I have a Carrier 58DX-100-DC furnace that I have a problem with, The inducer motor will come on and run then the pilot will light and then the burner comes on and a couple minutes or less the blower comes on it will stay like this for about 2 or 3 minutes then the inducer motor stops and the gas shuts off and it goes through the above cycle again, I've changed the motor blower control board and the pressure switch and made sure all the hoses are clear still no go, any help would be appreciated!

I will take a wild guess on this one. Did you clean or replace the flame sensor if you have one? I have seen them do strange things before. Also a glow bar/Hot surface ignition device can also make this happen but it is rare.

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Originally Posted by hvac1000

I will take a wild guess on this one. Did you clean or replace the flame sensor if you have one? I have seen them do strange things before. Also a glow bar/Hot surface ignition device can also make this happen but it is rare.

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No flame sensor, No glow bar either, has spark igniter! This system has an inducer control board that has a relay and 4 diodes on it is it possible that is the culprit?

Check to see if this has a 2 or 3 wire pilot assembly because those have been known to cause trouble. Wires exit the bottom.

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Originally Posted by hvac1000

Check to see if this has a 2 or 3 wire pilot assembly because those have been known to cause trouble. Wires exit the bottom.

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It has a 3 wire!

From what I have read in your previous posts you have already spent some$$.

These pilots assemblies do go bad. They have a bimetal that over time looses its ability to operate the switch assembly in turn causing erratic operation.

Make sure that the pilot is setup for natural gas or LP depending upon what you have and if reusing your old orifice make sure the little hole that the pilot gas passes through is clean BUT do not drill it out use a very thin wire to clean.

This will also make sure the pilot lite reaches its maximum height to activate the switch in the pilot assembly.

Will do, I'm at work right now but will check when I get home Thanks a lot for your help I really do appreciate it. I'll let you know what I find.

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Originally Posted by hvac1000

From what I have read in your previous posts you have already spent some$$.

These pilots assemblies do go bad. They have a bimetal that over time looses its ability to operate the switch assembly in turn causing erratic operation.

Make sure that the pilot is setup for natural gas or LP depending upon what you have and if reusing your old orifice make sure the little hole that the pilot gas passes thru is clean BUT do not drill it out use a very thin wire to clean.

This will also make sure the pilot lite reaches its maximum height to activate the switch in the pilot assembly.

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That did the trick I replaced it and found an erratic blower safety switch which I had jumped out when I first started troubleshooting it so it was 2 problems, The new 3 wire pilot assembly was not working properly when I first put it in, had to make an adjustment with the bimetal switch, was working fine for pilot but not calling for gas but finally got it working We're warm again Thanks a lot for your info I really appreciate it!

Oh by the way I was able to take back the blower motor board and get my money back!

Good deal glad you got it fixed.