Thermal Zone
Furnace

Model # GM120K16B Official Thermal Zone gas furnace

Here are the diagrams and repair parts for Official Thermal Zone GM120K16B gas furnace, as well as links to manuals and error code tables, if available.

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Model diagram and schematic

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Showing 10 of 32 parts  |

Capacitor 621435
#22

80+ upflow furnace diagram

Capacitor

Part #621435

Replaced by #12908

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Manufacturer substitution
This part replaces 621435. Substitute parts can look different from the original.
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Furnace Control Module Assembly 903108
#25A

80+ upflow furnace diagram

Furnace control module assembly

Part #903108

The manufacturer no longer makes this part, and there's no substitute part

Furnace Electronic Control Board 903106
#25

80+ upflow furnace diagram

Furnace electronic control board

Part #903106

The manufacturer no longer makes this part, and there's no substitute part

Switch 626464
#29

80+ upflow furnace diagram

Switch

Part #626464

The manufacturer no longer makes this part, and there's no substitute part

Furnace Blower Assembly 902815
#23

80+ upflow furnace diagram

Furnace blower assembly

Part #902815

The manufacturer no longer makes this part, and there's no substitute part

Furnace Temperature Limit Switch 626425
#18

80+ upflow furnace diagram

Furnace temperature limit switch

Part #626425

The manufacturer no longer makes this part, and there's no substitute part

Switch 632212
#17

80+ upflow furnace diagram

Switch

Part #632212

The manufacturer no longer makes this part, and there's no substitute part

Transformer 621486
#24

80+ upflow furnace diagram

Transformer

Part #621486

The manufacturer no longer makes this part, and there's no substitute part

Furnace Burner Flame Roll-out Switch 626343
#7

80+ upflow furnace diagram

Furnace burner flame roll-out switch

Part #626343

The manufacturer no longer makes this part, and there's no substitute part

Gas Valve 624586
#2

80+ upflow furnace diagram

Gas valve

Part #624586

The manufacturer no longer makes this part, and there's no substitute part

Symptoms for gas snowblowers

Choose a symptom to see related snowblower repairs.

Main causes: broken shear pins, worn or loose auger drive belt, auger drive cable failure, damaged auger, bad gear case…

Main causes: clogged chute, snow build-up in auger housing, broken auger shear pins, auger drive belt needs adjustment, …

Main causes: stale gas, clogged carburetor, clogged or broken fuel line, dirty spark plug, bad rewind starter, incorrect…

Main causes: punctured tire, damaged rim…

Main causes: clogged chute, damaged auger blades, broken shear pins, worn auger belt, damaged gear case, engine problems…

Things to do: replace the spark plug, change the oil, rebuild the carburetor, adjust valve lash, adjust or replace the b…

Main causes: dirty carburetor, clogged fuel filter, dirty spark plug, incorrect valve lash, leaky engine gaskets…

Main causes: dirty carburetor, stale fuel…

Main causes: loose drive clutch cable, damaged drive clutch cable, worn friction disc, scraper blade scraping the ground…

Repair guides for gas snowblowers

These step-by-step repair guides will help you safely fix what’s broken on your snowblower.

How to replace a snowblower fuel filter

How to replace a snowblower fuel filter

Replace the fuel filter on your snowblower if it's clogged or damaged.…

Repair difficulty
Time required
 15 minutes or less
How to adjust snowblower skid shoes

How to adjust snowblower skid shoes

To prevent snowblower auger and shave plate damage, adjust the skid shoes regularly to keep the shave plate ¼-inch high.…

Repair difficulty
Time required
 15 minutes or less
How to rebuild a snowblower carburetor

How to rebuild a snowblower carburetor

Rebuild the carburetor on your snowblower if the engine isn't getting fuel.…

Repair difficulty
Time required
 45 minutes or less

Effective articles & videos to help repair your furnaces

Use the advice and tips in these articles and videos to get the most out of your snowblower.

How to get your furnace ready for winter

How to get your furnace ready for winter

Get expert tips for preparing your furnace for winter. Follow maintenance tips to keep your furnace in top shape.…

Introducing new technical repair content that we’re developing for the Sears Technical Institute

Introducing new technical repair content that we’re developing for the Sears Technical Institute

Learn about Sears Technical Institute and the advanced technical content being developed for aspiring appliance techs.…

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Top questions about Sears and Sears PartsDirect

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