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I have a York Hot air furnace that is fueled by natural gas. It is about 14 yrs old. I just noticed that the blower keeps on running even when the thermostat turns off. I tried turning the theromstat total off - it keeps running. The only way to turn it of is by switching the power off. I was wondering if the relay is bad or something like that.
The relay is probably stuck. Shut the power off and tap on it with a screw driver handle. This may do the trick but you still need to replace it
Could be a fan limit control depending on the model of furnace also.
Hi... I have a York Stellar Plus gas fired furnace... mine 16 years old... and I am also having a similar problem. Very intermittent for me though. Most times the furnace runs like a jewel, but occasionally the furnace fan will stick or stay on. I have to go down to it and just knock at the bottom panel where the fan sits in the bottom. I have had the limit switch replaced and have had them back to check the relay.. they say it is not that and that the relay has nothing to do with the heating part... and that everything is fine with the relay switch... there is also a button on the fan box behind the bottom door. This acts like a safety switch.. if furnace is running and I want to change the fitlers, this shuts down the whole furnace until I replace the door... thought it might be that, but apparently not... so with this sticking on with the fan, could it still be my fan relay, even though two furnace techs say it is not?? They tell me that the fan relay switch only works for the air conditioning?. how do I get them to replace the fan relay if it is this that is causing my problem... thanks... sir sam.
It sounds like you have a fan relay which controls the fan high speed and that is all, it is also used for cooling. The furnace fan on speed either comes off a PC board or a fan limit control, if it is a cam-stat fan limit control these are often the cause you are describing.Quote:
Originally Posted by Sir Sam
Quote:
Originally Posted by NorthernHeat
Hi... how do I tell the difference between the fan limit and the fan relay? And what exactely is a cam-stat fan limit control... thanks.. I have the tech cominig after work tonight.. I need to know to talk to him to get my problem fixed :-).. thanks for your help... sir sam..
A cam-stat is very similar to a fan/limit control. These are inserted in the back wall of the furnace above the burners, when the temperature get hot enough they turn on the fan, if they get to hot, they shut down the furnace. A relay for your heat is on the PC board, if your furnace has one, and then simple timing circuitry tells the relay to close and the fan to come on. I have no idea which you may have.
Quote:
Originally Posted by NorthernHeat
Hi. I do have the cam-stat limit control. A little round dial with temp settings on it to turn on fan, and off when cool and also if furnace over heats... they just replaced this.. and I am still getting the fan sticking on. I also have a medium sized box in the lower fan housing area. This is where it seems most of the fan wires lead into. I have taken off the front cover of this and there is a 2" x 2" looks like a ceramic box, where all wires lead into... looks like a relay, which tech's say it is, but only controls the fan for air conditioning... they have checked all this and says everything in that box is working OK... then on same box is a small button switch... this turns the whole system off when you remove the bottom fan housing door panel.. I would guess a safety switch... press it in and the fan and furnace will work, take panel off and button is out, then all shuts down.. I wonder if this could be causing fan to stick "on"... but I don't think so myself.. but if fan sticks on, and I give a little knock to the panel where that button is, the fan shuts off... and this is maddening as it only does it once in a while.. but if we go to work and the furnace comes on, and the fan sticks on, then the fan runs all day until I get home to knock the front panel... uses hydro.. which is going up all the time... anyway.. tech is coming tonight.. will see what he says, but I have feeling they won't find anything... thanks... sir sam..
No, it won't be the safety door switch.
Quote:
Originally Posted by NorthernHeat
Hi... the Furnace Tech came last night.. furnace finally acted up while he was there. Good news for me. He found I have a limit switch, or cam-stat, and three "relay switches". One was added when I had air con put in... he replaced the one where the heat part control for the fan leads to... so far so good... if it still does it, I am to call him.. left his card and he will replace the other... the one he took out was corroded etc.. feels it was the culprit :-)... so at least now we are getting somewhere and the problem has been found.. thanks for all of your help.. I appreciate it... will keep in touch... regards... sir sam..
You need to replace the fan limit control switch.Quote:
Originally Posted by gunther
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