Furnace Ignition Problem

Old 10-21-02, 09:19 AM
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gas furnance wont light

I have a Kenmore gas furnace. The blower works fine, but for some reason the electrical ignition will not light. There is a constant clicking sound, but the fire will not start. I tried to manually light the gas, but it seems there also is not gas flow. If you need more info please ask, its getting cold and I would love for a reply.

Old 10-21-02, 11:13 AM
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Hello msclbndfrk. Welcome to My Gas Appliances forum and the Do-It-Yourself Web Site.

Electronically operated and controlled appliances often require several tests on several componets to determine the exact cause of a problem.

The procedures and methods vary and at times can become rather complexing. Therefore, be advised that only your heating contractor may be able to resolve the problem.

Below are a few of the potiental and or possible causes for the problem description you provided:

If the pilot lighting system has an electronic sparker that lites the pilot flame, and there is no sparking, the sparking element and or electronic module are the most likely defective parts. I would suggest you clean the sparker and pilot assembly first and retest.

Also check for a good electrical connection, etc. to the sparking device, spark module and the pilot flame sensor, if the pilot flame appears and is heating the sensor element.

The wire that should be cleaned is usually green in color and attached to the sparker module. The other end of this wire will be attached to the furnaces frame.

Be sure the terminal connection is clean and free of any rust and or corrosion. Wire brush or use sanding paper to clean the effected area, then reattach the terminal end exactly as you found it prior to removal.

The pilot flame sensor is not the same as a thermocouple. It's a true flame sensor that sends a signal the main electronic sparking module that a pilot flame is established. The pilots flame will be heating this element directly.

Once the signal is received at the main spark module, the main module allows the gas valve to open, sending gas to the burners. If the signal is not sent or recieved, the module will not allow the burners gas valve to open. Therefore, either no burner flames or the burner flames will cycle on and off intermittently.

Below is a list of some of the possible problems and solutions for heating appliances using a Glow Bar type ignition system. Pick and choose which type, problem or condition applies to the heating appliance you have.

Defective Glow Coil:
The glow coil may glow but just be too weak to allow current to continue to flow to the magneto coil and other parts it supplies current to. Replacing the Glow Bar {Hot Surface Ignitor} may solve the problem.

The main computer circuit board also controls and regulates functions of the heater. It too may have a defective componet.

Defective Solenoids:
The solenoids are on top or inside the body of the gas valve body. Solenoids also supply voltage to a glow bar {if applicable} gas to the pilot flame {if applicable} main burner gas and or other parts and componets of the entire electrical loop.

Defective Gas Valve:
Remove entire unit as an assembly. Take the entire assembly to your local appliance parts store for testing. Gas valves are not repairable. Replacement is the only option, if defective.

Do Not attempt to repair the gas valve!
This is a NON repairable item!

The ideal method for determining if either the solenoid, gas valve, gas valve parts, electronic parts or componets, circuit boards or other componets are defective, is to remove the item or items.

Take the entire assembly and or componets to the local retail appliance parts store or heating appliance dealers retail store and have the entire assembly and or parts inspected and or tested, as needed.

Flame Sensor:
This part is located on the burner or near the pilot assembly. If it's defective, it will cause the glow coil to not function or cause the problem your describing.

The flames sensor element, is the part which the pilot flame heats once a pilot flame is established. Cleaning the flame sensor element using fine grit sand paper or steel wool may solve the problem.

Not all furnaces have a seperate flame sensor element. If your heating is equipped with one, insure the flame sensors element is connected securely and correctly in the pilot assembly, is being heated by the pilots flame, is properly connected to the computers modual or spark modual and that either or both modual is in turn grounded well and correctly.

The only positive proof any part is functioning correctly, is to carefully remove the part or parts you suspect to be the potential culprit, and have the local appliance parts store person test it or check it. Appliance parts dealers carry replacement parts for all appliances and are listed in the phone book under appliances.

Read the manufacturers online web site for product information, problem solving methods, disassembly, reassembly methods, repair proceedures and instructions, pictorials and schematics, which may be available online.

Be absolutely positive the electrical power is turned OFF before attemping ANY repairs!

Read the RECENT postings within this forum, pertaining to heaters and the replies offered. Doing so will provide you with additional information.

Regards & Good Luck
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Tom_Bart...Fast, Fair, Friendly & Highly Efficient.....
Energy Conservation Consultant & Natural Gas Appliance Problem Diagnostics Technician.
Old 10-21-02, 02:51 PM
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much thanks

thank you very much for the info, I cleaned out the area of the igniter and everything works just fine, once again it seems a simple task can take care of a possibly expensive problem. I greatly appreciate your advice and hope this website prospers.

super greatful
Old 11-03-02, 02:42 PM
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similar problem

I have a Bryant gas furnace that I am just turning on for the season. It worked fine last year and I took time to vacuum out accumlated dust and clean the filters, so I may have accidentally caused this problem:

The electronic pilot light comes on just fine at power up. Then after about 30 seconds, probably when it would want to fire up the burners, the light goes out. The unit starts sparking, the pilot light comes up again, then goes off. This cycle repeats and the burners themselves never light.

I don't see the green pilot light sensor wire mentioned above.

Thanks for any ideas.

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