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York Furnace Troubleshooting & How to Guide

York Furnace Troubleshooting & How to Guide

York has mid-range and premium furnaces with AFUE (Annual Fuel Utilization Efficiency) ratings as high as 96 and 98 percent, but even their entry-level high-efficiency furnaces are rated at 95 percent. Furthermore, all their furnaces are ENERGY STAR- certified and will help users save a lot on energy bills.

But like other equipment and appliances, they are not immune to issues that can come about from their use. Some people may also have difficulties with setup, and thus limiting the ability to utilize the units to the maximum potential. In this troubleshooting and how-to guide, learn how to perform various functions on York furnaces and the steps to follow to fix some of the common issues with these units.

How to Troubleshoot York Furnace

York electric furnace

If there is no heat or cooling, check the following:

  • Check thermostat for proper settings. Make sure you set thermostat to proper setting.
  • Check circuit breakers and fuses. Reset circuit breakers if tripped and/or replace blown fuses.
  • Check outdoor unit for dirty coil (Cooling). Clean coil if dirty.
  • Check outdoor unit for snow accumulation (Heating). Remove loose snow only if there is snow accumulation.
  • Check indoor unit for dirty filter (Heating and Cooling). Clean or replace filter as necessary.
  • Check emergency heat light status on thermostat. If light is on or flashing, there is a malfunction. Troubleshoot the fault code as necessary.

If wet on floor or in the furnace:

  • Check the condensate drain and “P” trap. If blocked, remove the blockage.

If the fan does not start running:

  • Check the fuses or circuit breakers for the furnace and heat pump. Reset tripped breaker and/or replace blown fuses.
  • If fan still doesn’t come on, the fan relay, furnace control board, blower motor, or control transformer could be the problem. Troubleshoot as necessary.

If air coming out of the vents is cool:

  • Check the heat sequencer, limit control, control board, element, and wire connections. If any of these is the problem, troubleshoot and/or replace as necessary.

If the temperature rise is less than the recommended minimum:

  • Check to make sure all the elements are operating.

If the temperature rise is higher than the recommended maximum:

  • Check the blower motor for proper operation. If the blower motor is operating properly, then the speed may need to be increased.

York gas furnace

Before troubleshooting, perform the following visual checks:

  • Check to see that the power to the furnace and the ignition control module is ON.
  • The manual shut-off valves in the gas line to the furnace must be open.
  • Make sure all wiring connections are secure.
  • Review the sequence of operation. Start the system by setting the thermostat above the room temperature. Observe the system’s response. Then troubleshoot the fault codes as required to check the system’s operation.

York Gas Furnace Maintenance Tips

Performing maintenance procedures on your furnace helps ensure it runs efficiently, and for many years. Below are some basic, preventative maintenance procedures you can perform on your York gas furnace to help keep it running at its best:

  • Confirm the furnace completes a normal cycle from start-up to shutdown. Look at thermostat reading to confirm the system shuts off when reaching the high temperature set point, if the furnace shuts off before reaching the high set point, it is likely having a short cycling problem and requires service.
  • Clean dust or move objects away from the grates that supply air into each room and also remember to keep the large return grate clear and clean, as well.
  • Clear obstacles from the furnace and safety switch on the furnace door.
  • Check the vent connections in the exhaust pipe and chimney for rust or gaps.
  • Make sure your carbon monoxide monitor has fresh batteries and is operating properly.
  • Replace furnace filters annually.

How Do I Reset My York Furnace?

The York Diamond 80 furnace doesn’t have a reset button. But, you can reset the furnace from your electrical service panel. To reset a York Diamond 80 furnace, follow these steps:

  1. Go to your home’s main electrical service panel.
  2. Open the cover to the electrical service panel to expose the circuit breaker switches.
  3. Locate the circuit breaker that controls your York Diamond 80 furnace.
  4. Turn the circuit breaker switch to the “OFF” position to cutoff power to the furnace.
  5. Leave the breaker switch in the off position for about 10 seconds and switch it back to the “ON” position to restore power to the furnace and reset its circuit board.

York Furnace is Not Turning On

There could be several reasons why your York Furnace is not turning on. To troubleshoot, consider the following:

  • Check to ensure the power for your furnace is turned on.
  • At the thermostat, turn the fan to ON. The fan should run when power is being supplied to the furnace.
  • Circuit breakers in the circuit breaker box (or electrical panel) may have tripped to the OFF position. Check for tripped circuit breakers and reset them.
  • Check the SSU light switch on the gray box located on the furnace to make sure it is in the ON position.

