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Furnace Trade-In

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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 Darcy from Pickering on Twintech Heating and Cooling

This company was great to deal with. Our furnace went down and they installed a new furnace the next day with a lot of professionalism!

by gillian hooton from Uxbridge on Twintech Heating and Cooling

Finally! An honest company with highly knowledgeable and informative staff. Had a furnace service and found multiply errors in our system from an amateur installer. Very fair price to correct problems and will definitely use again.

by dflynn in Ajax on Twintech Heating and Cooling

Had to replace the heating & a/c unit in a condo apartment dwelling. this company recommended by the property manager and president of the condo building. found their workmanship and attention to details very good and very thorough. were able to resolve small problems and situations and happy to feel the heat in my unit. it's pricey, but happy was done by a very professional service. thank you.

by alisiena from Toronto on Twintech Heating and Cooling

Fantastic team. Completed the job as per the specifications and in under 3 hours. Highly recommended Twintech.

by David from Toronto on Twintech Heating and Cooling

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.

by Jaime-Lynne in Pickering on Twintech Heating and Cooling

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!!

by Matt C. Oshawa on Twintech Heating and Cooling

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. :)

by B Davis in Pickering on Twintech Heating and Cooling

I don’t 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 I’m sure you will be too.

by stan.marosek from Ajax on Twintech Heating and Cooling

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 !!!

by W. Lacombe in Pickering on Twintech Heating and Cooling

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).

See What Our Customers Are Saying:

by Trevor Owens on Twintech Heating and Cooling

I returned from vacation to find my AC unit on the Fritz. After calling way too many places I connected with TwinTech. I’ve used the company in the past for my furnace so I was happy when I recognized Greg at my front door. He’s great and the service is always top notch. I’d highly recommend using twintech for honest, superior service in the Durham region. Thanks!

by Nicole Alain on Twintech Heating and Cooling

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!!

by Courtney Parkes on Twintech Heating and Cooling

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!!

by Jacqueline Graham on Twintech Heating and Cooling

Twintech Heating & Cooling installed my furnace in 2022 and in fall of 2023 installed my Panasonic Heat Pump. Greg and Mitch did a great job. Helped me through the rebate process. Super happy with the Heat Pump. Only used my furnace 5 times this winter. Energy bills lower, carbon emissions lower.Thank you Twintech. I recommend highly!

by Bill Grainger on Twintech Heating and Cooling

Just had a new furnace installed by Twintech. I can’t express how great these guys are at what they do. From the sales to installation they were professional all the way. Very reasonable pricing and courteous during the installation and willing to answer any questions I had. Highly recommended !!!

Increasing the Longevity of Your Heat Pump

  • SUBMITTED BY:
  • TWINTECH HEATING & COOLING
  • - October 30, 2023

Increasing the longevity of your heat pump involves regular maintenance and adopting good practices to ensure optimal performance. Here are some tips to help extend the lifespan of your heat pump: Regular Maintenance: Clean or Replac

Read More

What Parts of My AC Can Be Replaced?

  • SUBMITTED BY:
  • TWINTECH HEATING & COOLING
  • - April 8, 2024

In an air conditioning system, various components can be replaced depending on the type of issue you're experiencing or the maintenance required. Here are some common parts that can be replaced in an AC system: Air Filters: These should

Read More

What is a Heat Pump and How Does it Work?

  • SUBMITTED BY:
  • TWINTECH HEATING & COOLING
  • - July 31, 2019

A heat pump is an electrical device that pulls heat from one place and transfers it to another. This type of device has been used in Canada and around the world for decades. Both refrigerators and air conditioners use this type of device. Do not

Read More

My Panasonic Heat Pump Suddenly Shut Off

  • SUBMITTED BY:
  • TWINTECH HEATING & COOLING
  • - January 21, 2024

If your Panasonic heat pump has suddenly shut off, there are several potential reasons for this issue. Here are some troubleshooting steps you can take to identify and possibly resolve the problem: Check the Power Supply: Ensure that

Read More