Furnace Is Not Responding To Call For Heat.. - HVAC - DIY Chatroom Home Improvement Forum

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Old 11-10-2012, 09:45 PM   #1
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Furnace is not responding to call for heat..

Just spent 150 buck for a service man to come look at my furnace and to find "nothing" wrong. But something its really wrong and I can't seem to find it... So i'm coming here to seek help from the many pro here.

Background on my furnace:
-Came with the house that was newly built 3 years ago.
-American Standard Freedom 90 Single Stage. Does not know the year it was made but would think pretty recent.

The problem:
Thermostat is switch to Heat. Fan is on Auto. Call for heat by increasing to desired temperature. The word HEAT is blinking on the screen which mean its calling for heat from the furnace. No heat comes out of any of the vents. Went downstair to check the service light and noticed it blinking 3 times with a pause in between. Shut off system with the emergency switch. Turn it back on and the furnace ignite and heats the house up to the temperature set. Furnace shuts off and the light is blinking normal no call for heat. Temperature in the house drops and the thermostat calls for heat again to maintain the desired temp. No heat comes out of vent. The light is blinking 3 times again. Have to turn system off and on again to get the furnace to ignite and heat the house.

What I have done:
I have clean and clear of all the hoses that's connected to the pressure switch. I've checked all the fan and its working. I've made sure that there's nothing blocking any vent. The service man also acknowledge that everything is maintain correctly and that it suppose to work normally.

However, its still not working and I really don't to get up in the middle of the night to reset the system just so my family wont' freeze in the morning. Please can someone tell me what else should I check? Any help is totally appreciated!


hoaindao is offline   Reply With Quote
Old 11-10-2012, 10:12 PM   #2
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This post:
American Standard Freedom 90 error
from last year identified a recalled circuit board.

Maybe pros can advise if yours is faulty.

Be prepared and have board model # ready.


diyorpay is offline   Reply With Quote
Old 11-11-2012, 02:08 AM   #3
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Check what those three blinking lights mean on the legend inside the furnace.
I think that it might mean a pressure switch problem.
A common thing to check is a blockage inside the hose bib of the inducer assy that leads to the PS. Take off the PS line to the inducer and use a straightened paper clip to see if its obstructed inside that inducer hose bib. Some folks use a drill bit to clear it if there is a blockage inside.

Did the tech use a manometer to measure the vaccum the inducer was producing to compare it to the inducer or the PS threashold? If this problem was happening when he's was there then he should have been able to isolate the cause with a manometer and an electrical meter.

Last edited by how; 11-11-2012 at 02:17 AM.
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Old 11-11-2012, 08:48 AM   #4
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Sounds like pressure switch not returning to normally open position at end of cycle?
Setup a nice comfy chair infront of furnace and watch it run thru a couple of cycles to
see when the problem happens.
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