York Furnace Troubleshooting Codes, Meaning, and Fixes

York furnace error codes are seen in three colors; red, green, and amber/yellow. Each color will also flash a specific number of times to indicate a specific error. Below is a list of the error codes, their meaning and what to do to troubleshoot and fix the problem.

  1. STEADY OFF- No 24V power to board.
  2. Check the 24 volt control circuit fuse on the board.
  3. Check the circuit breaker or fuse on the 115 volt supply power to the furnace.
  4. Check the 24 volt transformer.
  5. One green flash- Normal operation with no call for heat.
  6. Two green flashes- Indicator for “No error codes in memory”.
  7. To clear the memory, push the LAST ERROR button and hold it for more than five seconds. The LED will flash three green flashes when the memory has been cleared, then will resume the normal slow green flash after a five-second pause.
  8. Three green flashes- Indicator for “Error codes cleared from memory”.
  9. Rapid green flash- Control is in “Factory Speed-up” mode. This mode is used only during factory run-testing of the furnace.
  10. To stop this mode, cycle power to the furnace off and then back on.
  11. One amber flash- Normal operation with call for cooling.
  12. Two amber flashes- Normal operation with call for heat.
  13. Three amber flashes- Normal operation, burner is on at the end of heating cycle after wall thermostat has been satisfied.
  14. Four amber flashes- Heating capacity is reduced due to restriction in the circulating air system.
  15. Check for dirty filter or closed registers.
  16. Five amber flashes- Heating capacity is reduced due to restriction in the combustion air or vent system.
  17. Check for blocked vent/air pipe or clogged condensate drain.
  18. Above 4,000 feet altitude, this may also indicate automatic, normal derating for altitude.
  19. Six amber flashes- (Heat pump applications only) Normal operation with call for heat pump heating.
  20. Rapid amber flash- Low flame sense current.
  21. Check for dirty or mislocated flame sensor rod.
  22. One red flash- Flame is present with no power being supplied to gas valve. This can be cause by a gas valve that is slow to close or that leaks gas through the burners.
  23. Two red flashes- Pressure switch closed with inducer pressure below pressure switch set point (switch is closed when it should be open).
  24. Check pressure switch.
  25. Three red flashes- Pressure switch open with inducer pressure above pressure switch set point ( switch is open when it should be closed).
  26. Check pressure switch.
  27. Four red flashes- High limit switch open or defective temperature sensor or 24 volt fuse is open. This may be caused by a dirty air filter, improperly sized duct system, faulty blower motor, restricted circulating airflow, or an open fuse on the control board.
  28. Five red flashes- Rollout switch or condensate pressure switch is open.
  29. Check the rollout switch(es) on the burner assembly. It is a manual reset switch. To reset, push the small button in the center of the switch. If it cannot be reset or if the switch trips again, contact service.
  30. Six red flashes- Gas valve communication error. This indicates a current failure on the modulating gas valve.
  31. Seven red flashes- Lockout due to no ignition.
  32. The control will try three times for ignition. If the flame cannot be established in three tries, the control will lockout for one hour and then will try again to light.
  33. Check gas supply, igniter, gas valve, flame sensor.
  34. Eight red flashes- Lockout due to too many flame recycles.
  35. This flash code occurs if flame is lost five times during a single heating cycle. This could be caused by a faulty gas valve, low gas pressure, or dirty flame sensor. The control will lock out for one hour and then will try again.
  36. Nine red flashes- Reversed line polarity or improper grounding.
  37. Check polarity of the incoming power to the furnace.
  38. Check the grounding of the furnace, including the transformer ground and the L1 and neutral connections.
  39. Ten red flashes- Gas valve circuit shorted.
  40. Check gas valve wiring. If correct, replace gas valve.
  41. Eleven red flashes- Main blower failure.
  42. This flash code occurs when the main limit opens and fails to reclose within five minutes, indicating that the blower motor or blower when has failed.
  43. Twelve red flashes- ID plug is not present or not connected properly.
  44. Check for loose plug or loose wires in plug.
  45. Thirteen red flashes- This indicates that the high-fire pressure switch is open when it should be closed.
  46. Check for a partially blocked vent pipe, or a loose or disconnected wire, and vent pressure.
  47. Steady on red- Control fault has been detected or there is 24 volts present without 115 volts.
  48. Check that there is 24 volts and 115 volts being supplied to the board. If so, then the board should be replaced.

