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Old 01-06-2013, 10:48 AM   #16
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Furnace clicking noise, blower runs continuously


Wow. Looks like the original gas valve and milivolt pilot burner. Based on the age i would definitely replace the fan and limit controls. If the wiring is cracked or brittle, which is common on older furnaces, replace all the 110 volt wiring. If it was my furnace, I would be tempted to also change the milivolt valve and pilot to a 24 vac valve which also means installing a transformer, thermocouple and new thermostat. Id even consider going with spark ignition. However, if your paying retail for all your parts and not comfortable doing the work yourself then it would probably more expensive than its worth. Plus with the age of the furnace, the chances of the heat exchanger cracking in the near future is also a possibility.

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Old 01-06-2013, 12:40 PM   #17
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Furnace clicking noise, blower runs continuously


Can't say for sure. it may be working fine. Replace the limit and see how the blower works after doing that.
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Old 01-06-2013, 06:52 PM   #18
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Furnace clicking noise, blower runs continuously


Thanks for the replies. Good points, the burner fires up fine and the pilot is good still so I don't think those are the issues. It seems like a switch issue in my case here. The furnace is, I'm sure an original from when the house was built, if not, its pretty old but in good working condition. Probably better to just replace the whole unit in the near future.

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Old 01-06-2013, 08:53 PM   #19
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Furnace clicking noise, blower runs continuously


OK first things first.
Attach a ground wire on the green screw of that new motor and attach the other end to the frame of the furnace. People can die from the lack of that ground.
That furnace is 45yrs + in age so I am suprised everyone here isn't saying..change it.
Your furnace fan is controled by an adjustable fan control. If the fan is coming on (within 5 minutes of the gas coming on) and is continuing to blow after the thermostat is satisfyed until the air coming out the register is starting to cool, this is the way it was designed to work.
The gas should be coming on whenever the thermostat is calling for heat.

If you wish to identify where the clicking sound is coming from..Take your longest screwdriver and put the handle against your ear and the metal end against the part you want to test. (stethescope). Obviously don't touch anything that could shock you.
I'd start with the gas valve!

Last edited by how; 01-06-2013 at 09:20 PM.
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Old 01-06-2013, 09:16 PM   #20
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Furnace clicking noise, blower runs continuously


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OK first things first.
Attach a ground wire on the green screw of that new motor and attach the other end to the frame of the furnace. People can die from the lack of that ground.
That furnace is 45yrs + in age so I am suprised everyone here isn't saying..change it.
Your furnace fan is controled by an adjustable fan control. If the fan is coming on (within 5 minutes of the gas coming on) and is continuing to blow after the thermostat is satisfyed until the air coming out the register is starting to cool, this is the way it was designed to work.
The gas should be coming on whenever the thermostat is calling for heat.

If you wish to identify where the clicking sound is coming from..Take your longest screwdriver and put the handle against your ear and the metal end against the part you want to test. (stethescope).
I'd start with the gas valve!
The ground is attached to the new motor already. You can see from the picture. Its the green/yellow wire attached to green screw on the outside of the motor and I attached the other end to the black cover plate. Initially the other end of the ground was attached to the motor bracket that came with the motor but the bracket doesn't fit the original set up on the furnace so I took off the bracket and attached the ground to the cover plate. It's still touching metal to metal and the motor is attached to the bracket on the furnace which is all metal. Is that ok? Or should I drill a small hole to attach the ground to the bracket on the furnace?

I understand what you're saying about the way the furnace is suppose to operate but the the fan continues to blow continuous. It should shut off after the furnace cools which it doesn't. All the while i'll hear clicking then the burners light while the blower is still blowing and then the clicking again as the burners shut off. Today, however, its been running normal so far after 2 cycles. I suspect an intermittent problem which leaves me to believe that the limit and or fan control is starting to go.
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Old 01-06-2013, 09:35 PM   #21
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Furnace clicking noise, blower runs continuously


The motor is still electrically isolated by the rubber ends. The ground needs to bridge them to work. Wire is cheap and easily spiral wraps around the motor wire back to any securing point that is bare metal.

If the fan is running on too long then the lever on the fan control should be adjusted to a higher temp. Turn off the power and move that lever 1/8"inch to the right to a higher temp. It should have temp listings on the control. If that doesn't do it, move it another 1/8 ". Move it too high and the furnace may start limiting out before the fan starts. It's an old part and may no longer be adjustable but it is the way to try to have the fan shut off when you want.

