Latest Discussions : HVAC

Tom Hanrahan

08:10AM | 12/29/02
Member Since: 12/28/02
24 lifetime posts
I have an outside Janitrol heating/air combo unit, referred to by the heating and air guys as a "package unit." It was installed in 1996. Two years ago I installed Hunter programmable thermostats on both my heating/air system and they have worked flawlessly. Three weeks ago, the induction fan, the fan that exhausts the air from the combustion chamber, began cyling on andoff constantly: five seconds off, thirty seconds on. teh heating and air guys tried a new circuit board to no avail and then replaced the thermostat with the original Janitrol mechanical mercury switch thermostat which ended the problem. They told me the Hunter thermostat had gone bad, possibly from a power surge.

I went to Lowe's and bought the same thermostat, installed it and when I kicked on the power, the fan began the endless cycling on and off. Obviously not the thermostat. Could the problem be inteh fan itself? It has four or five wires leadign into it and it had been locked up at the start of the season with mud daubers' nests which I had to clean out after the furnace had been trying to kick on. Is it possible some relayswitch inside the fan was fried?

Tom Hanrahan

02:41PM | 12/29/02
Member Since: 12/28/02
24 lifetime posts
Exactly what I have tried to tell my heating and air guy, but he insists that the problem HAS to be inthe thermostat. If that is so, why, when I replaced the thermostat with an identical, brand new programmable thermostat, the same model as the one that has worked flawlessly for two years, does the new one NOT work?

I challengd him to come replace the 'stat with the programmable brand he carries; I'm betting it won't work either.

Is there a way an check the induction fan to see if there is a cutoff switch inside?

CIWS

10:40AM | 01/18/03
Most typical "draft inducer" fans in Janitrol package units used a Fasco motor. These usually did not have internal overloads. If there are five wires coming from that motor, 3 of them would be 120V, Neutral, Ground. The other two are for a centrifugal switch within the motor. Throughly check your connection leading up to the motor. The motor may have a bad connection within the windings. Good Luck.

Tom Hanrahan

12:05PM | 01/18/03
Member Since: 12/28/02
24 lifetime posts
By "within the windings," do you mean inside the motor itself?

What is the solution to the problem if connections TO the motor are good? A new motor?

CIWS

04:25PM | 01/18/03
If you can verify that the leads to the motor are good and you have consitant voltage to them upon a call for heat, then yes, your motor my be failing.


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