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Problem: I replaced my rollout switch and the furnace still goes out after running 1/2 hour?

Problem: I replaced the rollout switch on a Honeywell furnace. It ignites and stays lite for approximately half an hour then goes out. The flames are very large. What do you think is the problem?

Answer: Without testing the components with a volt meter to see which component is causing your furnace to go off it would be a guess to what the problem is. If the rollout switch is causing your furnace to go off then you might have a heat exchanger leak (dangerous need to call HVAC Tech) or a stopped up furnace heat exchanger or furnace vent. If the furnace is going off on limit then you might have an air restriction (poor air flow through the furnace) such as a dirty filter, dirty blower wheel, slow blower motor, (capacitor could be weak, might need a new capacitor) stopped up Air conditioner evaporator coil or too much gas input. We have a picture of some limits and rollout switches below. We have a picture of me testing a rollout below. You can test a rollout or limit by setting your volt meter to “Volts AC” then with the furnace turned ON your should get 24 to 28 volts AC between each terminal of the limit or rollout to a good ground. We have a furnace troubleshooting flow chart that should help you out on the following page: Please Click here if you would like to see a furnace troubleshooting flow chart. We also have a gas furnace troubleshooting simplified page that I hope will help you out: Please Click here if you would like to see our Gas & Electric Furnace Troubleshooting Simplified page. If you have a slow blower motor and need a new capacitor we sell capacitors on the following page: Please click here if you would like to go to our Capacitors Page. I hope that you can easily find and fix the problem. Steve Arnold,

limits_three   testing rollout good


2 thoughts on “Problem: I replaced my rollout switch and the furnace still goes out after running 1/2 hour?

  1. I have a brand new 3 1/2 American standard package unit that trip right roll out limit, I replace roll out, check gas pressure, and it takes a week and trips again. There is a lot of air draft but I called ars they said that there is not such thing. need your expertly. thank you

    1. Hi Jose! I am sorry, but I do not know what could be causing your rollout to trip other than like you say a downdraft or a leaking heat exchanger. If the gas pressure on the gas valve is set too high then the excess heat from your furnace having too much gas input could cause the rollout to trip. We have a post about adjusting gas pressure on the following page: As I say in the post above it is not good when a furnace goes off with a rollout switch being tripped. Most of the time this is a sign of a stopped up vent, heat exchanger or a crack in the heat exchanger. You might want to test the rollout by placing one of your fingers near the rollout that is going off when the blower starts to see if you feel and an excessive amount of heat coming around the rollout switch. If you do feel excessive heat when the blower starts then you could have a heat exchanger problem. I hope you can easily find and fix this problem soon! Steve

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