Durham Region Air Conditioning Repair, Service and Installation
In some cases air conditioning system repair can be rather complicated for an average user. However, some of the typical problems are not that serious and don't require much more than basic skills. Even if you don't feel like troubleshooting your Rheem air conditioner on your own, you may use the check list below to gain a better understanding of the issue and not let a service company take advantage of you.
rheem A/C error codes
CODE: 0- Standby.
RESULT: No command for unit operation.
FIX: Normal operation.
RESULT: No command for unit operation.
FIX: Normal operation.
CODE: c - First Stage Cooling.
RESULT: Unit has received a command for first stage cooling.
FIX: Normal operation.
RESULT: Unit has received a command for first stage cooling.
FIX: Normal operation.
CODE: c Flashing.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) active.
FIX: The unit has received a command for first stage cooling during an active anti-short cycle timer or minimum run timer. Wait until unit timer has expired or press the TEST button to defeat short cycle delay..
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) active.
FIX: The unit has received a command for first stage cooling during an active anti-short cycle timer or minimum run timer. Wait until unit timer has expired or press the TEST button to defeat short cycle delay..
CODE: C - Second Stage Cooling.
RESULT: Unit has received a command for second stage cooling.
FIX: Normal operation.
RESULT: Unit has received a command for second stage cooling.
FIX: Normal operation.
CODE: C Flashing.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) active.
FIX: The unit has received a command for second stage cooling during an active anti-short cycle timer or minimum run timer. Wait unit timer has expired or press the TEST button to defeat short cycle delay.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) active.
FIX: The unit has received a command for second stage cooling during an active anti-short cycle timer or minimum run timer. Wait unit timer has expired or press the TEST button to defeat short cycle delay.
CODE: h - First Stage Heat Pump.
RESULT: Unit has received a command for first stage heat pump.
FIX: Normal operation.
RESULT: Unit has received a command for first stage heat pump.
FIX: Normal operation.
CODE: h Flashing.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) action.
FIX: The unit has received a command for first stage heat pump during an active anti-short cycle timer or minimum run time. Wait unit timer has expired or press the TEST button to defeat short cycle delay.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) action.
FIX: The unit has received a command for first stage heat pump during an active anti-short cycle timer or minimum run time. Wait unit timer has expired or press the TEST button to defeat short cycle delay.
CODE: H - Second Stage Heat Pum.
RESULT: Unit has received a command for second stage heat pump.
FIX: Normal operation.
RESULT: Unit has received a command for second stage heat pump.
FIX: Normal operation.
CODE: H Flashing.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) active.
FIX: The unit has received a command for second stage heat pump during an active anti-short cycle timer or minimum run timer. Wait unit timer has expired or press the TEST button to defeat short cycle delay.
RESULT: Anti-short cycle timer (3 minutes) or Minimum run timer (30 seconds) active.
FIX: The unit has received a command for second stage heat pump during an active anti-short cycle timer or minimum run timer. Wait unit timer has expired or press the TEST button to defeat short cycle delay.
CODE: d - Defrost Active.
RESULT: The unit is undergoing a defrost cycle.
FIX: Normal operation.
RESULT: The unit is undergoing a defrost cycle.
FIX: Normal operation.
CODE: t - Test Mod.
RESULT: Test Mod.
FIX: The ICC is in TEST mode.
RESULT: Test Mod.
FIX: The ICC is in TEST mode.
CODE: P - Protector Trip.
RESULT: A command for compressor operation is present but no current is measured to the compressor.
FIX: Motor protector open.
RESULT: A command for compressor operation is present but no current is measured to the compressor.
FIX: Motor protector open.
CODE: 01 - Long Run Time (Compressor).
RESULT: The compressor has continuously run for more than 18 hours in the cooling mode.
FIX: Low refrigerant charge. Air ducts have substantial leakage. Dirty indoor air filter. Dirty outdoor coil.
RESULT: The compressor has continuously run for more than 18 hours in the cooling mode.
FIX: Low refrigerant charge. Air ducts have substantial leakage. Dirty indoor air filter. Dirty outdoor coil.
CODE: 02 - High Pressure.
RESULT: Compressor limit has opened four (4) times within a call for operation.
FIX: Outdoor coil is dirty (cooling mode). Outdoor fan is not running (cooling mode). Dirty indoor coil or filter (heating mode). Indoor blower is not running (heating mode). Liquid line restriction. Excessive refrigerant charge.
