicles
| MAKE | MODEL | YEAR |
| CADILLAC | ESCALADE | 2021 |
| CADILLAC | ESCALADE ESV | 2021 |
| CHEVROLET | 3500 | 2020-2021 |
| CHEVROLET | SILVERADO 1500 | 2019-2021 |
| CHEVROLET | SILVERADO 2500 | 2020-2021 |
| CHEVROLET | SUBURBAN | 2021 |
| CHEVROLET | TAHOE | 2021 |
| GMC | SIERRA 1500 | 2019-2021 |
| GMC | SIERRA 2500 | 2020-2021 |
| GMC | SIERRA 3500 | 2020-2021 |
| GMC | YUKON | 2021 |
| GMC | YUKON XL | 2021 |
Condition
Some customers may comment on lower heater performance from the driver side HVAC vents when compared to the passenger side.
• In some cases, the driver side center dash vent will have the lowest temperature.
Cause
This may be caused by a blocked heater core tube.
Correction
Flush the cooling system using a flushing agent recommended by GM.
Note: GM of Canada is working on making this product available from other sources but as of the time of publication, the source in Canada will be Canadian Tire under part number 038–0891.
⇒ Perform a flushing procedure using Blue Devil Radiator Flush Cooling System Cleaner, which is approved by GM engineering.
Service Procedure
Important: All signs of the cooling system cleaner must be flushed completely from the cooling system before adding the coolant.
Refer to Cooling System Draining and Filling and Flushing in SI.
Note: The temperature difference between the vents when the process is complete should no more than 5-7 degrees C with the engine at full operating temperature with all vents open. If the temperature difference persists after flushing, the dealer should contact TAC.
1. Drain coolant and wash all of the coolant out of the system with clean drinkable water.
2. Add flushing chemical (one container) to the surge tank and fill the cooling system with clean drinkable water.
Note: Do not allow the vehicle to become exposed to sub-freezing temperatures with the engine off, the flushing chemical provides no freeze protection.
3. Allow the engine to idle for 4 hours, the vehicle can also be driven if desired during this period.
4. Confirm that the heater outlet temperatures are within 5-7 degrees C with all vents open and the heater on high fan with outside air.
5. Drain and wash the cooling system with clean drinkable water and refill with a 50/50 mix of Dexcool Coolant and clean drinkable water.
The performance of the heater may improve very soon after the flushing chemical is placed in the system. The chemical must remain in the system for between 3 and 4 hours to have the effect of removing the deposit that is causing the heater core to be blocked. This material is primarily in the radiator, so if it is not thoroughly cleaned out, the condition could recur.
1 Associated Document
Manufacturer Communications
Bulletin No.: 21-NA-237
Date: November, 2021
https://www.nhtsa.gov/recalls?nhtsaId=10205563
- Specially formulated for long service intervals, the coolant can last up to 5 years or 150,000 miles. (Maintenance needs vary with different uses and driving conditions. See your Owner's Manual for more information)
- Provides effective long-term anti-corrosion support by protecting brass, cast iron, steel, solder, and copper components. Also provides superior high-temperature protection for aluminum components.
- Non-silicate formula retains excellent heat transfer characteristics for improved water pump life
- Long shelf life: storage-stable for 8 years
- The backwards compatible formula can be used with conventional cooling systems and may also be used for service of all 1994-95 GM vehicles EXCEPT 1994 Cavaliers/Sunfires with 4-cylinder engines. Must be replaced every 2 years/30,000 miles whenever used in a vehicle not originally designed to use Dex-Cool
- ZEREX DEX-COOL antifreeze coolant is approved by General Motors to the GM 6277M specification
- ZEREX DEX-COOL antifreeze coolant contains no phosphates, silicates, borates, nitrates, amines and nitrites
- Valvoline ZEREX DEX-COOL antifreeze coolant is a patented* carboxylate formulation with a service life of up to five years or 150,000 miles
- When diluted 50% with water, ZEREX DEX-COOL protects modern engine components from winter freezing and summer boiling
- For any product use or product technical questions call 1-800-TEAM-VAL
- ACDelco 10-101 DEX COOL (ORANGE)
- Contains A Bittering Agent
- OEM
- Contains a bittering agent
- ZEREX DEX-COOL antifreeze coolant is approved to the GM 6277M specification
- ZEREX DEX-COOL antifreeze coolant contains no phosphates, silicates, borates, nitrates, amines and nitrites
- Valvoline ZEREX DEX-COOL antifreeze coolant is a patented* carboxylate formulation with a service life of up to five years or 150,000 miles
- When diluted 50% with water, ZEREX DEX-COOL protects modern engine components from winter freezing and summer boiling
- For any product use or product technical questions call 1-800-TEAM-VAL
- Designed to quickly pinpoint leaks in cooling systems that use DEX-COOL (orange) coolants
- Special formula will not change the color of the coolant
- Fluorescent dye assists with visual leak detection to eliminate guess work
- Works in conjunction with the ACDelco Ultra Violet (UV) Leak Detection Lamp Kit
- Backward compatible with previous Dexron automatic transmission fluids and can be used as a much-improved replacement for older vehicles/transmissions originally using previous Dexron fluids
- Improved performance over previous Dexron fluids in: friction durability, viscosity stability, aeration and foam control, and oxidation resistance
- Potential to enable improved fuel economy and longer transmission life
- Provides for extended drain intervals. Provides consistent shift performance, even in extreme conditions.
Last update on 2022-07-03 / Affiliate links / Images from Amazon Product Advertising API
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