$49 / month O.A.C Including Install
$49 / month O.A.C Including Install

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Durham Region Air Conditioning Repair, Service and Installation

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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.

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.

CODE: Heartbeat
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.

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.

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.

CODE: 5 Flashes
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.

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.

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.

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.

CODE: 10 Flashes
RESULT: Line voltage polarity reversed. If twinned, refer to kit instructions.
FIX: Review instructions to correct polarity.


See What Our Customers Are Saying:

by Eric Y, Greenbank on Twintech Heating and Cooling

Dave was great in helping me get the proper units for my property, as well as getting them installed. The installers arrived when they said they would, and completed the project on time, and professionally. If I needed another furnace, I would use Dave again.

by Ed B., Whitby on Twintech Heating and Cooling

I have known Greg and Grant Dainty for many years and have used their company for my house and business. I recommended them also for my parents and sister and they all have been very satisfied with the quality of work for a reasonable price. I just recently had them install a new HVAC system in an older house and was very pleased with their work. Craig in Pickering. After meeting with various heating and air conditioning contractors I was referred to Twin Tech Heating and Cooling through a family member. Greg and Grant arrived at my home and provided me with an estimate and a plan as to how they were going to remove and replace my furnace and air conditioner. On the day of install Greg and Grant arrived at my home on time and were very professional and extremely courteous as to any questions or concerns that I had. The removal and install was truly professional and the attention to detail was exactly what I was looking for. I’ve seen many installs from other contractors and I couldn’t be any happier to have had such a clean looking install. The sheet metal work, ducting and venting all look fantastic. Upon completion Greg and Grant left me feeling extremely happy and very fortunate of a job well done. Thanks again Twin Tech!!

by Floreene in Whitby on Twintech Heating and Cooling

My old furnace had finally broken down for the last time when contacted twintech to have a new furnace installed…They were prompt, knowledgeable and very reasonably priced. They did such a great job i tell all my friends and family about this company.

by Damien McIsaac. Ajax on Twintech Heating and Cooling

To whom it may concern, I recently had TwinTech (Greg and Grant Dainty) replace my furnace and service both my gas fireplaces and air conditioning unit. They were professional, courteous and very fair in their pricing. I would gladly recommend TwinTech to anyone needing work done. I can be contacted at 905-626-XXXX.

by Blair N. - Toronto on Twintech Heating and Cooling

My Fiancé and I have relied on Twintech Heating and Cooling now for the better part of the last 10 years. In that time, Greg has installed a furnace, an air conditioner, and a heat-pump at our residence in Toronto. In each instance Greg and his team were a pleasure to deal with. They were courteous and professional throughout the whole process and the quality of their work is first rate. Our experiences have always been extremely positive and we have referred his services numerous times to our friends and family. Without hesitation, I would recommend Greg and TwinTech Heating and Cooling to anyone looking to service or replace their existing heat/AC equipment

See What Our Customers Are Saying:

by Aaron on Twintech Heating and Cooling

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.

by Linda on Twintech Heating and Cooling

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!

by Robert Rogers on Twintech Heating and Cooling

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.

by Robert Mizuno on Twintech Heating and Cooling

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!

by Ruth on Twintech Heating and Cooling

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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