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:
Jul 23, 2017
I have used Twintech many times over the years. They always arrive quickly and get the issue fixed. The most recent incident was when my air conditioner broke last week I called Greg at 11:30am and he was at my home by 2:30pm he had the unit fixed by 3:30pm. Twintech are very reliable and honest and they are experts in the field. I have already recommended them to many of my friends. I would not use anyone but them for my heating and air conditioning issues.
Jul 17, 2017
I would highly recommend these guys, professional, fast and competitive pricing. I moved into this place with no working AC unit with a 8 month baby, he was able to come with in a week to fix even in the busy summer days. He really values his customers , I am already recommending to my neighbors.
Jul 2, 2017
Very impressed they arrive to quote even though I had forgotten to call them back to confirm date & time. They showed the day before installation to deliver the unit. Returned the next day as promised at 9am. Project was completed in a professional manner. They even fixed a few things that they noticed were not installed correctly, or to code by previous heating & air contractors we had at our residence before. Would recommend this company to everyone!
Jun 29, 2017
Greg removed old oil furnace and oil tank from basement relocated new Napoleon propane furnace to allow duct work to be rerouted to a much more suitable location. Moved air conditioner to the new furnace. Dave recommended two available grants to assist with cost. They kept to their original quoted price which was substantially lower than a competitors for the same furnace and work. They completed the work as stated when stated and left the area clean and tidy. We are very pleased with the outcome.
Jun 28, 2017
Twintech installed a Goodman furnace and ac init. Very professional install, both units are working well.
Jun 28, 2017
We had Grant and Greg Dainty quote to replace our 20 yr old furnace. I have known them for years and have had other jobs done by them ( AC and Pool Htr). The price was very reasonable and the job was completed in one day.
Jun 23, 2017
TwinTech was the right choice. Our consultation with Dave set the tone. Professional and knowledgeable, we even received a follow-up call within hours of our install completion, wow! TwinTech arrived as scheduled to install our A/C unit. Within minutes of arrival Greg noted and explained a few out of code faults on our furnace installed by another company, problems fixed, thanks TwinTech. Greg, Grant and "Subaru" Pete were meticulous start to finish. Highly recommended!
Jun 13, 2017
Twintech replaced our aging +20 yrs old Furnace & AC with the variable high efficiency Napoleon Furnace matched with the Goodman AC. Sales guy ,Dave was great, gave a no pressure estimate, explained about the Government Rebate program which they took care of completely including arranging the home energy audit. On the scheduled day Greg and his team arrived on time, did a great job and completed the same day , extremely professional and courteous, cleaned up everything , tested the system, Greg took his time to explain the setup. Very impressed with the Napoleon Furnace 9600 which did a great job in maintaining a comfortable temperature last winter and now with the hot weather the Goodman AC cooled the house in much less time than the old AC unit could ever. From start to finish Twintech were great and have no hesitation in recommending them 100%.
Jun 13, 2017
The Twintech team did an excellent job installing our new Goodman air conditioner. They were polite and professional. Greg was knowledgeable and clearly experienced. Thank you Twintech for bringing our cooling system up to current regulations. Job well done!
Jun 11, 2017
Dave from TwinTech was very knowledgeable, professional and thorough in the buying process. He helped us to identify the best furnace for our home and our budget. When we needed a new filter a year later and seemed to have a problem finding the right one, I called Dave up and he delivered a filter to me the next day! The cost was on par with other retailers, but it was this unexpected personal service that really was impressive. The furnace? Works like a charm.
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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