Where is the Pressure Switch on a York Furnace?

On a York gas furnace, the pressure switch is mounted on the draft inducer. This switch monitors the flow through the vent system. The switch will close at the beginning of each cycle when adequate combustion airflow is established. However, the pressure switch may be open under certain conditions when the burners are lit. The pressure sensor is the primary flow sensor.

Where is the Filter on My York Furnace (and How to Change it)

Regularly changing air filters will guarantee long-term efficiency for your York furnace. Doing so will ensure that your unit’s internal components, like the blower motor and the pressure tubing, continue to function at their best. The filter is usually located near where the cool air enters the furnace in the cold air return duct or the entrance to the blower chamber or sometimes in both locations.

To change the filter on your furnace, follow these instructions:

  1. Before you can replace your filter, check the access panel for the exact filter size as well as the part number.
  2. When ready, open the filter access panel.
  3. Remove the old filter.
  4. Insert the new air filter, making sure that it is installed in the same direction as the previous one.
  5. Replace the filter access panel.

How to Clean a York Furnace

It is important to clean your furnace regularly. A dirty furnace burns higher amounts of electricity and/or gas fuel as well as work less effectively than a clean furnace.

There are three basic parts of your furnace that can be impacted by the presence of dirt:

  • The filter system
  • The blower
  • The heat exchanger

To clean your York furnace effectively, follow this guide:

Cleaning the filter

  1. Start by making sure to turn off the furnace and/or HVAC system.
  2. Locate the access panel on the outside of the furnace. This is below the return-air duct, between the blower system and the duct. Usually, the filter is found inside the front of the furnace. You may need to unscrew the front panel from the furnace or unhook it to access the filter.
  3. Remove the filter and inspect it for dirt or damage. If the filter appears dirty, it needs to be cleaned or replaced, depending upon the filter type.
  4. Replace throw away filter(s) with the same size new filter. Install the clean filter with “air flow” arrow in the same direction as the air flow in your duct.
  5. For cleanable filters, you may clean with a vacuum cleaner or take them away from the unit and wash them with a garden hose. Be sure to shake off excess water and allow the filter to completely dry before re-installing the filter.
  6. Plug your furnace back and turn it on.

Cleaning the blower assembly

  1. Start by make sure that all power sources running to your furnace unit are unplugged.
  2. Remove the front panel of the furnace. You may have to loosen the screws holding the panel in place or take the panel off its supporting hinges.
  3. Inspect the entire blower assembly. If the motor and wheel are heavily coated with dust, you may brush and clean them with a vacuum cleaner. If the blower cannot be properly cleaned without removing it from the furnace, then proceed to the next step.
  4. Slide the fan unit out of the furnace. Most fans are secured to the furnace by a track, which allows it to slide in and out easily. If held by screws or bolts; remove these with a screwdriver or ratchet. If the fan is also connected by wire connections, make a note of where each wire connects to the fan before removing them. This will make it easier to reassemble the unit.
  5. Clean the blower assembly using a mild soap and water. You may also use a toothbrush to clean the fan blades and the small spaces between them.
  6. Vacuum the assembly to help ensure that all dirt is removed. If you don’t have a vacuum, you can also wipe any belts clean with a damp cloth.
  7. Once the blower assembly is clean and thoroughly dry, slide it back onto its track so that it fits into the furnace again. If you disconnected any wires, reattach them to their proper locations.
  8. Plug your furnace back and turn it on.

When cleaning the wheel, make sure you do not remove the clip on weight on the indoor fan wheel. This weight is used to balance the wheel. Moving the weight will cause the wheel to vibrate.

  • Cleaning the heat exchanger block
  • Unplug all power connections running to your furnace, and making sure the furnace is turned off.
  • Clear any dirt off of the block. Use a brush to loosen the black build-up off each chamber of the block. You may also use a damp cloth to remove the build-up.
  • Vacuum the block assembly to ensure that all the debris you loosened off of the assembly is removed.
  • Plug the furnace back in and turn it on once you have finished cleaning and vacuuming the heat exchanger block.
  • Coil cleaning

If the coil needs to be cleaned, it can be washed with water.

What Does Control Failure Mean on York Furnace?

A steady on red flash code indicates control failure. This could mean there is 24 volts present without 120 volts. It could also indicate the control board is faulty.

