1990 Tempstar furnace heating problem


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Old 01-07-15, 04:09 PM
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1990 Tempstar furnace heating problem

I have an older 1990 tempstar furnace that been acting up as of lately.
I know its older and I don't want to replace it.

anyways what it does:
Burners light, fan switch hits temp for fan to come on, fan comes on. Both run but the fan switch will hit the high limit and kick off the burners, fan still runs.
fan switch will get to lower temp and kick the burners back on. cycles like this until it hits thermostat temp.
it has new filter, no new ducts or returns added.
What could I look for to be a possible problem.?
 
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Old 01-07-15, 04:57 PM
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Plain and simple you have an airflow problem. If you have an A/C coil in your furnace it may be plugged with dust. Make sure the returns are open and make sure too many registers aren't closed down.

Could it have been doing this for a while and you just now noticed.... or is this a new problem ?
 
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Old 01-08-15, 07:46 PM
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ok, I tried a different filter like I always used before.
no difference, all vents are open as well as returns.
I did open the lower door, held switch so it would run, it ran fine like that.
so it definitely sounds like an air issue. I will try some more tomorrow.
no a/c unit attached.
I also pulled out the coil that goes into the box and it looked clean

Its a rental, tenants recently moved out. not sure how long its been happening. sounded just recent.
 
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Old 01-10-15, 11:29 AM
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I tried all I can think of to check air flow.
No new ducts were added or taken out.
Furnace will run if I have the lower door open without over heating.
If I put the lower door on it will run until the high temp kicks out on the wheel
fan continues until it cools down, and burners will turn on again.

Any ideas ?
 
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Old 01-10-15, 11:54 AM
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Does the furnace have a PVC vent pipe or a metal vent pipe?

Were you able to view both sides of the cooling coil?

The "entering air" side of the coil is the dirty side.
 
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Old 01-10-15, 12:58 PM
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Twenty-five year old gas furnace. I trust that you have had the heat exchanger checked recently.
 
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Old 01-10-15, 03:03 PM
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metal exhaust pipe.
not sure what you are referring to as coil ?
If the dial part that goes into the heat box I took that out.
I can watch the dial move up and hit the high temp and shut the
burners off and when it cools down to point it relits burners.
The heat exchanger was my next thought to look in to. If dirty or leaking.
 
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Old 01-10-15, 08:47 PM
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Do you have air conditioning as well as heating in your home?
If you also have air conditioning, the evaporator coil could be dirty and causing this problem.













 
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Old 01-11-15, 07:57 AM
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no a/c.
its an older tempstar with pilot light, it don't have the high efficiency plastic pipes leading outside.

its just a general pilot heating system with no recent mods.
 
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Old 01-11-15, 12:41 PM
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can someone tell me what speed my fan is set up now?
and next what wire do I need to move to move it to the next higher speed
yellow and blue appear to have same terminal.
red and orange appear to be open.
 
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Old 01-25-15, 08:35 AM
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update

I have hvac tech come and take a look. He told me my chimney was plugged. Seems to be working.
 
 

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