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gotoman for ac
gotoman for ac, HVAC Technician
Category: HVAC
Satisfied Customers: 5175
Experience:  51 years of experience install design and repair of all makes and models of AC
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Why does our Carrier Weather maker 9200 gas furnace

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Why does our Carrier Weather maker 9200 gas furnace converted to propane (at church) will work fine except it will shut off and on. If it stays on until the thermostat shuts it off it will heat the building fine. But most of the time it will shut off for a few minutes and come back on for a few minutes never getting the room temperature high enough for the thermostat to shut the furnace off. Has been doing this for years.

What model thermostat are you using. You may want to set the cycle rate lower. Russ

Customer: replied 7 months ago.
Honeywell Round Heat/Cool Thermostat
Model# CT87N

Ok open thermostat and you will see switches. The switches should be set to off position for your furnace. Russ

Customer: replied 7 months ago.
Checked both thermostats this morning and the switches were in the off position on both thermostats.

OK problem is with furnace not thermostat. Does it ever lock out where you have to turn power off to reset it. Russ

Customer: replied 7 months ago.
No, I check the flame sensor and it was clean and the high limit control was clean appeared to be ok. Next Sunday I will measure the voltage on each side of the limit control when it shuts off to see if it is opening up and causing the furnace shut it down. I had 25.1 volts ac today when I check both sides, when I turned the furnace on.

That is a condensing furnace . Is there a float switch anywhere in that condensate line. Russ

Customer: replied 7 months ago.
I do not think there is. The furnace is at church and I have not went back up to check yet. I know there is not a pump on it . The condensation comes out threw a 1/2 inch PVC pipe to the basement drain. I see some water when heater is on and a lot when AC is on.

Ok thats good news. Eliminates float switch. If it was shutting off at furnace there would be a fault code and furnace would lockout. Sounds more like thermostat. Russ

Try thermostat switches to off on. Just checked manual that is for 90% furnaces. Russ

Customer: replied 7 months ago.
Sounds like you want me to turn both switches to the on position ,right? I will not be turning the furnace until Saturday. Will turn the switches to on then.

OK. Russ

How did it go with furnace. Russ

Customer: replied 7 months ago.
I think the problem is the limit switch. I let it run for about 6 hours and went back up to check on it. It was running for about 3 to 4 minutes and shutting down for about 3 minutes. I check with my volt meter and the limit switch was open when the burners were off. The red light was flashing code 33. I removed the washable air filter and it seem to be staying on when I left.I have washed this filter the best I can before. I am going to buy some throw a way filters the first of the week and try them.The limit switch is a 1Nt23L-3645 ;L190F-40 :HH12ZB190 ;0441R;Mexico. I assume it is working properly. I don't know how to check it for opening except to remove it and heat some water up to 190 degrees or so, check the temperature with a candy thermometer and check for continuity. Don

If this has a Air condition coil on top it may be stopped up causing limit switch to open. If it is clean bad limit switch. Russ

Customer: replied 7 months ago.
Thieves stole the condenser last June and we had to buy a new one which required a new acorn inside the furnace do to the type of gas and gas pressure. The old one was very clean and this one is about 6 months old and should be clean. Do you suggest buying a new limit switch. I seen on the internet I can get one for about 20 dollars. Don

Yes. That is good price and easy to change. Save you 175.00 service call. Russ

Customer: replied 7 months ago.
Ordered one from Amazon should get it in a week or so. Don

Great. Russ

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