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:
Jul 3, 2022
Great service and great people to deal with, from sales to installer. I highly recommend this company.
Apr 28, 2022
Twintech replaced our aging furnace and air conditioner recently. I highly recommend this company. Their quote was competitive, they were on time and respectful of our home and extremely professional. From the salesman to the installers and the owner who followed up afterward to ensure we were satisfied, we are very pleased with the service. We are looking forward to working with this company for all of our HVAC needs for the years to come. Excellent workmanship and service!
Apr 28, 2022
We wanted to get our AC replaced as it was 22-years old and added to this our furnace was costing more and more to repair. So, we decided to get both the furnace and AC replaced.
After going through a few quotes and product reviews we decided to go with Twintech. The three-men crew arrived early in the morning, wasted no time and got to work right away. By 2:00 pm, they were all done. Ive found their work to be top notch and they were completely professional. I had all my questions answered to my satisfaction both during the progress of their work and at end.
I have pleasure in recommending Twintech to anyone who is looking to get their furnace or Ac replaced
Nathan S.
Apr 28, 2022
Our air conditioner died On a Saturday and within hours Dave came out to take a look and discuss replacement/repair options.
The new air conditioner was installed on the Wednesday. The new unit was installed quickly. The installers were friendly and cleaned up afterwards.
We noticed a slight leak around the furnace that night and they came out the next day and fixed the issue. It has been working great and is quieter than our previous unit.
Very satisfied and would highly recommend TwinTech.
Apr 28, 2022
I contacted TwinTech to replace my 20-year old A/C. Dave, their service rep, promptly replied and was at my home within 2 hours. He was friendly and knowledgeable and didn't try to upgrade or oversell their A/C units but suggested the best fit for my small 1000 feet bungalow. Although this was during a heatwave and very busy, they were able to fit me in 2 days later. The TwinTech crew installed a 1.5 ton Ducane A/C unit that is now running smoothly while maintaining a constant cooling temperature. The crew were very courteous, professional and efficient and I will definitely recommend TwinTech to family and friends. I much appreciated your great service.
Nancy M., Oshawa
Apr 28, 2022
We had a great experience. The guys who installed our a/c did a nice job. Cleaned up.
Apr 28, 2022
excellent crew, fast and efficient! Would call them again when I need a new furnace.
Apr 28, 2022
Professional, courteous and efficient, dont need to say more than that! Use them you will not regret it.
Apr 28, 2022
TwinTech was a pleasure to deal with from the estimate through installation. We replaced a 28 year old a/c unit with one recommended by TwinTech's sales representative Dave who took the time to go over the product with us and answer any questions. The warranty is for 10 years parts and labour and they will complete the registration for you. Installation was by Greg (owner) and Mitch and Spencer who were quick and efficient and left everything clean and tidy.
Apr 28, 2022
Very professional, from the sales consultation and inspection to the final installation. Met every expectations we had for the job. A local business with great client support. We highly recommend. Twintech is a blue chip! Thanks!
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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