Gas and Oil Home Heating Furnaces - ducane furnace blowing cold
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ajriggs24
01-22-06, 08:14 PM
I have a 2 year old Ducane gas furnace. I noticed it had been running for a while and realized it was not blowing hot air. The troubleshooting led is blinking 4 times. The manual says it is an open limit switch or rollout switch. I checked the rollout switches and both are closed. I cannot find the limit switch to test or reset it. Any suggestions before I call a pro tomorrow.
P.S. I did remove the filter because it was pretty dirty.
P.S. I did remove the filter because it was pretty dirty.
thermofridge
01-22-06, 08:47 PM
Try this site. http://www.ducanehvac.com/gasfurnaces.asp
ajriggs24
01-22-06, 08:51 PM
Thanks for the link thermofridge, but I already have a manual.
bolide
01-22-06, 09:07 PM
I cannot find the limit switch to test or reset it. Any suggestions?The nice thing about these is that they are all connected by wires.
So if you know where all the wires go, you aren't missing anything.
Look for a break in the voltage. "Open" means that it has voltage on one side but not the other.
So if you know where all the wires go, you aren't missing anything.
Look for a break in the voltage. "Open" means that it has voltage on one side but not the other.
ajriggs24
01-22-06, 09:12 PM
I found two wires close to the blower that appear to be the limit switch. They both have voltage. The manual says that the limit switch has a 1 hour lockout on it. The only way to turn the blower off is to turn off the breaker. As soon as you turn it back on, the fan comes on but not the burner. I am letting it run for one hour to see if it resets itself.
bolide
01-22-06, 11:43 PM
I found two wires close to the blower that appear to be the limit switch. They both have voltage.What are you using to test?
The manual says that the limit switch has a 1 hour lockout on it. The only way to turn the blower off is to turn off the breaker. As soon as you turn it back on, the fan comes on but not the burner.
One might expect that killing the breaker would have reset it the computer control. Normally if the chamber has overheated, the fan runs and the burner is locked out only while the high limit is exceeded.
The usual one-hour delay is for failure to ignite or to stay lit.
Follow the wires back to the control board to try to determine where voltage is lost.
Apparently the control thinks that the signal is not getting back.
What color is the LED?
The manual says that the limit switch has a 1 hour lockout on it. The only way to turn the blower off is to turn off the breaker. As soon as you turn it back on, the fan comes on but not the burner.
One might expect that killing the breaker would have reset it the computer control. Normally if the chamber has overheated, the fan runs and the burner is locked out only while the high limit is exceeded.
The usual one-hour delay is for failure to ignite or to stay lit.
Follow the wires back to the control board to try to determine where voltage is lost.
Apparently the control thinks that the signal is not getting back.
What color is the LED?