Durham Region Air Conditioning Repair, Service and Installation
The codes are flashed by a series of short and long flashes of the status light. The short flashes indicate the first digit in the status code, followed by long flashes indicating the second digit of the error code.
CODE: On solid, no flash.
RESULT: None.
FIX: Normal operation.
RESULT: None.
FIX: Normal operation.
CODE: Rapid continuous flashing.
RESULT: Standard Thermostat Control 288ANA/180ANA only.
FIX: Unit being controlled by standard thermostat inputs instead of Evolution Control. Only high stage operation is aveliable. This operating mode should be used in emergency situations only.
RESULT: Standard Thermostat Control 288ANA/180ANA only.
FIX: Unit being controlled by standard thermostat inputs instead of Evolution Control. Only high stage operation is aveliable. This operating mode should be used in emergency situations only.
CODE: 1 pause.
RESULT: None.
FIX: Normal operation.
RESULT: None.
FIX: Normal operation.
CODE: 2 pause.
RESULT: None.
FIX: Normal operation.
RESULT: None.
FIX: Normal operation.
CODE: 16.
RESULT: System Communications Failure.
FIX: Communication with User Interface lost. Check wiring to UI, indoor and outdoor units.
RESULT: System Communications Failure.
FIX: Communication with User Interface lost. Check wiring to UI, indoor and outdoor units.
CODE: 25.
RESULT: Invalid Model Plug.
FIX: Control does not detect a model plug or detects an invalid model plug. Unit will not operate without correct model plug.
RESULT: Invalid Model Plug.
FIX: Control does not detect a model plug or detects an invalid model plug. Unit will not operate without correct model plug.
CODE: 31.
RESULT: High Pressure Switch Open.
FIX: High - pressure switch trip. Check refrigerant charge, outdoor fan operating and coils for airflow restrictions.
RESULT: High Pressure Switch Open.
FIX: High - pressure switch trip. Check refrigerant charge, outdoor fan operating and coils for airflow restrictions.
CODE: 32.
RESULT: Low Pressure Switch Open.
FIX: Low - pressure switch trip. Check refrigerant charge and indoor air flow.
RESULT: Low Pressure Switch Open.
FIX: Low - pressure switch trip. Check refrigerant charge and indoor air flow.
CODE: 45.
RESULT: Control Fault.
FIX: Outdoor unit control board has failed. Control board needs to be replaced.
RESULT: Control Fault.
FIX: Outdoor unit control board has failed. Control board needs to be replaced.
CODE: 46.
RESULT: Brown Out (230v).
FIX: Line voltage < 187v for at least 4 seconds.
RESULT: Brown Out (230v).
FIX: Line voltage < 187v for at least 4 seconds.
CODE: 47.
RESULT: No 230v at Unit Measured at L1 and L2 on circuit board.
FIX: There is no 230v at the contactor when indoor unit is powered and cooling/heating demand exists.
RESULT: No 230v at Unit Measured at L1 and L2 on circuit board.
FIX: There is no 230v at the contactor when indoor unit is powered and cooling/heating demand exists.
CODE: 53.
RESULT: Outdoor Air Temp Sensor Fault.
FIX: Outdoor air sensor not reading or out of range.
RESULT: Outdoor Air Temp Sensor Fault.
FIX: Outdoor air sensor not reading or out of range.
CODE: 55.
RESULT: Outdoor Coil Sensor Fault.
FIX: Coil sensor not reading or out of range. Ohm out sensor and check wiring.
RESULT: Outdoor Coil Sensor Fault.
FIX: Coil sensor not reading or out of range. Ohm out sensor and check wiring.
CODE: 56.
RESULT: Thermistors out of range.
FIX: Improper relationship between coil sensor and outdoor air sensor. Ohm out sensor and check wiring.
RESULT: Thermistors out of range.
FIX: Improper relationship between coil sensor and outdoor air sensor. Ohm out sensor and check wiring.
CODE: 71.
RESULT: Low Stage Thermal Cut out.
FIX: Compressor operation detected then disappears while low stage demand exists. Possible causes are internal compressor overload trip or start relay and capacitor held in circuit too long.
RESULT: Low Stage Thermal Cut out.
FIX: Compressor operation detected then disappears while low stage demand exists. Possible causes are internal compressor overload trip or start relay and capacitor held in circuit too long.
CODE: 72.
RESULT: High Stage Thermal Cut out.
FIX: Compressor operation detected then disappears while low stage demand exists. Possible causes are internal compressor overload trip or start relay and capacitor held in circuit too long.
RESULT: High Stage Thermal Cut out.
FIX: Compressor operation detected then disappears while low stage demand exists. Possible causes are internal compressor overload trip or start relay and capacitor held in circuit too long.
CODE: 73.
RESULT: Contactor Shorted.
FIX: Compressor voltage sensed when no demand for compressor operation exists. Contactor may be stuck closed or there is a wiring error.
RESULT: Contactor Shorted.
FIX: Compressor voltage sensed when no demand for compressor operation exists. Contactor may be stuck closed or there is a wiring error.
CODE: 74.
RESULT: No 230v at Compressor.
FIX: Compressor voltage not sensed when compressor should be starting. Contactor may be stuck open or there is a wiring error.
RESULT: No 230v at Compressor.
FIX: Compressor voltage not sensed when compressor should be starting. Contactor may be stuck open or there is a wiring error.
CODE: 75.
RESULT: Low Stage Did Not Start.
FIX: Specified start voltage at VR terminal was not achieved in low stage. Start relay was de-energized after 1 second.
RESULT: Low Stage Did Not Start.
FIX: Specified start voltage at VR terminal was not achieved in low stage. Start relay was de-energized after 1 second.
