Heating, Air Conditioning, Fridge, HVAC/Gas Furance

Advertisement


Question
Amana home furnace approximately 18 years old.  The furnace will run and when the temperature reaches the set point on thermostat the fresh air intake and blower runs for about 20 seconds then shuts off.  I expect that it would need to run longer to expel the hot air out of the heat exchanger.  I do not understand why the fresh air intake would continue to run after it reaches it set point before furnace shuts off. We replaced the thermostat which did not resolve the problem.  I would greatly appreciate any suggestions or advise you may have.

Answer
Tom,

From my experience fresh air intake dampers  have an end switch ,when the damper open completly it closes the end switch and the furnace starts, typically the furnace fan has nothing to do with the fresh air damper.Your blower fan may be a TDR ( time delay relay ) type and preset from the factory,timed on and timed off. or you possibly have a temperature on/off type sensing the HX temperature, in that case the fan switch could be out of calibration.Your wiring diagram should show you your configuration.You would have to determine if your damper is powered open and powered closed or powered open spring return closed. possible the damper linkage is binding and not closing completely.

Heating, Air Conditioning, Fridge, HVAC

All Answers


Answers by Expert:


Ask Experts

Volunteer


Joe

Expertise

40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.

Experience

Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

Education/Credentials
Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

©2016 About.com. All rights reserved.