RESULT: Compressor limit has opened four (4) times within a call for operation.
FIX: Outdoor coil is dirty (cooling mode). Outdoor fan is not running (cooling mode). Dirty indoor coil or filter (heating mode). Indoor blower is not running (heating mode). Liquid line restriction. Excessive refrigerant charge.
CODE: 03 - Short Cycling.
RESULT: ICC detects the run time for the past four (4) compressor or cycles is less than three (3) minutes each .
FIX: Check thermostat wire connection. Check thermostat location in zone..
RESULT: ICC detects the run time for the past four (4) compressor or cycles is less than three (3) minutes each .
FIX: Check thermostat wire connection. Check thermostat location in zone..
CODE: L4 - Locked Rotor.
RESULT: The ICC detects four (4) consecutive protector trips have occurred and the average run time for each trip is less than 15 seconds.
FIX: Bad run capacitor. Low line voltage. Excessive refrigerant in compressor. Seized bearings in compressor.
RESULT: The ICC detects four (4) consecutive protector trips have occurred and the average run time for each trip is less than 15 seconds.
FIX: Bad run capacitor. Low line voltage. Excessive refrigerant in compressor. Seized bearings in compressor.
CODE: 05 - Open circuit (Compressor Will not Run).
RESULT: The ICC has had a protector trip for longer than 4 hours.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity. Check for open compressor internal protector.
RESULT: The ICC has had a protector trip for longer than 4 hours.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity. Check for open compressor internal protector.
CODE: 06 - Compressor Open Start Circuit.
RESULT: The ICC detects current in the Run circuit but not in the Start circuit of the compressor.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
RESULT: The ICC detects current in the Run circuit but not in the Start circuit of the compressor.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
CODE: L6 - Compressor Open Start Circuit.
RESULT: The ICC detects current in the Run circuit but not in the Start circuit of the compressor four (4) times in one compressor call.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
RESULT: The ICC detects current in the Run circuit but not in the Start circuit of the compressor four (4) times in one compressor call.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
CODE: 07 - Compressor Open Run Circuit.
RESULT: The ICC detects current in the Start circuit but not in the Run circuit of the compressor.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
RESULT: The ICC detects current in the Start circuit but not in the Run circuit of the compressor.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
CODE: L7 - Compressor Open Run Circuit.
RESULT: The ICC detects current in the Start circuit but not in the Run circuit of the compressor four (4) times in one compressor call.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
RESULT: The ICC detects current in the Start circuit but not in the Run circuit of the compressor four (4) times in one compressor call.
FIX: Check for damaged, miswired, or wrong run capacitor. Check for broken Wires, loose connectors, or miswired compressor. Check compressor windings for continuity.
CODE: 09 - Low Secondary Volts.
RESULT: The secondary voltage at R and C is below 18VAC.
FIX: Control transformer overloaded. Low line voltage.
RESULT: The secondary voltage at R and C is below 18VAC.
FIX: Control transformer overloaded. Low line voltage.
CODE: 21 - Low Pressure Control Open.
RESULT: The ICC detects the LPC is open. Note: The low pressure control is ignored for the first 90 seconds of compressor operation .
FIX: Unit has low refrigerant charge. Indoor coil is frozen (cooling mode). Dirty indoor coil or filter (cooling mode). Indoor blower is not running (cooling mode). Outdoor coil is frozen (heating mode). Expansion valve is not operating correctly.
RESULT: The ICC detects the LPC is open. Note: The low pressure control is ignored for the first 90 seconds of compressor operation .
FIX: Unit has low refrigerant charge. Indoor coil is frozen (cooling mode). Dirty indoor coil or filter (cooling mode). Indoor blower is not running (cooling mode). Outdoor coil is frozen (heating mode). Expansion valve is not operating correctly.
CODE: L21 Flashing.
RESULT: Active Protection, Low Pressure Control Trip.
FIX: LPC has opened 3 times in the same cooling operation, the ICC has locked out the compressor to protect it. ICC alternately flashes L and 21.
RESULT: Active Protection, Low Pressure Control Trip.
FIX: LPC has opened 3 times in the same cooling operation, the ICC has locked out the compressor to protect it. ICC alternately flashes L and 21.
CODE: 27.
RESULT: Low Line Voltage or No Line Voltage Fault.
FIX: Check incoming line voltage to the disconnect and unit. Check wiring connections.