To troubleshoot, check that there is 24 volts and 120 volts supplied to the board. If so, then the board should be replaced.

To test the power coming into your control board:

  1. Locate the common wire on your transformer. The transformer is a small rectangular box attached to the furnace with screws. It has four wires attached to it; two high voltage wires (usually black and white) and two low voltage wires. One of those high voltage wires, usually the black wire, is the common wire. It will be labeled on the transformer (look for “COM” printed on the transformer).
  2. After locating and noting the common wire, locate the line voltage by locating the wire that runs from the door switch to the control board. It is usually labeled “LINE” on the control board. This is the wire bringing 120 volts to your furnace.
  3. Touch your voltage meter leads to the metal connector of your line voltage and common wire from step 1. You should see 120 volts or there about on your voltage meter.

To test the power in your transformer:

  1. Touch your meter leads to each of the high voltage wires on the transformer. You should see 120 volts on your meter, so you know 120 volts is coming into the transformer.
  2. Now, do it again with the low voltage wires. You should see 24 volts on your meter, so you know 24 volts are leaving the transformer.
  3. If there is 120 volts coming into your transformer, but you don’t see 24 volts coming out, your transformer is faulty and is likely the problem.

What Does the Limit Switch Do on a York Furnace?

The limit switch on a York furnace serves as a high temperature limit control. The switch will open and shuts off gas to the burners if it detects excessive air temperature in the furnace, which can be caused by any of the following:

  1. Dirty filter
  2. Failure of the circulating blower motor or wheel
  3. Too many supply or return registers closed or blocked

On a York gas furnace, the limit switch is normally mounted to the left side of the furnace vestibule panel.

York Natural Gas Furnace is Blowing Cold Air When Switch is off

If your furnace is blowing cold air, a dirty filter could be the culprit. A dirty air filter blocks airflow over the furnace’s heat exchanger, causing it to overheat. When overheating, the furnace can trip a high limit switch, causing the furnace burners to shut off. To troubleshoot, turn off your furnace at the thermostat and check the filter. If it is dirty, change it.

If you have an older furnace with a standing pilot light and the pilot light is not lit, then the furnace burners won’t light, meaning no heat. Try relighting the pilot light following these steps:

  1. Turn off your furnace. Turn your thermostat from HEAT to OFF.
  2. Find the furnace’s pilot light assembly and reset switch. The assembly and switch should be near the bottom of your furnace. You will have to open your furnace’s cover to access the reset switch.
  3. Turn the knob to “off” and wait 3-5 minutes. This will shut down the gas coming through the pilot.
  4. Turn the knob to “pilot” and press down the knob to re-start the flow of gas to the pilot.
  5. As you press the knob, hold a lighter to the pilot opening until the flame lights.
  6. Turn the knob to “on”. Your furnace should now ignite.
  7. Turn the furnace on at the thermostat. Turn your thermostat back to HEAT and ensure that the temperature is set 5 degrees below room temperature. You should be getting hot air now.

A blocked condensate line can also be the problem. If there is water pooling around the furnace, the furnace’s condensate line may be blocked. If the line gets blocked, water (condensate) backs up into the furnace, causing an overflow kill switch to shut down the furnace to prevent water damage.

How to Change Blower Motor Speed on York Furnace

Follow the instructions below to adjust fan control settings on a York furnace YP9C:


You can adjust the airflow delivered by the furnace during cooling operation to match the cooling capacity of the A/C condensing unit. To do this, move the COOL and ADJ jumper on the control board to give desired air flow.

The COOL jumper has four positions, which will deliver the airflow in cooling mode. The ADJ jumper has three positions which can be used to make further adjustments to the cooling blower airflow.

Continuous fan operation

You can adjust the airflow delivered by the furnace during continuous fan operation as desired. To do this, move the control fan jumper on the control board to give the desired airflow.

The jumper has three positions:

  • The “H” position delivers maximum airflow, 100% of the blower capacity.
  •  Position “M” delivers approximately 70% of the blower capacity.
  • Position “L” delivers minimum airflow, approximately 40% of the blower capacity.

How to Tell Manufacture Date of a York Furnace

To know the manufacture date of a York furnace, go to the outdoor cabinet of the heat pump. Look on the back side, the side facing toward the house, and you should find a nameplate. The nameplate has a list of manufacture’s specifications on it. At the top of the nameplate, you should see the manufacture’s date like a month and year.