Durham Region Air Conditioning Repair, Service and Installation
McQuay was established in 1933. She specialized in the supply and service of air conditioning, ventilation and heating equipment, as well as in the production of heating equipment - heat exchangers and radiators.
McQuay Furnace error codes are seen in three colors, red, green, and amber/yellow. Each color will also flash a specific number of times to signify a specific error. Breaking down each color, and number of flashes, will help you solve the problem you are having with your York Furnace.
CODE: SLOW GREEN FLASH
RESULT: Normal operation
RESULT: Normal operation
CODE: SLOW AMBER FLASH
RESULT: Normal operation with call for heat
RESULT: Normal operation with call for heat
CODE: RAPID RED FLASH
RESULT: Twinning error, incorrect 24V phasing.
FIX: Check twinning wiring. Flame sense current is below 1.5 microamps
RESULT: Twinning error, incorrect 24V phasing.
FIX: Check twinning wiring. Flame sense current is below 1.5 microamps
CODE: RAPID AMBER FLASH
RESULT: Check and clean flame sensor. Check for proper gas flow. Verify that current is greater than 1.5 microamps at flame current test pad.
RESULT: Check and clean flame sensor. Check for proper gas flow. Verify that current is greater than 1.5 microamps at flame current test pad.
CODE: 4 AMBER FLASHES
RESULT: The control is receiving a "Y" signal from the thermostat without a "G" signal, indicating improper thermostat wiring.
RESULT: The control is receiving a "Y" signal from the thermostat without a "G" signal, indicating improper thermostat wiring.
CODE: 1 RED FLASH
RESULT: This indicates that flame was sensed when there was not a call for heat.
FIX: The control will turn on both the inducer motor and supply air blower. A gas valve that leaks or is slow closing would typically cause this fault.
RESULT: This indicates that flame was sensed when there was not a call for heat.
FIX: The control will turn on both the inducer motor and supply air blower. A gas valve that leaks or is slow closing would typically cause this fault.
CODE: 2 RED FLASHES
RESULT: This indicates that the normally open pressure switch contacts are stuck in the closed position.
FIX: The control confirms these contacts are open at the beginning of each heat cycle. This would indicate a faulty pressure switch or miswiring. This indicates the normally open pressure switch contact did not close after the inducer was energized.
RESULT: This indicates that the normally open pressure switch contacts are stuck in the closed position.
FIX: The control confirms these contacts are open at the beginning of each heat cycle. This would indicate a faulty pressure switch or miswiring. This indicates the normally open pressure switch contact did not close after the inducer was energized.
CODE: 3 RED FLASHES
RESULT: This could be caused by a number of problems: faulty inducer, blocked vent pipe broken pressure switch hose or faulty pressure switch.
RESULT: This could be caused by a number of problems: faulty inducer, blocked vent pipe broken pressure switch hose or faulty pressure switch.
CODE: 4 RED FLASHES
RESULT: This indicates that the main limit switch has opened its normally closed contacts.
FIX: The control will operate the supply air blower and inducer. This condition may be caused by: dirty filter, improperly sized duct system, incorrect blower speed setting, incorrect firing rate or faulty blower motor. Also, this fault code could be caused by a blown fuse located on the control board.
RESULT: This indicates that the main limit switch has opened its normally closed contacts.
FIX: The control will operate the supply air blower and inducer. This condition may be caused by: dirty filter, improperly sized duct system, incorrect blower speed setting, incorrect firing rate or faulty blower motor. Also, this fault code could be caused by a blown fuse located on the control board.
CODE: 5 RED FLASHES
RESULT: This fault is indicated if the normally closed contacts in the rollout switch opens.
FIX: The rollout control is manually reset. If it has opened, check for proper combustion air, proper inducer operation, and primary heat exchanger failure or burner problem. Be sure to reset the switch and cycle power (24 VAC) to the control after correcting the failure condition. Also, this fault code could be caused by a blown fuse located on the control board.
RESULT: This fault is indicated if the normally closed contacts in the rollout switch opens.
FIX: The rollout control is manually reset. If it has opened, check for proper combustion air, proper inducer operation, and primary heat exchanger failure or burner problem. Be sure to reset the switch and cycle power (24 VAC) to the control after correcting the failure condition. Also, this fault code could be caused by a blown fuse located on the control board.
CODE: 6 RED FLASHES
RESULT: This indicates that after the unit was operating, the pressure switch opened 4 times during the call for heat.
FIX: If the main blower is in a "Delay on" mode, it will complete it, and any subsequent delay off period. The furnace will lock out for one hour and then restart.
RESULT: This indicates that after the unit was operating, the pressure switch opened 4 times during the call for heat.
FIX: If the main blower is in a "Delay on" mode, it will complete it, and any subsequent delay off period. The furnace will lock out for one hour and then restart.
CODE: 7 RED FLASHES
RESULT: This fault code indicates that the flame could not be established. This no-light condition occurred 3 times (2 retries) during the call for heat before locking out.
