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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

Flawless transaction. They did exactly what they promised, showed-up on time, cleaned-up, and were highly professional. Highly recommended.

by Bill Edmondson on Twintech Heating and Cooling

Salesperson and 2 man installation team were all professional and
knew their stuff. All three were friendly and helpful, answering all
my questions. The quality of their work demonstrated their experience
and expertise in their field.

by Private User on Twintech Heating and Cooling

A dear late cousin of mine recommended this company and I have been happy with the service.

by Private User on Twintech Heating and Cooling

We are very pleased with the work done by Twintech. They were very professional from start to finish. Dave came to our home and gave us a very competitive quote for new high efficiency furnace and air conditioner. The installers were very courteous and professional. We would highly recommend them.

by W1n5t0n1987! on Twintech Heating and Cooling

Great experience getting an old furnace replaced.
Sales Guy (Dave) was great - honest, responsive, and friendly.
The work itself was done quickly and we are very happy with the outcome, thank you! We recommend TwinTech!

by Private User on Twintech Heating and Cooling

This review is late coming so my apologies to the amazing Twin Tech team! I contacted Dave at Twin Tech for a quote this past Feb (as I was collecting a few) and his recommendation was excellent. From the first meeting with Dave to the team installing the new furnace, not once did i feel uncomfortable . The team were extremely professional yet personable and clean and tidy. Decent companies still exist!
The new furnace just purrs and its just amazing the difference it has made!
(PS my sibling ended up getting a furnace from them as well)

by Private User on Twintech Heating and Cooling

The service was Twintech was excellent.
Dave our salesperson was easy to talk to and was professional. The unit recommended meets our needs and budget.
Greg and his team arrived on time for the installation and even got rid of the garbage the contractors left in our furnace.
Would definitely recommend Twintech.

by Steve V, Toronto on Twintech Heating and Cooling

Our old water tank was installed in 1997. Wasn't working as well as it should so we looked into a tankless as it is more efficient and a space saver! we had used Twintech in the past for a furnace cleaning and were satisfied with that so we decided to ask for a quote for the changeover. Gary arrived and provided the options and the quote fit within our budget so we decide to go with them after receiving a few alternative quotes from other companies. They did what the said would be done and it was completed within a reasonable time frame! Removal and cleanup of the old tank was seamless. We are now enjoying consistent and efficient Hot water! I recommend Twintech and would use them for future projects!

by New AC Unit + Humidifier on Twintech Heating and Cooling

One of the most honest HVAC companies out there! Dave was very helpful and informative in helping us choose a new AC unit. While they weren’t the lowest quote, we went with them because we trusted Dave and he was the most honest guy out of the companies that quoted us.
Greg and his crew who installed the unit were very professional and did a great job. If I could do it over again I would choose Twintech again.

by Private User on Twintech Heating and Cooling

Relocated and replaced our air conditioning unit. Fast, professional, and high quality service. We would definitely use them again for future projects!