CODE: 76.
RESULT: Low Stage Did Not Start 3 times.
FIX: For 3 consecutive low stage starts, the specified start voltage at VR terminal was not achieved and start relay was de-energized. Low stage locked out for 30 minutes.
RESULT: Low Stage Did Not Start 3 times.
FIX: For 3 consecutive low stage starts, the specified start voltage at VR terminal was not achieved and start relay was de-energized. Low stage locked out for 30 minutes.
CODE: 77.
RESULT: High Stage Did Not Start.
FIX: Specified start voltage at VS terminal was not achieved in high stage. Start relay was de-energized after 1 second.
RESULT: High Stage Did Not Start.
FIX: Specified start voltage at VS terminal was not achieved in high stage. Start relay was de-energized after 1 second.
CODE: 78.
RESULT: High Stage Did Not Start 3 times.
FIX: For 3 consecutive high stage starts, the specified start voltage at VS terminal was not achieved and start relay was de-energized. High stage locked out for 30 minutes.
RESULT: High Stage Did Not Start 3 times.
FIX: For 3 consecutive high stage starts, the specified start voltage at VS terminal was not achieved and start relay was de-energized. High stage locked out for 30 minutes.
CODE: 81.
RESULT: Low Stage Thermal Lockout.
FIX: Thermal cutout occurs in three consecutive low/high stage cycles. Low stage locked out 4 hours or until 24v power recycled.
RESULT: Low Stage Thermal Lockout.
FIX: Thermal cutout occurs in three consecutive low/high stage cycles. Low stage locked out 4 hours or until 24v power recycled.
CODE: 82.
RESULT: High Stage Thermal Lockout.
FIX: Thermal Lockout occurs in three consecutive high/low stage cycles. High stage locked out for 4 hours or until 24V power recycled.
RESULT: High Stage Thermal Lockout.
FIX: Thermal Lockout occurs in three consecutive high/low stage cycles. High stage locked out for 4 hours or until 24V power recycled.
See What Our Customers Are Saying:
Aug 26, 2022
This is the second time we have had Twintech to our house. A couple of summers ago they were in for an issue with our air conditioning. This time it was our furnace having an issue. It was shutting off randomly and not coming back on. Greg came right away and took the time to investigate thoroughly and explain what was going with the furnace. Both times I have been thoroughly impressed with their speed, customer service, and quality of work. I HIGHLY recommend Twintech.
Aug 24, 2022
Extremely happy.
So we were in no rush to replace our old units and took the time to do some research and get a number of quotes.
Twintech came in at around the middle of the pack for price but what convinced us to go with them was Bob, the representative that came to our house. Bob was by far the most professional of all the reps that we met with. He took the time to explain everything, what would work best for us and why. He really did seem very knowledgeable and enthusiastic about his stuff.
As promised on the day of install the crew showed up on time and got to work with minimal impact on us
..they were professional, clean, tidy and got the system up and running ahead of schedule...they made a couple of adjustments to the system to optimize it for our house.
The crew left the house clean and tidy.
Bob the rep showed up to check in and give us a few tips ..
It's been a week since install and all is good.
Our overall experience with Twintech has been excellent from start to finish and I wouldn't hesitate to recommend them.
Thank u.
Aug 23, 2022
It was a refreshing experience interacting with the Twintech team. From Bob, the sales consultant, who articulated in layman's terms all the options available and reasons for making any selection. This was done without the prevailing pressure tactics so commonplace today.
Before proceeding Mitch, the technician, at our request conducted a service check on our 30 yr old furnace. His report was positive indicating no urgency to replace it. Again no pressure tactics.
Three days after first meeting with Bob, the installation team of Greg and
Spencer completed the installation within the planned time frame.
A very professional, courteous and transparent team which delivered on their promise. I highly recommend Twintech.
Aug 22, 2022
Initial contact with sales resulted in an immediate response, which led to a timely installation. Both sales and installers were all very professional. I have no hesitation in recommending TWINTECH.
Aug 21, 2022
I had a great experience with TwinTech. The company offered a reasonable quote, and performed a quick and clean installation. The installer Greg was experienced, professional and courteous. He explained the services he performed and gave recommendations on maintain the new furnace.
The salesman Bob was honest
and professional and educated me on how to achieve optimal performance.
All communication from them was quick and they came the following day. I was pleased with the service and would recommend them.
Aug 20, 2022
From quote, to installation, to follow up, Twintech provided excellent service. I would highly recommended their services.
Aug 19, 2022
I had a really great experience with these guys. The salesman Bob was clearly very knowledgeable about everything to do with heating and cooling a home, spent a lot of time with us going over the details of the job, never rushed us and came back after the install to make sure we were happy. The installation crew was excellent, they covered the floors all the way from outside down to the basement furnace room, kept the place clean, got the work done on time and were very friendly. Ive got 15 years in the contracting/ construction industry and these guys are one of the most professional companys Ive dealt with. Great company!
Aug 18, 2022
Had great service and clean-up was good. Was happy with my salesman. They were very friendly and helpful. I needed a new furnace as our was over 20 years old. The furnace and air-conditioner work great and they are very quiet. I am very pleased with the service and product I received.
Aug 17, 2022
Met with Dave for the sales process and he was great about explaining and going over everything to us. The install happened very quickly and the team were super professional and friendly. We are very happy with this company and their services and we definitely recommend them to others. Thankful my sister recommended them to me!
Aug 16, 2022
Reviews for Twintech were good, and they did not disappoint. After an initial visit to discuss the suitable AC unit for replacement, an installation date was available in just a couple of days, and everything was installed without a hitch. Highly recommended
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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