A 2002 Chevrolet Blazer is specified with a 195°F (91°C) thermostat. That number is the thermostat’s rated opening temperature from the factory specifications, which is the figure to match when you buy a replacement.
The specified thermostat rating
The 2002 Chevrolet Blazer owner manual, in its “Capacities and Specifications” section, lists the thermostat as “Thermostat Specification ……195°F (91°C)”. The same specifications table identifies the engine as a Vortec 4300 V6, so the rating applies to that powertrain.
What the 195°F rating does and does not tell you
A thermostat rating is the temperature at which the valve begins to open and let coolant flow to the radiator. It is not a fixed reading of how hot the engine runs. Coolant temperature varies with load, outside air temperature, airflow through the radiator, and the cooling system’s overall condition. If a Blazer runs hotter or cooler than you expect, the thermostat rating alone cannot explain why. Diagnosing overheating requires checking the coolant level, radiator cap, cooling fan operation, and the temperature gauge or scan-tool reading under real conditions.
Thermostat part number for reference
The owner manual’s “Normal Maintenance Replacement Parts” section lists thermostat part number 12559051. The manual also warns that listed replacement numbers can change. If the number printed on the part you are replacing does not match, or you have questions about fitment, contact a GM dealer parts department before ordering.
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- 【Compatible With Chevy】Engine Thermostat Compatible With 1996-2005 Astro V6 4.3L | 1996-2005 Blazer V6 4.3L | 1996-1998 C1500 V6 4.3L | 1996-1999 C1500B V8 5.0L,5.7L | 1996-1999 C1500 Suburban V8 5.7L | 1996-1998 C2500 V8 5.0L |1996-2000 C2500 V8 5.7L | 1996-1999 C2500 Suburban V8 5.7L | 1996-2000 C3500 V8 5.7L | 2000 C3500HD V8 5.7L | 1996-2002, 2004-2014 Express 1500 V6 4.3L | 1996-2002 Express 1500 V8 5.0L,5.7L | 1996-2002 Express 2500 V8 5.0L | 1998-2002 Express 2500 V8 5.7L
- 【Compatible With Chevy】Engine Thermostat Compatible With 1998-2005 Express 2500 V6 4.3L | 1996-2002 Express 3500 V8 5.7L | 1996-1998 K1500 V6 4.3L | 1996-1999 K1500 V8 5.0L,5.7L | 1996-1999 K1500 Suburban V8 5.7L | 1996 K2500 V8 5.0L | 1996-2000 K2500 V8 5.7L | 1996-1999 K2500 Suburban V8 5.7L | 1996-2000 K3500 V8 5.7L | 1996-1999 P30 V6 4.3L | 1996-2004 S10 V6 4.3L | 1999-2002,2007-2013 Silverado 1500 V6 4.3L |2007 Silverado 1500 Classic V6 4.3L | 1996-2000 Tahoe V8 5.7L
- 【Compatible With GMC】Engine Thermostat Compatible With GMC 1996-1998 C1500 V6 4.3L | 1996-1999 C1500 V8 5.0L,5.7L | 1996-1999 C1500 Suburban V8 5.7L | 1996-1998 C2500 V8 5.0L | 1996-2000 C2500 V8 5.7L | 1996-1999 C2500 Suburban V8 5.7L | 1996-2000 C3500 V8 5.7L | 1999-2000 C3500HD V8 5.7L | 1996-2002,2004-2005 Jimmy V6 4.3L | 1996-1998 K1500 V6 4.3L | 1996-1999 K1500 V8 5.0L,5.7L | 1996-1999 K1500 Suburban V8 5.7L | 1996-2000 K2500 V8 5.7L | 1996-1999 K2500 Suburban V8 5.7L | 1996-2000 K3500 V8 5.7L
- 【Compatible With GMC】Engine Thermostat Compatible With GMC 1996-1999 P3500 V6 4.3L | 1996-1999 P3500 V8 5.7L | 1996-2005 Safari V6 4.3L | 1996-2014 Savana 1500 V6 4.3L | 1996-2002 Savana 1500 V8 5.0L,5.7L | 1996-2002 Savana 2500 V8 5.0L,5.7L 1998-2005 Savana 2500 V6 4.3L | 1996-2002 Savana 3500 V8 5.7L | 2000-2002 Savana 3500 V6 4.3L | 1999-2013 Sierra 1500 V6 4.3L | 2007 Sierra 1500 Classic V6 4.3L | 1996-2004 Sonoma V6 4.3L | 1996-2000 Yukon V8 5.7L
- 【Compatible With Oldsmobile & Cadillac】Engine Thermostat Compatible With 1996-2001Oldsmobile Bravada V6 4.3L | 1999-2000 Cadillac Escalade V8 5.7L
Buying a replacement correctly
Aftermarket catalogs for the 2002 Blazer show more than one thermostat opening temperature under the same vehicle category, so a search result is not automatically the correct part. AutoZone’s catalog page for 2002 Blazer thermostat and housing parts is one example of a listing that presents different opening temperatures. Retail listings change over time, so confirm each one against your vehicle before you buy.
