Durham Region Air Conditioning Repair, Service and Installation
With this A/C troubleshooting guide, you can find problems with your system, fix it yourself. We will guide you through the process of identifying the problem and repairing your air conditioner.
Fault Display on the Dual 8 Numeral Tube of Outdoor Mainboard
CODE: E1.
RESULT: Actuation of high pressure switch.
FIX: Abnormality is detected when the contact of the high pressure switch opens for 3 sec. The system will be shut down. The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
RESULT: Actuation of high pressure switch.
FIX: Abnormality is detected when the contact of the high pressure switch opens for 3 sec. The system will be shut down. The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
CODE: E3.
RESULT: Actuation of low pressure switch.
FIX: When the unit runs more than 4 minutes or does not run, the low pressure switch opens for more than 3sec and the system will be shut down. The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
RESULT: Actuation of low pressure switch.
FIX: When the unit runs more than 4 minutes or does not run, the low pressure switch opens for more than 3sec and the system will be shut down. The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
CODE: E4.
RESULT: Air discharge high temperature protection of compressor.
FIX: The exhaust temperature is higher than 125C for more than 5sec, the system will be shut down. After stopping the compressor for 3 mins, if the exhaust temperature is lower than 90C for more than 5 sec, the compressor will re-start. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
RESULT: Air discharge high temperature protection of compressor.
FIX: The exhaust temperature is higher than 125C for more than 5sec, the system will be shut down. After stopping the compressor for 3 mins, if the exhaust temperature is lower than 90C for more than 5 sec, the compressor will re-start. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
CODE: F2.
RESULT: Malfunction of condenser temperature thermistor.
FIX: Malfunction of condenser temperature thermistor is detected when there is a short circuit or an open circuit in the condenser temperature thermistor for more than 5 sec. The system will be shut down. The reset for the malfunction of condenser temperature thermistor is automatic.
RESULT: Malfunction of condenser temperature thermistor.
FIX: Malfunction of condenser temperature thermistor is detected when there is a short circuit or an open circuit in the condenser temperature thermistor for more than 5 sec. The system will be shut down. The reset for the malfunction of condenser temperature thermistor is automatic.
CODE: F3.
RESULT: Malfunction of outdoor ambient temperature thermistor.
FIX: Malfunction outdoor ambient temperature thermistor is detected when there is a short circuit or an open circuit in the outdoor ambient temperature thermistor for more than 5 sec. The system will be shut down. The reset for the malfunction of condenser temperature thermistor is automatic.
RESULT: Malfunction of outdoor ambient temperature thermistor.
FIX: Malfunction outdoor ambient temperature thermistor is detected when there is a short circuit or an open circuit in the outdoor ambient temperature thermistor for more than 5 sec. The system will be shut down. The reset for the malfunction of condenser temperature thermistor is automatic.
CODE: F4.
RESULT: Malfunction of Exhaust Temp. Sensor.
FIX: If the exhaust temperature sensor is detected of open circuit 5 seconds successively after the compressor is started for 2 minutes or short circuit 5 seconds successively at any time .The system will be shut down. After the fault is eliminated, the system can automatically resume to operation.
RESULT: Malfunction of Exhaust Temp. Sensor.
FIX: If the exhaust temperature sensor is detected of open circuit 5 seconds successively after the compressor is started for 2 minutes or short circuit 5 seconds successively at any time .The system will be shut down. After the fault is eliminated, the system can automatically resume to operation.
CODE: ON.
RESULT: Normal operation.
FIX: Unit operating normally or in standby mode.
RESULT: Normal operation.
FIX: Unit operating normally or in standby mode.
CODE: H1.
RESULT: Defrost operation.
FIX 1: Power problem. Check control transformer power (24V). If power is available to demand control board and LED(s) do not light, replace control board.
