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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Aprilaire HVAC system that will not ignite, or

Customer Question

Customer: I have a Aprilaire HVAC system that will not ignite, or activate the blower. Is this because it needs a filter change? ***** *****
JA: Thanks. Can you give me any more details about your issue?
Customer: The control panel says "Service Filter". It worked fine till I turned it off for a weekend, and it's about 10 years old.
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Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Can you give me the complete model number on the furnace? It will be on a label on inside furnace panel just above burners.Remove panel to burner compartment and look inside. The model number will help me give accurate assistance for your specific unit.

Below is a link showing where to find label with model number:

Customer: replied 1 year ago.
Turns out, it's a York . Mdl #PT8A12L080UH11B
Expert:  airheatman replied 1 year ago.

Here is normal sequence of operation

a. The induced draft blower motor will start and come up to speed. Shortly after inducer start-up, the hot surface igniter will glow for about 17 seconds. b. After this warm up, the ignition module will energize (open) the main gas valve. c. After flame is established, the supply air blower will start in about 30 seconds.

The furnace has built-in, self-diagnostic capability. If a system problem occurs, a blinking LED shows a fault code. The LED can flash red, green or amber to indicate various conditions. It is located behind a clear view port in the blower compartment door. The control continuously monitors its own operation and the operation of the system. If a failure occurs, the LED will indicate the failure code. If the failure is internal to the control, the light will stay on continuously. In this case, the entire control should be replaced, as the control is not field repairable.

Let me know where in sequence furnace is failing and if we have a flash code. We will go from here.