furnace not turning on


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Old 10-09-03, 09:34 PM
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furnace not turning on

I had an ac installed this summer by a friends brother who is an HVAC. I tried to turn on the Heat and the furnace doesn't fire up. I am pretty good with electrical so i checked it out. I found that by tracing the wires they seem to make sense to me. I thought it odd that from the fan center that the red went to black and black to red so i tried switching with no help (they are now back as ilustrated). If at the fan center i disconect the bed and black wires and connect the red and blask ones from the fan and the plenum switch then the furnace fires right up. I have checked to make sure that the thermostat wires are connected properly at the fan center and the thermostat.

I am at a loss here as to what is wrong. I am sure it something simple that i am missing, just not sure what.

Any help appreciated.

Forgot to mention its a brand new fan center. AC and gas forced air by honeywell(the fan center that is)

Scott
 
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Old 10-09-03, 09:37 PM
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well the file is 26 kb and for some reason doesn't want to attach. If you think you can help i can e-mail you the image.

Thanks

Scott
 
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Old 10-09-03, 09:49 PM
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ahh there we go.. sorry its only a link for now.. will try to get it to display automatically
 
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Old 10-09-03, 10:13 PM
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From what I can tell, it looks like it done right.. Maybe a lable on each terminal so I know if it's on the right term..


Wht happens when you turn the fan swich on the T-Stat to "ON"?


are you gettin power to the gas valve? (24 volts), and also is the pilot lit?
 
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Old 10-10-03, 04:23 AM
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The pilot is lit.
I haven't tried just putting the fan to ON
I will try to get another pic posted tonight with lables.. I have to get going to work now

Thanks

Scott
 
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Old 10-10-03, 03:31 PM
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Not sure if this is what you meant but here is goes.
http://www.amys-sit-n-stay.com/furnace 2.jpg


Anyone else?

Thanks

Scott
 
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Old 10-12-03, 06:17 AM
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Anyone with any idea as to what the problem is?

Thanks

Scott
 
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Old 10-13-03, 01:55 AM
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Furnace not turning on

As Jay11 says have you checked that you have 24v at the gas valve?
To me it sounds like the Hi Limit is not making a circuit.
What happens if you Turn the power off Disconnect one of the wires from the HiLimit and check if you have a circuit though the HiLimit with a Meter, Or you could bridge the Hi Limit. WARNING the hilimit is line voltage so turn the power OFF (preferably pull the Plug) before Bridging and and then after checking to see what happens. DON"T touch the Hi Voltage.
Is the HiLimit an auto reset or manual?
 
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Old 10-13-03, 02:46 AM
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Furnace not turning on

Just happen to have another look at your wiring diagram and some thing funny about it struck me.
The power down to the transformer should go though the hilimit switch, The object of the HiLimit is to shut off the gas if for some reason the air is not being circulated though the furnace ie fan failure, duct blocked, Dirty filter etc etc .
The way you have shown it the power to the fan goes though the fan control switch and the HiLimit switch. Now normally we would try and keep the fan running if it overheats not shut it down?
The 40 switch should turn ON the fan while the 90 switch should turn OFF the burner in series with the loop down though the hilimit to the burner.
The blue wire from the Plenum switch should be moved to the HiLimit , The red wire should be moved to replace the blue wire.
You will need to check which switch is the 40 and which is the 90.
Normally the hilimit switch is in the pilot
thermocouple circuit but in this case it doesn't appear to be?
Hope this helps
 
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Old 10-13-03, 08:37 AM
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Looks like Norroc found it.. I was out of town for a few days so That's why I dind't reply right a way..


so turn those two wires around on the fan/limit control..
 
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Old 10-15-03, 06:18 PM
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Thanks guys. There was 24 v across, but it had been wired reverse. I switched out the wires as suggested and it still wouldn't turn on. I then checked the 24 v and it was there.. so i thought maybe its wired reverse.. switched them out and gave it juice again and she fired right up. Big thanks to all who helped.

Scott
 
 

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