FIX: Low gas pressure, faulty gas valve, dirty or faulty flame sensor, faulty hot surface ignitor or burner problem may cause this. The furnace will lock out for one hour and then restart.
RESULT: This fault code indicates that the flame could not be established. This no-light condition occurred 3 times (2 retries) during the call for heat before locking out.
FIX: Low gas pressure, faulty gas valve, dirty or faulty flame sensor, faulty hot surface ignitor or burner problem may cause this. The furnace will lock out for one hour and then restart.
CODE: 8 RED FLASHES
RESULT: This fault is indicated if the flame is lost 5 times (4 recycles) during the heating cycle.
FIX: This could be caused by low gas pressure, dirty or faulty flame sensor or faulty gas valve. The furnace will lock out for one hour and then restart.
RESULT: This fault is indicated if the flame is lost 5 times (4 recycles) during the heating cycle.
FIX: This could be caused by low gas pressure, dirty or faulty flame sensor or faulty gas valve. The furnace will lock out for one hour and then restart.
CODE: 9 RED FLASHES
RESULT: Indicates reversed line voltage polarity or grounding problem.
FIX: Both heating and cooling operations will be affected. check polarity at furnace and branch. Check furnace grounding. Check that flame probe is not shorted to chassis.
RESULT: Indicates reversed line voltage polarity or grounding problem.
FIX: Both heating and cooling operations will be affected. check polarity at furnace and branch. Check furnace grounding. Check that flame probe is not shorted to chassis.
CODE: 10 RED FLASHES
RESULT: Flame sensed with no call for heat.
FIX: Check gas valve and gas valve wiring This indicates that a primary or auxiliary limit switch has opened its normally-closed contacts and has remained open for more than five minutes.
RESULT: Flame sensed with no call for heat.
FIX: Check gas valve and gas valve wiring This indicates that a primary or auxiliary limit switch has opened its normally-closed contacts and has remained open for more than five minutes.
CODE: 11 RED FLASHES
RESULT: This condition is usually caused by a failed blower motor or blower wheel.
FIX: Cycle power (24 VAC) to the control to reset the hard lockout condition after correcting the failure condition.
RESULT: This condition is usually caused by a failed blower motor or blower wheel.
FIX: Cycle power (24 VAC) to the control to reset the hard lockout condition after correcting the failure condition.
CODE: 12 RED FLASHES
RESULT: This code indicates an open igniter circuit.
FIX: This could be a disconnected or loose wire or a cracked or broken igniter.
RESULT: This code indicates an open igniter circuit.
FIX: This could be a disconnected or loose wire or a cracked or broken igniter.
CODE: STEADY ON RED
RESULT: Control failure.
FIX: Replace control board.
RESULT: Control failure.
FIX: Replace control board.
CODE: 60-MINUTE AUTOMATIC RESET FROM LOCKOUT
RESULT: This control includes a "watchdog" type circuit that will reset from a lockout condition after 60 minutes. Operational faults 6, 7, 8 will be reset. This provides protection to an unoccupied structure if a temporary condition exists causing a furnace malfunction. An example would be a low incoming gas supply pressure preventing unit operation When the gas pressure is restored, at some point the "watchdog" would restart the unit and provide heat for the house.
RESULT: This control includes a "watchdog" type circuit that will reset from a lockout condition after 60 minutes. Operational faults 6, 7, 8 will be reset. This provides protection to an unoccupied structure if a temporary condition exists causing a furnace malfunction. An example would be a low incoming gas supply pressure preventing unit operation When the gas pressure is restored, at some point the "watchdog" would restart the unit and provide heat for the house.
CODE: IGNITION CONTROL FLAME SENSE LEVELS
RESULT: Normal flame sense current is approximately 3.7 microamps DC Low flame signal warning starts at 1.5 microamps. Low flame signal control lockout point is 0.1 microamps DC.
RESULT: Normal flame sense current is approximately 3.7 microamps DC Low flame signal warning starts at 1.5 microamps. Low flame signal control lockout point is 0.1 microamps DC.
See What Our Customers Are Saying:
Feb 13, 2019
Fantastic team. Completed the job as per the specifications and in under 3 hours. Highly recommended Twintech.
Jan 30, 2019
During the summer, I previously hired TwinTech to replace my air conditioner when it failed. They did an excellent job so when I decided to proactively replace the furnace I contacted them. The furnace I had was 22 years old and showed signs of internal leakage. It still worked but rather than wait to have it fail in cold weather, I decided to purchase a higher efficiency model before it failed and take advantage of energy efficiency rebates. TwinTech offered very useful advice on the make and model of furnace to choose including high efficiency and variable speed motor. The price was reasonable, TwinTech arrived at the allotted time, installed the new furnace (including some re-routing of exhaust lines since the existing ones were too close to other vents), removed the old furnace, tested the installation and cleaned everything up. Overall, it was a good experience, they did a great job and the new furnace is working well.
Jan 26, 2019
Greg came over at 9:30pm to rescue my daughter and I from a horrible experience with Enercare that evening. He was professional. Kind. And got us what we needed quickly and at an afford price. I would 100% recommend calling on Greg and his team for any of your heating and cooling needs in the future!!