RESULT: Low Line Voltage or No Line Voltage Fault.
FIX: Check incoming line voltage to the disconnect and unit. Check wiring connections.
CODE: 28.
RESULT: High Line Voltage Fault.
FIX: Check line voltage.
RESULT: High Line Voltage Fault.
FIX: Check line voltage.
CODE: 29.
RESULT: High Pressure Control Open. The ICC detects the HPC is open.
FIX: Outdoor coil is dirty (cooling mode). Outdoor fan is not running (cooling mode). Dirty indoor coil or filter (heating mode). Indoor blower is not running (heating mode). Liquid line restriction. Excessive refrigerant charge.
RESULT: High Pressure Control Open. The ICC detects the HPC is open.
FIX: Outdoor coil is dirty (cooling mode). Outdoor fan is not running (cooling mode). Dirty indoor coil or filter (heating mode). Indoor blower is not running (heating mode). Liquid line restriction. Excessive refrigerant charge.
CODE: L29 Flashing - Active Protection.
RESULT: High Pressure Control Trip.
FIX: LPC has opened 3 times in the same cooling operation, the ICC has locked out the compressor to protect it. ICC alternately flashes L and 29.
RESULT: High Pressure Control Trip.
FIX: LPC has opened 3 times in the same cooling operation, the ICC has locked out the compressor to protect it. ICC alternately flashes L and 29.
CODE: 30 - Fuse Open.
RESULT: The ICC detects the on-board fuse is open.
FIX: The 3 amp fuse on the ICC is open. Low voltage Wiring at R and C is damaged or miswired.
RESULT: The ICC detects the on-board fuse is open.
FIX: The 3 amp fuse on the ICC is open. Low voltage Wiring at R and C is damaged or miswired.
CODE: 80 - Low Air Flow.
RESULT: The ICC detects that the indoor unit is not providing the minimum airflow requirements.
FIX: Misappliedwrong indoor air mover - replace With properly sized unit.
RESULT: The ICC detects that the indoor unit is not providing the minimum airflow requirements.
FIX: Misappliedwrong indoor air mover - replace With properly sized unit.
CODE: 83 - Condenser Coil Temperature Fault.
RESULT: The sensor detects an abnormally low or high coil temperature.
FIX: Replace the sensor. Check sensor is installed correctly on control.
RESULT: The sensor detects an abnormally low or high coil temperature.
FIX: Replace the sensor. Check sensor is installed correctly on control.
CODE: 84 - Outdoor Ambient Temperature Fault.
RESULT: The sensor detects an abnormally low or high outdoor ambient temperature.
FIX: Check unit placement - If the outdoor unit is in a high temperature area, wait until the ambient temperature drops and check sensor reading. Replace the sensor. Check sensor is installed correctly on control.
RESULT: The sensor detects an abnormally low or high outdoor ambient temperature.
FIX: Check unit placement - If the outdoor unit is in a high temperature area, wait until the ambient temperature drops and check sensor reading. Replace the sensor. Check sensor is installed correctly on control.
CODE: 93 - Internal Control Fault.
RESULT: The control is not functioning properly.
FIX: Check control for proper system Operation. Replace control.
RESULT: The control is not functioning properly.
FIX: Check control for proper system Operation. Replace control.
CODE: d1.
RESULT: N0 Shared Data.
FIX: Replace memory card With correct system information.
RESULT: N0 Shared Data.
FIX: Replace memory card With correct system information.
CODE: d3 - Airflow CFM Mismatch.
RESULT: The indoor air mover (air handler/furnace) cannot supply the required airflow for proper system operation.
FIX: Misappliedwrong indoor air mover-replace With properly sized air handler/furnace.
RESULT: The indoor air mover (air handler/furnace) cannot supply the required airflow for proper system operation.
FIX: Misappliedwrong indoor air mover-replace With properly sized air handler/furnace.
CODE: d4 - (Device) Memory Card Invalid for Device.
RESULT: The data in the memory card inserted into the control board does not match the data in the control.
FIX: Check memory card to ensure it matches device. Check if memory card is present.
RESULT: The data in the memory card inserted into the control board does not match the data in the control.
FIX: Check memory card to ensure it matches device. Check if memory card is present.
CODE: d8 - Old Shared Data.
RESULT: System data is obsolete.
FIX: If system Will not operate, order new memory card to update system information.
RESULT: System data is obsolete.
FIX: If system Will not operate, order new memory card to update system information.
