Coleman Furnace Error Code 4 FLASH
Limit switch open; a primary or auxiliary limit switch has opened its normally closed contacts, possibly caused by dirty filter, improperly sized duct system, incorrect blower speed setting, incorrect firing rate or faulty blower motor.
SourceColeman Gas Furnace - Service Manual: DGAA077BDTBFurnace Control Diagnostics section
The full 4 FLASH procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
SourceColeman Gas Furnace - Service Manual: DGAA077BDTBFurnace Control Diagnostics section
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Where this code is documented
1 manual in the MyPros+ library documents this code for Coleman furnace.
Models covered by the manuals that document this code
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