Jan 24, 2019
Installed a great hot water heater when our old one failed. When my furnace died during cold weather they showed up quickly and my house was warm before my wife got home. :)
Jan 14, 2019
I dont usually right reviews but when you receive service like this I felt it was a must. Honest and fair. I Have 4 children and on Xmas eve my furnace stopped working and a gentleman came out and got me up and running so at least we would have heat for the holidays. As promised he would replace my furnace early in the new year. The job was completed on time, great price for quality furnace and extremely clean and professional job. Would have never known anyone was in the house. Not a spec of dust or mess from lugging out an old rusty furnace. If you have any ac or heating concerns twintech is your only option. I was royally impressed with and Im sure you will be too.
Jan 14, 2019
Class Act ! These guys were professional right from the quote stage through to installation. They know their stuff and took their time to help educate me. They take pride in their work and it shows. I would recommend TwinTech Heating and Cooling to anyone. Keep up the great work !!!
Dec 28, 2018
This Company is terrific. No high pressure sales and they deliver exactly what they promise to deliver. The new furnace is great and we now get consistent temperatures throughout the house. The installers were great and very efficient and completed the work on schedule on the promised day. Everyone representing this company was very aware of their presence in our house and worked diligently to keep our home as uninterrupted and as clean as was humanly possible. We did not need to go around the house to clean up after they left, what a nice surprise. We have had follow up by the company to ensure everything is to our satisfaction. How unusual in today's environment. The impression left by Twintech is that they care about us and our home. This is so refreshing in today's high tech world. Out thanks go out to Dave in sales and G, G, and P (the installers).
Dec 21, 2018
They were Timely and professional. They were very Knowledgeable with answering all of my questions.
Dec 23, 2018
The entire process was prompt and professional, from the initial quote to the installation of the new furnace. The team installed the new furnace and removed the old one in approx. 4 hrs. The guys were very knowledgeable and gave me lots of information. I have used Twintech before for a new A/C installation and new I was in good hands.
Dec 9, 2018
The overall experience dealing with this company was great from start to finish when getting a new furnace and ac this year. Everything was clearly explained to us during our consultation with Dave and there were no surprises with added costs. The work was done as expected and their response time to inquiries were very timely generally within a few hours or less. They are all very professional and was a pleasure to do business with them. Highly recommend to anyone looking for honest quality professional service.
See What Our Customers Are Saying:
Aug 8, 2025
We are very happy to recommend this company to everyone. Our furnace broke down on Sunday morning. We phoned them and before noon Grant the owner showed up. He worked on the furnace for about a hour not wanting to give up to fix the problem. The furnace was 17 years old. I was the one talking about replacing it. End result was the next day it was all done. On the Sunday Bob came over with heaters to warm up the house. We decided to replace the water heater at the same time. Thanks Grant for the excellent work. Thumbs up.
Aug 8, 2025
Right on time. Explained how to work the HRV in a different way so the house would not be so dry. Changed my whole house water filter for me as well. Friendly, helpful, caring service!
Feb 18, 2025
Very pleased with the professional service that TwinTech Heating and Cooling provided in replacing my furnace. I got several quotes from different service providers. Their price was excellent and they explained the features very well. We are very glad we went with TwinTech and highly recommend their services.
Feb 18, 2025
We were new homeowners in need of a second opinion. TwinTech Heating & Cooling were Amazing and professional. Very knowledgeable and great service all around. Recommend to anyone looking for honest and reliable services. Treated with respect and care. Thank you Greg, Mitch and Bob!
Feb 18, 2025
TwinTech is an excellent and honest company! I called them for a second opinion after being told by another company that I needed to replace my furnace. Turns out this was not the case at all! I did not need a new furnace. TwinTech did not push to make an unnecessary sale and saved me from a huge expense. Bob and Mitch were extremely professional and above all honest! I definitely recommend TwinTech!
Energy-Saving Tips for Summer
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - May 28, 2018
If you think that you are doing everything to possibly keep your costs down on your utility bills during the warmer months, then you should know that there is always room improvement. We have gathered some great energy-saving tips that can save mo
Read MoreWhy is My Heat Pump Beeping?
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - December 7, 2023
A heat pump beeping can be an indication of various issues, and it's important to determine the cause to address the problem properly. Here are some common reasons why your heat pump might be beeping: Error Codes: Many heat pumps are equ
Read MoreShould My Furnace Be Blowing Cold Air?
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - November 26, 2024
If your furnace is blowing cold air, it could indicate a problem that needs attention. Here are some common reasons and steps to troubleshoot: 1. Thermostat Settings Check the mode: Ensure the thermostat is set to "Heat" and not &q
Read More5 Ways to Save Energy and Cut Air Conditioning Costs this Summer
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - June 5, 2019
Do you find that your AC bills begin to rack up as soon as summer comes around During the hotter months, your air conditioning unit has to work harder to cool down your home, which can lead to expensive energy bills. We’ve come up with 5 tips and
Read More