Durham Region Air Conditioning Repair, Service and Installation
If you're looking for help fixing your Heil furnace, look no further! Our comprehensive Heil furnace repair guide will explain common issues, provide troubleshooting tips, and show you how to read your model's error codes..
CODE: Heartbeat.
RESULT: Control has 24 VAC power.
RESULT: Control has 24 VAC power.
CODE: 2 Flashes.
RESULT: Pressure switch did not open, check for obstructed pressure tubing.
RESULT: Pressure switch did not open, check for obstructed pressure tubing.
CODE: 3 Flashes.
RESULT: Pressure switch did not close, or re-opened- Check for: excessive wind, proper vent size, defective inducer motor, low inducer voltage, defective pressure switch, inadequate combustion air supply, disconnected or obstructed pressure tubing, low inlet gas pressure, restricted vent, condensate clogged.
RESULT: Pressure switch did not close, or re-opened- Check for: excessive wind, proper vent size, defective inducer motor, low inducer voltage, defective pressure switch, inadequate combustion air supply, disconnected or obstructed pressure tubing, low inlet gas pressure, restricted vent, condensate clogged.
CODE: 4 Flashes.
RESULT: Limit circuit fault-a limit or flame rollout is open. Check for: restricted vent, proper vent sizing, loose blower wheel, excessive wind, dirty filter, defective blower motor, defective switch or connections, inadequate combustion air supply.
RESULT: Limit circuit fault-a limit or flame rollout is open. Check for: restricted vent, proper vent sizing, loose blower wheel, excessive wind, dirty filter, defective blower motor, defective switch or connections, inadequate combustion air supply.
CODE: 5 Flashes.
RESULT: Abnormal flame proving signal-Flame is proved while gas valve is de-energized. Check for: leaky gas valve, stuck open gas valve.
RESULT: Abnormal flame proving signal-Flame is proved while gas valve is de-energized. Check for: leaky gas valve, stuck open gas valve.
CODE: 6 Flashes.
RESULT: Failure to ignite or flame sense lost while running. Check for: Flame sensor must not be grounded, low inlet gas pressure, oxide buildup on flame sensor, Manual valve shut off, proper flame sense microamps, gas valve defective or gas valve turned off, defective hot surface igniter, control ground continuity, Inadequate flame carryover or rough ignition, green/yellow wire MUST be connected to furnace sheet metal.
RESULT: Failure to ignite or flame sense lost while running. Check for: Flame sensor must not be grounded, low inlet gas pressure, oxide buildup on flame sensor, Manual valve shut off, proper flame sense microamps, gas valve defective or gas valve turned off, defective hot surface igniter, control ground continuity, Inadequate flame carryover or rough ignition, green/yellow wire MUST be connected to furnace sheet metal.
CODE: 7 Flashes.
RESULT: Limit circuit lockout- Lockout occurs if the limit or flame rollout is open longer than 3 minutes. Control will auto reset after 3 hours. Refer to #4.
RESULT: Limit circuit lockout- Lockout occurs if the limit or flame rollout is open longer than 3 minutes. Control will auto reset after 3 hours. Refer to #4.
CODE: 8 Flashes.
RESULT: Gas heating lockout-Control will NOT auto reset. Check for: mis-wired gas valve, defective control valve.
RESULT: Gas heating lockout-Control will NOT auto reset. Check for: mis-wired gas valve, defective control valve.
CODE: 10 Flashes.
RESULT: Polarity-Line voltage, polarity reversed. If twinned, refer to twinning kit instructions.
RESULT: Polarity-Line voltage, polarity reversed. If twinned, refer to twinning kit instructions.
CODE: 1 + 2 Flashes.
RESULT: Blower on after power up- Blower runs for 90 seconds, if unit is powered up during a call for heat (R-W closed) or (R-W) opens during blower on delay.
RESULT: Blower on after power up- Blower runs for 90 seconds, if unit is powered up during a call for heat (R-W closed) or (R-W) opens during blower on delay.
CODE: 6 + 1 Flashes.
RESULT: Ignition lockout- Control will auto-reset after 3 hours. Refer to #6.
RESULT: Ignition lockout- Control will auto-reset after 3 hours. Refer to #6.
CODE: LED Off.
RESULT: Secondary voltage fuse is open- Check for: door switch not closed, 115VAC at L1 and neutral, 24VAC RED and COM BLUE, 24V Fuse 3A, short circuit in secondary voltage (24VAC wiring).
RESULT: Secondary voltage fuse is open- Check for: door switch not closed, 115VAC at L1 and neutral, 24VAC RED and COM BLUE, 24V Fuse 3A, short circuit in secondary voltage (24VAC wiring).
CODE: LED On.
RESULT: Control circuitry lockout- Auto-reset after one hour.
RESULT: Control circuitry lockout- Auto-reset after one hour.
CODE: LED SOLID.
RESULT: Gas valve relay stuck open- Flame sense circuit failure, software check error, reset power to clear lockout, replace control if status code repeats.
RESULT: Gas valve relay stuck open- Flame sense circuit failure, software check error, reset power to clear lockout, replace control if status code repeats.
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!
Feb 18, 2025
Amazing experience with TwinTech Heating & Cooling! Their team was professional, knowledgeable, and efficient from start to finish. They installed my new furnace quickly and left everything spotless. The technicians took the time to explain everything and made sure I was comfortable with the system before they left. Great customer service and fair pricing. I highly recommend them for anyone needing HVAC services!
Feb 18, 2025
Great experience all around. Bob was sharp and easy to talk to, and Greg handled the installation perfectly. Would hire them again in a heartbeat.
Aug 17, 2024
I returned from vacation to find my AC unit on the Fritz. After calling way too many places I connected with TwinTech. Ive used the company in the past for my furnace so I was happy when I recognized Greg at my front door. Hes great and the service is always top notch. Id highly recommend using twintech for honest, superior service in the Durham region. Thanks!
Aug 13, 2024
I called Twin Tech when my air conditioning stopped working. Greg came over to diagnose the issue - the same day. He was able to diagnose the issue and resolve it quite quickly. Although it was a quick fix, Greg was very thorough in explaining the issue and provided great advice. Not to mention, I felt very comfortable having Greg in my home - which I consider very important when hiring a service provider. Twin Tech will be my go-to from now on. Thank you!!
Aug 12, 2024
Just hired TwinTech Heating & Cooling to do an A/C Unit removal & reinstall to allow for landscaping access on the side of my house, and they were wonderful!
Bob, Greg & Mitch make a great team! Quick appointment times, super knowledgeable, expert troubleshooting capabilities & very customer service oriented.
I would highly recommend them for all of your HVAC needs! Great job guys!!
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!
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