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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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P, The blower runs but the fan limit switch shuts off the

Customer Question

P, The blower runs but the fan limit switch shuts off the flame after a few minutes, upper limit. I checked the voltage to the fan 110 volts high speed terminal. The fan is clean and turns freely. jumped out limit switch and flame will stay on but gets very hot. Cracked heat exchangers?
JA: Thanks. Can you give me any more details about your issue?
Customer: The blower will run constantly but does not get the temp low enough to shut the blower off. If you turn the power to the furance off and let it cool down to 100 degrees F the flame will come on, and then the blower but the temp raises very fast. Then the limit switch cut off the flame, just when the limit gets below 180 degrees the burner comes on and then heats it up for a short period and the the upper limit cuts off the burner, and then it starts over. Does not produce lots of heat to warm the house. Its a heil 7000 125,000 BTU.
JA: OK got it. Last thing — HVAC Technicians generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: HVAC
Expert:  Rick replied 1 year ago.

Is the filter clean? do you have AC?