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Thermal Zone
Furnace

Model # GD120K20B Official Thermal Zone gas furnace

Here are the diagrams and repair parts for Official Thermal Zone GD120K20B 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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ALL PARTS
Showing 10 of 31 parts  |
Capacitor 621435
#23

80+ downflow furnace diagram

Capacitor

Part #621435

Replaced by #12908

?
Manufacturer substitution
This part replaces 621435. Substitute parts can look different from the original.
This item is not returnable
$5.26 | 
16% OFF Phone Price : $6.26
In Stock
Furnace Electronic Control Board 903106
#27

80+ downflow furnace diagram

Furnace electronic control board

Part #903106

$297.66
In Stock
Furnace Blower Fan Motor Assembly 902816
#25

80+ downflow furnace diagram

Furnace blower fan motor assembly

Part #902816

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

Switch 632212
#19

80+ downflow furnace diagram

Switch

Part #632212

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

Sensor Rod 632316
#6

80+ downflow furnace diagram

Sensor rod

Part #632316

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

Transformer 621486
#26

80+ downflow furnace diagram

Transformer

Part #621486

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

Switch 626435
#20

80+ downflow furnace diagram

Switch

Part #626435

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

Gas Valve 624586
#2

80+ downflow furnace diagram

Gas valve

Part #624586

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

Main Burner Ofrifice (43 Drill) (not Shown) 661043
#3

80+ downflow furnace diagram

Main burner ofrifice (43 drill) (not shown)

Part #661043

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

Furnace Burner 660812
#1

80+ downflow furnace diagram

Furnace burner

Part #660812

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

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Time required
 15 minutes or less
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Repair difficulty
Time required
 45 minutes or less
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Repair difficulty
Time required
 45 minutes or less

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