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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 Private User on Twintech Heating and Cooling

Excellent job. Excellent service. Competitive price. Its rare to find a company with the knowledge and professional results we have experienced with Twintech. The clean and neat installation with attention to detail and drop sheers to respect our property is a clear indication of Twintechs high level of integrity. The 1-1/2 gas line upgrade they did for our pool 3 years ago was awesome. Can't say enough. Thank-you Twintech.

by Private User on Twintech Heating and Cooling

Twitch did a great job with the installation of our new furnace. I really appreciated their honesty and I could trust what they were telling me. Another company tried to suggest significantly more work at a greater cost claiming it was necessary to meet current building code. Twintech is very fair. All staff I meet were friendly, polite and trustworthy. I would recommend Twitch for a furnace.

by Private User on Twintech Heating and Cooling

This is a professional team that's easy to deal with. I would strongly recommend them

by hj.taggart in OSHAWA on Twintech Heating and Cooling

Very professional firm from start to finish!
They removed the old oil tank and furnace. They installed air conditioning and a new propane furnace.
Professional installation, on time and no mess.
Very pleased with their work and would highly recommend the company. Our house is three stories so they spent the time to do all the calculations to make sure we would have great performance on each floor.
Thank you again!

by susieschoeppler in Oshawa on Twintech Heating and Cooling

Upon a routine yearly maintenance, it was discovered there was a leak in the heat exchanger and a I needed a new furnace. I know nothing about these things and was completely stressed out. The company I had the maintenance plan with quoted me a huge number to rent a furnace, I just wanted to cry. Then I spoke to Dave at Twintech. He was so knowledgeable and calming, provided me a fair quote and within a few days I had an amazing crew show up to my house and install my new energy efficient furnace! I have already recommended these wonderful people at Twintech to a good friend of mine. Thank you Twintech!!

by Private User on Twintech Heating and Cooling

Great service and great people to deal with, from sales to installer. I highly recommend this company.

by GR from Oshawa on Twintech Heating and Cooling

Twintech replaced our aging furnace and air conditioner recently. I highly recommend this company. Their quote was competitive, they were on time and respectful of our home and extremely professional. From the salesman to the installers and the owner who followed up afterward to ensure we were satisfied, we are very pleased with the service. We are looking forward to working with this company for all of our HVAC needs for the years to come. Excellent workmanship and service!

by nathans in Scarborough on Twintech Heating and Cooling

We wanted to get our AC replaced as it was 22-years old and added to this our furnace was costing more and more to repair. So, we decided to get both the furnace and AC replaced.

After going through a few quotes and product reviews we decided to go with Twintech. The three-men crew arrived early in the morning, wasted no time and got to work right away. By 2:00 pm, they were all done. I’ve found their work to be top notch and they were completely professional. I had all my questions answered to my satisfaction both during the progress of their work and at end.

I have pleasure in recommending Twintech to anyone who is looking to get their furnace or Ac replaced

Nathan S.

by Private User on Twintech Heating and Cooling

Our air conditioner died On a Saturday and within hours Dave came out to take a look and discuss replacement/repair options.
The new air conditioner was installed on the Wednesday. The new unit was installed quickly. The installers were friendly and cleaned up afterwards.
We noticed a slight leak around the furnace that night and they came out the next day and fixed the issue. It has been working great and is quieter than our previous unit.
Very satisfied and would highly recommend TwinTech.

by Nancy in Toronto on Twintech Heating and Cooling

I contacted TwinTech to replace my 20-year old A/C. Dave, their service rep, promptly replied and was at my home within 2 hours. He was friendly and knowledgeable and didn't try to upgrade or oversell their A/C units but suggested the best fit for my small 1000 feet bungalow. Although this was during a heatwave and very busy, they were able to fit me in 2 days later. The TwinTech crew installed a 1.5 ton Ducane A/C unit that is now running smoothly while maintaining a constant cooling temperature. The crew were very courteous, professional and efficient and I will definitely recommend TwinTech to family and friends. I much appreciated your great service.
Nancy M., Oshawa