See What Our Customers Are Saying:
Nov 9, 2018
All staff concerned were total professionals. Sales rep Dave was like having an old friend at your house. No up selling or pressure, just good honest facts and figures. The owners and assistant who installed our unit worked quietly, efficiently and left our home clean. We could not have been happier with the service and attention we were given. We are so happy a family member recommended Twintech. She said "don't call anyone else, just call them...they are amazing". And they were!!! Thank you guys for the great work!!! A. Johnson
Oct 28, 2018
We are completing a large project adding an addition on to our house and couldnt be more pleased with our decision to trust Twintech with our hvac work. They removed and replaced the furnace, installed a new A/C unit, swapped our tank water heater for a tankless unit, and completed ducting and new A/C lines through the addition. Without hesitation we would recommend Twintech to anyone.
Sep 6, 2018
Honest, very personable , men of their word ,workmanship xcellent ,showed up when promised ,They do not try to up sell ,rather give good advice instead . Price was very fair in my opinion .We have a family member with a medical condition and I think they made us a priority .Very happy with these guys . (Nice guys ) Stu Leffler Ajax.
Sep 5, 2018
Very professional, courteous, knowledgeable staff. Sales staff (David Gergley) excellent in knowledge and getting the job setup and installation was very prompt. Greg and Peter (technicians) knew their stuff and stuck around after completion to make sure it all worked properly and that I understood how it all was installed and how the unit worked. Would highly recommend them! Thanks for a great job-house is now cool and comfortable.
Sep 4, 2018
I had Twintech install a brand new air condition back in June of this year and I'm very happy with their service. I have a very busy schedule so I sent out an email to 7 or 8 HVAC companies just to get an idea of what it would cost. Dave at Twintech and only one other company were able to give me an approximate quote through email. Many of the companies I reached out to didn't even respond. I decided to meet with Dave and he was very friendly and professional. He gave me a good quote for a name brand/energy efficient AC with installation from their certified technicians. It was an easy decision to go with them.
Within a week I had the unit installed and working perfectly. Their technicians were very helpful and answered all of my questions. I'll definitely be calling them back for all of my HVAC needs in the future.
Oct 9, 2018
The people from Twintech were very friendly and personable...from the salesman to the installers. The installation was done as scheduled. I love my new air conditioner. My neighbour has a York and that thing is so noisy compared to my Goodman!! Thanks Twintech!!
Sep 5, 2018
Thank you, Twintech. They installed an A/C in my home in the middle of a heat wave which we appreciated very much. I found the team good, not overly friendly, other than the brothers. Dave, the salesperson was awesome, and, it's because of him that I was sold on using Twintech. I had other questions about additional work I am curious about and would have liked them to follow up and provide a quote. Other than that, which ultimately is not related to the great work they did, I would definitely recommend them, although I don't believe they go outside of Durham (check with them).
Aug 4, 2018
We have used this company a few times so I can't remember exactly what we paid but I do know that their fees are always very reasonable.
The first time we called Greg was when our furnace conked out while we were away. He came right away, showed me the problem and fixed it immediately.
The second time was when we needed an air conditioner moved and lifted to a platform. Again, he showed up on time, completed the job quickly (including a new gas line) and the fee was very reasonable.
We have received a quote from Greg to replace the air conditioner and furnace and when we are ready to move ahead, we will be calling him.
I have no hesitation in recommending TwinTech!
Jul 19, 2018
Our rating for Twintech is 5/5 stars. They are very professional and efficient, and the transparency they maintain right from the preliminary assessment till the day of the work is a testament to their experience in the field. We had Twintech replace our air conditioning and furnace, and we appreciate the efforts taken by Greg.
Apr 30, 2018
After 18 years my Air conditioner died in the middle of a heat wave. I entered my information on Home Stars and within the hour Dave from Twin Tech responded and offered to meet me as soon as possible depending on my availability. Dave was very knowledgeable about the products Twin Tech offered and even though this was the first quote I received . I felt very comfortable in giving Twin Tech my business. maybe it was the professional approach. Needless to say that the crew with Greg and Grant arrived promptly at the time they committed to were very professional and within a few hours had the place cool. They cleaned up and one would never know that I had work done . I know that the System is new and I probably wont need to worry about it for some time. However with the professionalism displayed by the crew I feel assured that should I need to call for service Twin Tech will respond. I also know that should I need a new Heating system I will go with Twin Tech. Keep up the good work.
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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