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:
Jan 1, 2015
Really nice honest guys. It was a pleasure to do business with a company that does exactly what they say theyre going to do! My basement was cleaner after they installed my new furnace and AC. Thanks again Greg and Grant and for doing such a great job.
Jan 1, 2015
5 star service!! I had twin tech install a high efficiency furnace and hot water tank at my home. I am taking time to write this review as a thanks for what I viewed as next level service that went above and beyond. Prior to installation they explained my specific options without pushy sales tactics and up front costs. Greg and Grant replaced a large portion of the duct work (built in their own shop) that had rusted over the years which resulted in a great looking job. It was a pleasure to work with people are passionate and take pride in their work. Following the installation they explained all aspects and maintenance of the new equipment. Products have worked flawlessly. Thanks again Greg and Grant! Highly recommend!!
Jan 1, 2015
Twin Tech was great; they were honest, reliable and very thorough. I would recommend their services and will definitely be using them in the future.
Jan 1, 2015
Hi Dave, Thank You Dave for coming to my aid this past summer when my AC quit. Your men did a great job installing and cleaning the area. The unit is working very well and i would highly recommend your company TwinTech. Dave you delivered what you sold and i truly appreciate it.
Jan 1, 2015
My experience with TWINTECH has been excellent, start to finish. While doing market research I made a list of several local companies and called them for some high-level information. Dave was the first to call me back, and the only one to book a meeting to see my place in order to give an informed, accurate estimate. He reviewed the different AC makes and models with me, explained the technology, and made a recommendation appropriate to my home. The installation went smoothly. I had one post-installation issue there was moderate noise/vibrations coming from the duct system. I called about this, booked an appointment, and the technician resolved the issue during the service call. I feel assured having a 10-year warranty on parts & labour. I would recommend TWINTECH to anyone considering an AC or furnace for their home. Regards,
Jan 1, 2015
Thank you for your attention to detail regarding my purchase of a new air conditioner. Twintech arrived at the appointed time and were totally professional on the installation process completing the job quickly. PS thanks for the assistance applying for the government rebate
Jan 1, 2015
Dave and the guys from Twintech did a great job of installing my AC. They came on time did a nice neat job and cleaned up after themselves! Do not waste your time call Twintech first.
Jan 1, 2015
My AC unit was not working at all and our furnace that was still working but not giving us any trouble was over 15 years old. So I had 3 heating companies come out to give us a quote on replacing both the AC and the furnace at the same time. Two companies right away recommended that I replace both units simply because they were old. Dave from twintech however suggested that we save some money and replace the AC only because it seemed to him that the furnace was still in great shape and was running fine. He told us that he would have his technicians inspect the furnace thoroughly when they had it apart to install the AC. My husband was at home when the furnace was apart and was very impressed when the tech took him downstairs to personally show him that the furnace was in excellent working condition. He also cleaned the furnace at no extra charge. So now I have an honest heating and AC company that I can highly recommend to other home owners. Great job Thank You!
Jan 1, 2015
I had made the decision to replace my furnace and AC earlier this year. After meeting with several HVAC contractors I decided to go with Dave and his company. Dave was on time, polite, friendly and very professional. He took the time to answer all my questions and to explain the scope of work that would be required to do the job. The technicians arrived on time did a professional installation and completed the job on schedule. They respected my home by putting down vinyl runners to protect my floors and did a very thorough clean up. Im very pleased with my decision to go with Dave and his team. I would highly recommend them to anyone who is considering upgrading their furnace and air conditioner.
Jan 1, 2015
I have no problem in recommending Dave and the TWINTECH team to any home owner who is looking for quality heating and AC products and expert service.
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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