FIX 2: Actuation of high pressure switch. Abnormality is detected when the contact of the high pressure switch opens for 3 sec. The system will be shut down. The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
FIX 3: Actuation of low pressure switch. When the unit runs more than 4 minutes or does not run, the low pressure switch opens for more than3sec and the system will be shut down..The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
FIX 4: Air discharge high-temperature protection of compressor. The exhaust temperature is higher than 125C for more than 5s, the system will be shut down. After stopping the compressor for 3 mins, if the exhaust temperature is lower than 90C for more than 5s, the compressor will re-start. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
FIX 5: Malfunction of exhaust Temp. Sensor. If the exhaust temperature sensor is detected of open circuit 5 seconds successively after the compressor is started for 3 minutes or short circuit 5 seconds successively at any time The system will be shut down. After the fault is eliminated, the system can automatically resume to operation.
RESULT: Defrost operation.
FIX 1: Power problem. Check control transformer power (24V). If power is available to demand control board and LED(s) do not light, replace control board.
FIX 2: Actuation of high pressure switch. Abnormality is detected when the contact of the high pressure switch opens for 3 sec. The system will be shut down. The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
FIX 3: Actuation of low pressure switch. When the unit runs more than 4 minutes or does not run, the low pressure switch opens for more than3sec and the system will be shut down..The unit will report this fault. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
FIX 4: Air discharge high-temperature protection of compressor. The exhaust temperature is higher than 125C for more than 5s, the system will be shut down. After stopping the compressor for 3 mins, if the exhaust temperature is lower than 90C for more than 5s, the compressor will re-start. For the first two faults within 30 minutes, the unit can be recovered automatically. If over three times, the unit cannot be recovered automatically.
FIX 5: Malfunction of exhaust Temp. Sensor. If the exhaust temperature sensor is detected of open circuit 5 seconds successively after the compressor is started for 3 minutes or short circuit 5 seconds successively at any time The system will be shut down. After the fault is eliminated, the system can automatically resume to operation.
See What Our Customers Are Saying:
Apr 28, 2022
I left a live chat message on their website that my air conditioning was not working. Within 1hr a representative called me to discuss my options.
The next day he came to the house to review my needs and give me a price for a new system. Price quoted was less than I expected and the installation was completed the following day. I found their salesman and the installers very knowledgeable and easy to deal with. All my questions were answered. Everything was properly explained in regards to what unit was needed and why, along with instruction where needed for use.
The installers made sure everything was working properly before they left.
Apr 28, 2022
This is to thank Twintech Heating and Cooling for their exceptional and timely service. Mitch, their technician was very courteous and generous with his time right from his first meeting with us. He not only took the time to check everything but also educated us on why we needed what he recommended. Greg and Mitch graciously accommodated us on our requested day and time for job to be done. They were both very courteous and responsive to our needs and special requests especially in a tight spot. The job was finished neatly and on time. Thank you Twintech for your great service !
Apr 28, 2022
They came the day and time they had planned for us and were very fast and efficient! The AC works amazing and it is amazing during the heat of the summer we have already got! Thanks for everything you did for us!
Apr 28, 2022
Would recommend this company to friends and family in a heartbeat. Very professional , on time and left no mess when the job was done.
Apr 28, 2022
Great customer service. Responsive and professional. I would highly recommend Twintech, I used them previously for repair service and a new air conditioner- very satisfied.
Apr 5, 2022
Our air conditioner failed. Made a call and within 15 min a technician was at our door.
The issue was fixed and many suggestions were provided.
Thanks to Mitch. Great service !
Apr 5, 2022
Our furnace was rattling, as soon as we put our air conditioner on this past week. We had researched looking for a company that was Registered with Better Business Bureau, and this company TwinTech, had A+ Rating. Scott, was immediately helpful via text/phone and sent his technician as soon as he was able...Mitchell/technician provided great professional service. Thank you TwinTech.
Sean and Debbie
Apr 5, 2022
I contacted various companies when looking to install a new furnace and I found Twintech to be transparent with their communication and approach. They had options to suit my various requirements and the price vs quality was very good. The after installation communication was also very good and they answered all queries I had.
Apr 5, 2022
My furnace broke down last month. The team was quick to respond, courteous, professional and mindful of COVID-19 concerns. I highly recommend them if you are considering replacing or servicing your HVAC equipment.
Apr 5, 2022
I was very happy with the installation and price. I would definitely recommend. Thank you Twintech.
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!
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