Before ordering, work through these checks:
- Confirm the listed opening temperature is 195°F (91°C), matching the factory specification.
- Confirm the fitment for your exact engine (the 4300 V6 specified in the manual) and your VIN, using a reliable fitment catalog or a GM parts department.
- Compare the part number on the old thermostat or housing with 12559051 and with the catalog listing.
- Check whether the listing includes a new seal or gasket. If it does not, buy one separately and install it with the new thermostat.
- Do not choose a lower-temperature thermostat unless a vehicle-specific, authoritative source calls for it.
Current availability and pricing
Prices, stock levels, and online marketplace availability for thermostats change frequently and were not verified for this article. Check them directly with the seller at the time of purchase.
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Rank #4
- Vehicle Fitment: Fits Chevrolet Blazer 1996-2005 Fits Chevrolet S10 Pickup 1996-2004 Fits Chevrolet Silverado 1500 1999-2013 Fits Chevrolet Silverado 1500 Classic 2007 Fits Gmc Jimmy 1996-2005 Fits Gmc Sierra 1500 1999-2013 Fits Gmc Sierra 1500 Classic 2007 Fits Gmc Sonoma 1996-2004 Fits Isuzu Hombre 1997-1999 Fits Oldsmobile Bravada 1996-2001.
- Interchange Part Number:12557563, 8125575630, 85168, 147-0014, CO34764, 902-107, 6256, 15-1794.
- Complete Installation Ready: Comes complete with a high-durability mounting gasket and precision-machined surface for an airtight seal, eliminating leak points straight out of the box without requiring extra sealing compound.
- Premium Heavy-Duty Metal Construction: Upgraded high-grade aluminum/die-cast metal construction resists extreme thermal expansion, cracking, and coolant leaks far better than standard composite housings, ensuring long-term structural integrity.
- Strict Quality & Bolt-On Fit: Manufactured to stringent OEM dimensional standards for an effortless bolt-on replacement process. Undergoes strict pressure and leak testing to deliver reliable performance under severe driving conditions.
Rank #3
- [Vehicle Fitment]: Compatible with Chevrolet Blazer 2002, Trailblazer 2002-2009, Trailblazer EXT 2002-2006; Compatible with GMC Envoy 2002-2009, Envoy XL 2002-2006, Envoy XUV 2004-2005; Compatible with Oldsmobile Bravada 2002-2004; Compatible with Saab 9-7x 2005-2009; Compatible with Buick Rainier 2004-2007
- [Reference Number]: 902-800, 413192, 85934, 12567750, 12572988, 12602913, 12620112, 24576961
- [Specifications]: ① Thermostat Opening Temperature: 190 Deg. F; ②Outlet Port Quantity: 1; ③ Bolt Hole Center To Bolt Hole Center: 3.13 in; ④ Material: Aluminum; ⑤ Inside Diameter: 1.21 in; ⑥ Mounting Hole Quantity: 2; ⑦ Gasket Or Seal Included: Yes
- [Benefits]: Through strict hardness and crushing tests, having precise structures and reliable performances. More effectively, adjust the heat dissipation capacity to ensure the engine works with in the appropriate temperature range.
- [Buy with Confidence]: A-Premium offers a one-year unlimited-mileage guarantee on our meticulously crafted thermostat housing assembly. We offer a wide variety of automotive accessory categories, ensuring that you can hit the road with peace of mind.
Rank #2
- 【Applicability】The part compatible with Buick Rainier 2004-2007.Compatible with Chevy Trailblazer 2002-2009 Trailblazer EXT 2002-2006.Compatible with GMC Envoy 2002-2009 Envoy XL 2002-2006 Envoy XUV 2004-2005.Compatible with Oldsmobile Bravada 2002-2004.Compatible with Saab 9-7x 2005-2009
- 【Part Number】Replaces 902-800 12620112.pls check the part components number whether match
- 【Advantage】These parts have the same functions as OE parts, please use them with confidence
- 【Note】Please check your part pictures with our pictures, it must be completely same. Or it will not fit your car. It will save your time and cost
- 【Service】 If you have any questions or the items you received with problems, contact us directly
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
