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:
May 13, 2020
We are very happy with our new furnace. The service was excellent the guys worked 6 hours straight through and there was no mess at all they took the old furnace boxs etc with them they then explained everything to us they were very helpful and pleasant , when we need a new air conditioner we know who to call!
May 12, 2020
The crew from sales to installation was very professional and had great attention to detail
May 11, 2020
We couldnt have been more impressed with Twintech - from our first service call with Mitch who took the time to thoroughly diagnose the issue with our furnace, to Dave who proposed a well thought out solution to meet our needs and finally Greg and team who acted quickly to install given we had no heat.
We did our due diligence by soliciting quotes from alternate providers and were shocked and disappointed by the aggressive and manipulative tactics used.
Twintech was honest in their approach, detailed in their product knowledge, reasonably priced, diligent in their follow-up and valued our business.
Well done Twintech! You made this a positive experience for us and our new furnace works beautifully!
May 10, 2020
We recently purchased an Amana high efficiency furnace and humdifier through Twintech. The work was completed very professionally and the quality of the workmanship was high. There was some additional sheet metal work required to complete the installation, which they were able to complete themselves. Overall I am very pleased with the work and would highly recommend Twintech for a furnace replacement.
May 9, 2020
We were very pleased with every aspect of the work that was done. They were very professional and polite. They arrived when they said they would and job was completed on estimated time
We would highly recommend them to whoever needed a recommendation
We have a very large dog and they were very understanding and respectful of him being around
May 8, 2020
The blower on our furnace stopped working leaving us with a cold house. Dave from TwinTech responded immediately to our HomeStars service request. From beginning to end Dave was nothing but helpful, friendly and professional, he did a great job of walking us through the quote and scope of work.
The replacement of the furnace went smoothly. The Guys did a great job, everyone was very friendly and polite. There were no hiccups, or unexpected costs. The only surprise was they left the work area cleaner than it was before they started.
Was a great experience with the whole TwinTech team. Its been a couple of months since the new furnace has been installed and its working great!
May 7, 2020
I heard about TwinTech when researching new furnaces at furnaceprices.ca. After contacting them about my broken down furnace, Dave came to my house the next day to assess my situation and requirements for a new furnace. He recommended one that had stainless steel heat exchangers which sold me since my previous furnace had issues with a rusted secondary heat exchanger that had to be replaced. Dave also set me up with an appointment with an energy audit company so that I could take advantage of a rebate to help improve the energy efficiency of my home and get some money back. A few days later, Greg, Grant, and Mitch came to install the new furnace and remove the old one. When delivering and removing the furnaces, they were very careful not to damage my floors and walls, and even laid out red carpeting to protect the floors. They were very friendly and professional. The installation was completed in the time they said it would take and they cleaned up their work areas. Within a week, Dave called to follow-up to see how everything was going. I have already recommended them to several friends and family members who may need new furnaces soon.
May 6, 2020
Twintech did a great job, from Dave the Sales Rep to the Office staff and The Professional Technicians who did the installation. They were professional, courteous, knowledgable and informative. From beginning to follow up we were completely satisfied with everything. Thanks Again. Sincerely The Laytons
May 5, 2020
Great product, great service, great follow-up. The Twintech Heating and Cooling arranged removal of my existing oil tank and they installed the new gas furnace Amana (made in USA). I am very happy with the final result and support I received throughout the process. My thanks go to the entire Twintech team for their professionalism, great communication and follow-up.
May 4, 2020
We've had Twintech provide us with work in the past, for an inground pool heater and required rough-in for a new gas stove. More recently they provided the same friendly, professional, timely and clean installation of our new furnace.
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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