Last edited by how; 01-06-2013 at 09:50 PM.
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Old 01-06-2013, 09:51 PM   #22
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Furnace clicking noise, blower runs continuously


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The motor is still electrically isolated by the rubber ends. The ground needs to bridge them to work.

If the fan is running on too long then the lever on the fan control should be adjusted to a higher temp. Turn off the power and move that lever 1/8"inch to the right to a higher temp. It should have temp listings on the control. If that doesn't do it, move it another 1/8 ". Move it too high and the furnace may start limiting out before the fan starts. It's an old part and may no longer be adjustable but it is the way to try to have the fan shut off when you want.
I will drill a hole in the furnace bracket and attach the other end to it.

I still think there's something wrong because of the clicking and it's not cycling normal. Regarding the lever, I have adjusted the lever. I lowered it to around 100. It was originally around 110 and was still not functioning right. I will try again.
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Old 01-06-2013, 10:13 PM   #23
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Furnace clicking noise, blower runs continuously


Try re reading my post again. I'm not sure how you got the idea to lower the temp unless you are pulling my chain.
You want that lever going to the right to a higher temp.
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Old 01-06-2013, 11:13 PM   #24
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Furnace clicking noise, blower runs continuously


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Try re reading my post again. I'm not sure how you got the idea to lower the temp unless you are pulling my chain.
You want that lever going to the right to a higher temp.
Sorry for the misunderstanding, what I was referring to is the fan off temp lever which I turned the lever to the left to lower the temp at which the fan would shut off. It was originally at around 110 and now its at around 90 (see pic). I think the lever should be around 95-100 from what I've read elsewhere.
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Old 01-07-2013, 12:04 AM   #25
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Furnace clicking noise, blower runs continuously


I'd suggest turning the temp control to the right. Higher! If it was at 110F..turn it to 115F. If that doesn't do it with the next heating cycle... try 120F.
You are adjusting the fan to turn off at a higher heat exchanger temp.
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Old 01-07-2013, 12:23 AM   #26
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Furnace clicking noise, blower runs continuously


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I'd suggest turning the temp control to the right. Higher! If it was at 110F..turn it to 115F. If that doesn't do it with the next heating cycle... try 120F.
You are adjusting the fan to turn off at a higher heat exchanger temp.
OK, I will try that. Could you explain why the fan is suppose to turn off at a higher temp? Shouldn't it be blowing till the furnace cools down and then shut off?
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Old 01-07-2013, 12:56 AM   #27
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Furnace clicking noise, blower runs continuously


The Heat exchanger goes from hot to luke warm when cooling down. When a fan control gets out of calibration over time it starts turning off the fan at lower and lower heat exchanger temps. Eventually the heat exchanger never gets cool enough to turn off the fan control so it runs continuously.
We are just recalibrating it by adjusting the off temp to a higher heat exchanger setting.

Last edited by how; 01-07-2013 at 01:07 AM.
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Old 01-07-2013, 12:58 AM   #28
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Furnace clicking noise, blower runs continuously


and that furnace is way to old to play with ..and very inefficient.....
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Old 01-07-2013, 01:03 AM   #29
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Furnace clicking noise, blower runs continuously


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As the control is getting weaker you are needing to turn the arm to a higher control temp to get it to turn the fan off at a higher exchanger temp as the furnace is cooling down. You are only compensating for a fan control whose temp reading is out of calibration.
Your faulty off fan control setting is presently reading that the exchanger temp is lower than room temp so the fan never shuts off. Raising the temp off setting will turn off the fan earlier (at a warmer temp) by creating the needed temp differential that has been lost through wear and tear.

It a lousy explanation. Too late to redo it. Hope it makes sense.
Cheers
Thanks, you've explained just fine. Looks like I'm gonna need to change both limit and fan off temp switches. That explains the intermittent problem with the fan because sometimes it shuts off fine. Definitely the switch is getting weak and out of calibration.
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Old 01-07-2013, 01:06 AM   #30
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Furnace clicking noise, blower runs continuously


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and that furnace is way to old to play with ..and very inefficient.....
Yes, it's pretty old but runs fine. I agree with you about the efficiency. Not really economical to change the furnace now cuz the house is just as old and inefficient. Not enough insulation and lots of areas where heat escapes. Just gonna get by for several more years and looks like the house is gonna need to be torn down and rebuilt.

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