Furnace pilot is on, pilot ignitor continues to click, no main flame
I have a Carrier Weathermaker SX model 58SX060-CC-1, series 150, 66,000 BTU furnace. The intake/exhaust fan starts when the thermostat tells it to, the pilot lights, but the main flame does not ignite. The pilot ignitor continues to click like it does not notice the pilot is lit (I think). The thermostat is connected also to an A/C system, all of which works fine (main house air circulation is good).
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I believe this is the furnace with a spark to light the pilot light. If so the best advice I can give is to replace the whole pilot assembly. There is a very old style flame sensor in there that is not serviceable. This has driven many a technician around the bend.
**NOTE: It is a real pain to get out, and back in. You need to take off the fire box cover and the panel underneath it to get it out. You also need to take the pilot tube off the gas valve. This may be something that you want to call a service tech for. It could be a little tricky and because you are dealing with gas, you want to make sure that it is put together correctly and safely.
Hi, You say that it will light and then shut-off when the ELECTRIC pilot shuts off? If it has an automatic pilot ignition, it wouldn't have a thermocouple? It would have an ignition module with a flame sensor. Could you check this for me and let me know which one you have for sure? I can help you out better if I knew. Thank you and please get back to me. Sincerely, Shastalaker7 Ps If it is electronic, there will be a flame sensor mounted next to the pilot. It has a ceramic body with a metal rod coming from the end.You can take a piece of steel wool not sand paper and clean the metal rod (sensor). The pilot flame will surround this keeping the burners on.After cleaning it, and if the pilot continues to go out, I would say that you're ignition module has an intermittent internal problem, and needs to be changed.
There is a small tube that comes off the inducer for cracks or water. If there are cracks then the pressure switch that it is attached to may not be closing all of the time. Also sometimes you can get water in that tubing which will also cause the pressure switch to not close. If thats the case shorten the tube so there is no low droop in it where water can collect. Another thing that I would do is disconnect the tube at the indicer, take a straightened out paper clip or stiff wire and poke it in the nipple on the inducer to make sure it is clear too. Let me know if any of these work. There may be other things we can do.
The carrier sx series went through a number of control systems over the years. can you find the full model, and series numbers? They are located behind the door on the left side. (i.e. 58 sxc080-100 series100)
Remove all power from the furnace, it is likely the brain in the furnace is need of being reset, from the battery replacement, why did you change the battery, was there an indicator telling you to change it?
Many times just removing all the power to the furnace will do the trick with a reset, if not let me know and we will go from there, but it sounds like the main brain is confused or bad, more likely confused, so try the power removed first.
There are 4 -steps for full run time to kick in a furnace.. step-1, inducer fan runs & prove thru the air tube which closes a switch and tell the circuit board to go to step-2, the igniter lights the pilot & prove its lit by heating the thermocouple, which tells the circuit board to go to step-3, opens the gas valve to dump gas in, which will light from the pilot light, and prove by a flame sensor metal stick on the last burner , which heats up and tell the circuit board Saying, ok , I've got flame.. step-4. when the box heats up, it closes a switch and turn on the main fan...! (Some gas-valves has a brain -or circuit board on top of them and are real sensetive to moisture..)
I have serviced these furnaces for 20 years and I can tell you most of these models did not have diagnostic lite on them. (although some did, especially if the control board has been replaced) The problem is most likely a bad 3 wire pilot. This will cause exactly what you describe. 2 things to consider though. 1, If you were to replace the pilot don't get a cheaper knockoff. In my experience these do not last long at all. Get the right one from a carrier dealer. It will cost more but be much more reliable. 2 What is the condition of the secondary heat exchanger? Most if not all of the sx series had issues with the secondary heat exchangers rotting out and leaking. If the furnace is out of warranty you would be much better replacing the furnace as the cost of replacing the secondary heat exchanger will probably be almost the same as a new furnace. ( those babies are EXPENSIVE!)