york Diamond 80 furnace blows cold air


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Old 11-14-10, 07:15 AM
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york Diamond 80 furnace blows cold air

Hi,
we have York Diamond 80 furnace. Thermostat is set at 69 degrees and the air that comes out of the vents is not very warm - it's cold. So far I have replaced control board (the fan would run non stop), air pressure switch (that's what error code was) and limit switch, cleaned the flame sensor. The furnace ignites and stays lit as it supposed to but no warm air. Can somebody tell what else could be wrong? Thank you
 
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Old 11-14-10, 08:04 PM
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Is the A/C unit outside running?
 
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Old 11-15-10, 06:34 AM
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No, the A/C unit does not run. The flame is on but the hot air does not reach rooms
 
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Old 11-15-10, 09:28 AM
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this just started after you replaced the board?

The blower speed may be set too high that air hasn't had a chance to "warm" up over the heat exchanger.

What temp reading are you getting at the vents?

Furnace run a long cycle, or cycle on and off pretty often?
 
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Old 11-15-10, 10:29 AM
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I replaced the board in september while we were running ac. I had no issues after that.
How could I see what is the setting for blower? I should clarify - the air coming out of the vents is not ac cold but it's barely warm or neutral which maintains the rooms temperature.
The furnace runs for maybe 3-4min and shut off for 10-15 or so.
 
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Old 11-15-10, 05:22 PM
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Depending on where you live, you may or may not even have a problem, depending on the outside temperature, soley based on what you are saying.

One of the key questions here is for me to ask if when you have the stat set to 69, if the house is able to maintain 69, with that cycling pattern you mention?
 
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Old 11-15-10, 08:34 PM
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Originally Posted by vytama View Post
The furnace runs for maybe 3-4min and shut off for 10-15 or so.
Wow, that is a short cycle! What is the temps outside?

Also, what is the make/model of the t-stat? With that short of cycle, the system hasn't had a chance to "warm" up.
 
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Old 11-16-10, 11:54 AM
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I live in PA - temperatures are about 33-36 at night and 50s during the day. house is able to keep 69 degrees inside according to thermostat. The themostat is Honeywell, I do not have the model now, but it's digital. I tested it before replacing control board, it was fine (at least what voltmeter showed)
 
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Old 11-16-10, 04:08 PM
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So it is not that cold out. Meaning it is easier to see (than on a below 0 day) why the furnace only runs a short time.

Well insulated house.

Thermostat 'swing temperature' or 'cycles per hour' setting at a minumum.

Heat flow getting to thermostat too easily from some source.

Large furnace.

(Those can be some of the causes.)
 
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Old 11-16-10, 04:17 PM
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Turn the thermostat up to 80-85 degrees and observe the furnace to see if the burners shut off or if they run continuously.

Also, what is the temperature of air as it comes out of a warm air vent? What is the temperature of air going into a return air vent?
 
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Old 11-16-10, 04:55 PM
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Go into the stat CPH/Equipment type, and set it to 3 if it's not there.
 
 

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