Durham Region Air Conditioning Repair, Service and Installation
The flashing LEDs on your furnace will correspond to a specific fault code that is shown here on their diagnostic chart.
International Comfort Products Corporation (ICP) is a company that designs, manufactures and markets central air conditioning (HVAC) systems and gas and oil furnaces for use in homes and commercial buildings. It is a unit of Carrier Global Corporation and is headquartered in Lewisburg, Tennessee, United States.
CODE: LED Off
RESULT: 24 VAC or 115 VAC is off, fuse is open.
FIX: Check whether the door switch isn't closed or for a short circuit.
RESULT: 24 VAC or 115 VAC is off, fuse is open.
FIX: Check whether the door switch isn't closed or for a short circuit.
CODE: LED On
RESULT: Soft lockout, furnace control error, 1 hour delay. If code repeats immediately following power reset, then replace control.
FIX: Will auto-reset after 1 hour.
RESULT: Soft lockout, furnace control error, 1 hour delay. If code repeats immediately following power reset, then replace control.
FIX: Will auto-reset after 1 hour.
CODE: Heartbeat
RESULT: Normal operation.
FIX: N/A.
RESULT: Normal operation.
FIX: N/A.
CODE: 2 Flashes
RESULT: Pressure switch closed when should be open.
FIX: Check for an obstruction in the pressure tubing.
RESULT: Pressure switch closed when should be open.
FIX: Check for an obstruction in the pressure tubing.
CODE: 3 Flashes
RESULT: Pressure switch open when should be closed on single stage models. Low pressure switch open when should be closed on 2 stage.
FIX: Check for: excessive wind; proper vent size; defective inducer motor; defective pressure switch; inadequate combustion air supply; disconnected or obstructed pressure tubing; or restricted vent.
RESULT: Pressure switch open when should be closed on single stage models. Low pressure switch open when should be closed on 2 stage.
FIX: Check for: excessive wind; proper vent size; defective inducer motor; defective pressure switch; inadequate combustion air supply; disconnected or obstructed pressure tubing; or restricted vent.
CODE: 4 Flashes
RESULT: Limit switch or rollout open.
FIX: Check for: restricted vent; proper vent sizing; loose blower wheel; excessive wind; dirty air filter; or defective blower.
RESULT: Limit switch or rollout open.
FIX: Check for: restricted vent; proper vent sizing; loose blower wheel; excessive wind; dirty air filter; or defective blower.
CODE: 5 Flashes
RESULT: Flame sensed out of sequence.
FIX: Check for a leaky gas valve or a gas valve that is stuck open.
RESULT: Flame sensed out of sequence.
FIX: Check for a leaky gas valve or a gas valve that is stuck open.
CODE: 6 Flashes
RESULT: Failure to ignite or flame sense lost while running.
FIX: Check for: an ungrounded flame sensor; defective hot surface ignitor; low inlet gas pressure; oxide buildup; manual valve shut off; control ground continuity; inadequate flame carryover; or rough ignition.
RESULT: Failure to ignite or flame sense lost while running.
FIX: Check for: an ungrounded flame sensor; defective hot surface ignitor; low inlet gas pressure; oxide buildup; manual valve shut off; control ground continuity; inadequate flame carryover; or rough ignition.
CODE: 6 + 1 Flashes
RESULT: Soft lockout - Max of 4 trials for ignition reached (3 hour delay).
FIX: Control will auto-reset after 3 hours.
RESULT: Soft lockout - Max of 4 trials for ignition reached (3 hour delay).
FIX: Control will auto-reset after 3 hours.
CODE: 7 Flashes
RESULT: Soft lockout - Limit of roll-out switch open longer than 2 minutes (1 hr delay)(rollout switch requires manual reset).
FIX: A lockout will occur if the limit or flame rollout is open for longer than 3 minutes. Control will auto-reset after 3 hours.
RESULT: Soft lockout - Limit of roll-out switch open longer than 2 minutes (1 hr delay)(rollout switch requires manual reset).
FIX: A lockout will occur if the limit or flame rollout is open for longer than 3 minutes. Control will auto-reset after 3 hours.
CODE: 8 Flashes
RESULT: Permanent lockout - Gas valve relay contact stuck closed or mis-wired gas valve (power reset only).
FIX: Check for a miswired gas valve or a defective control valve.
RESULT: Permanent lockout - Gas valve relay contact stuck closed or mis-wired gas valve (power reset only).
FIX: Check for a miswired gas valve or a defective control valve.
CODE: 10 Flashes
RESULT: Line voltage polarity reversed. If twinned, refer to kit instructions.
FIX: Review instructions to correct polarity.
RESULT: Line voltage polarity reversed. If twinned, refer to kit instructions.
FIX: Review instructions to correct polarity.
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!
Is My Furnace Heating Unevenly?
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - March 10, 2025
If you’ve noticed that some rooms in your home feel colder than others, your furnace may be struggling with uneven heating. This can lead to discomfort, higher energy bills, and potential system damage if left unchecked. Here are some common re
Read MoreIs My HVAC System Running Inefficiently?
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - March 5, 2026
Your HVAC system plays a critical role in keeping your home comfortable throughout Ontario’s long winters and changing seasons. When it’s working properly, it should heat your home efficiently without excessive energy use or constant o
Read MoreTwintech - The Best Panasonic Heat Pump Installation in Ajax
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - September 22, 2025
When it comes to keeping your home comfortable in every season, a high-quality heat pump makes all the difference. At Twintech Heating & Cooling, we’re proud to deliver the best Panasonic heat pump installation in the Durham Region and T
Read MoreTwintech - Honesty You Can Feel
- SUBMITTED BY:
- TWINTECH HEATING & COOLING
- - October 15, 2025
When you invite a heating and cooling company into your home, you want more than just technical skill — you want honesty. That’s why homeowners across the Durham Region turn to Twintech Heating & Cooling, a family-run company built
Read More