Rheem Air Conditioner Problems And Troubleshooting Guide

Perhaps the worst thing that could happen on a hot summer day is realizing that your Rheem system is not functioning normally. If that is not enough, not knowing what the problem ought to be could be devastating. However, this article will come in handy in helping you understand what might be the problem with your AC.

Rheem Air Conditioner Problems And Solutions

Below are some of the problems associated with Rheem air conditioners.

1. Rheem Air Conditioner not Cooling

Your central AC unit not blowing cold air when it’s running could be due to several reasons such as;

  1. Dirty or clogged filter- The Rheem unit could be experiencing clogged filters that hinder airflow into the AC, thus reducing the air conditioner’s cooling capacity.
  2. Dirty coils- A dirty condenser coil will always cause your AC system to have trouble blowing in cold air. Condenser coils are like a radiator that dissipates heat, but this can be impossible with dirty coils.
  3. Insufficient coolant- The coolant circulates through the evaporator coils, cooling the air flowing over it. So when there are inadequate coolant levels, your Rheem unit will fail to cool.
  4. Defective parts- If there are other faulty components such as a defective run capacitor, defective contactor, choked capillary, bad thermistor, faulty motor, or defective control board.


Always clean the air filters as frequently as possible, and you should replace them from time to time. Dirty coils also need to be cleaned frequently and in case of any defective parts, be sure to contact an HVAC service company to look into the matter.

2. Rheem Air Conditioner Turns On and Off

If the Rheem brand keeps turning on and off when turned on, you should not ignore it. Some of the reasons behind the short-cycling include;

  1. Thermostat location- If your thermostat is in an impractical spot, then the chances of your Rheem equipment short cycling are pretty high. What you may not know is that the thermostat sends on and off signals based on the surrounding temperatures, and that is why you cannot have it located near a warm sunny window or air supply vent, as it will cause the system to turn on and off.
  2. The cooling system is huge- The size of an air conditioner matters as you cannot have an oversized air conditioner in a small room and vice versa. Why? With an oversized air conditioner in a small house, the AC unit will cool the home quickly, thus shutting off shortly and turning on back. If you ignore it, you are likely to receive high energy bills and chances of a breakdown.


Be sure to contact an HVAC technician to help you choose the best suitable area to locate your thermostat and advise you on the size of the AC that best suits your home.

3. Rheem Air Conditioner not Turning On

The compressor to your Rheem heat pump could not turn on due to;

  1. Thermostat malfunction- A thermostat malfunction will considerably impact our air conditioner’s performance. You could start by checking the batteries to your thermostat as, at times, battery issues could be the reason behind the malfunction. Your thermostat’s display could be off; thus cannot signal your air conditioner to turn on.
  2. Low refrigerant- In most cases, low refrigerant could result from a refrigerant leak as cracks could have built up over time in the AC unit coil, thus the leakage.
  3. Defective capacitor- A capacitor is connected to the motor’s circuit and gives the motor an initial push to start running and disconnects once the motor reaches a specific speed. If your air conditioning unit is working harder, then the chances of you having a defective capacitor are very high. If you have issues with the capacitor, your AC compressor will not turn on.


If your thermostat uses batteries, check and replace batteries to avoid your compressor not turning on since refrigerant levels must match those of the manufacturer. It will be best if you contact an HVAC guy to help you. If you notice the capacitor is defective, be sure to replace it as soon as possible.

4. Rheem Outside Unit not Coming On

Is your outside unit not running? This could be issued with the circuit breaker, which is generally caused by a power surge, hence powering your AC system. Your outside unit not coming on could also result from a shut-off switch.


Check for a tripped circuit breaker and replace it if necessary also, make sure to turn on the shut-off switch if you realize it was off.

5. Rheem Air Conditioner Coil Problems

In most cases, coil problems are due to clogged or dirty coils. Dirty coils will always cause issues and cause your air conditioning unit to have trouble functioning as required.

Other coil problems include evaporator coil leaks or frozen evaporator coils. Freezing evaporator coils result from ice formation, while the leaking issues are due to clogged coils or rusted condensation pan.


Regular maintenance of the coils by keeping them clean will help prolong your system’s longevity. In addition, ensure proper and frequent replacement of the coils to prevent pressure on your unit.

6. Rheem Air Conditioner Blowing Hot Air

An AC unit blowing hot air is due to some problems, and they include;

  1. Low refrigerant levels- Low refrigerant levels due to a refrigerant leak. When the air conditioner is low on refrigerant, your unit will not be able to transfer as much heat out of your room, and this means the air coming from your air conditioner vents will be warmer than usual.
  2. Tripped Breaker
  3. Rheem AC units have two breakers, one in the outdoor unit and another in the indoor unit. So when the outside unit’s breaker trips, the inside unit continues to blow air in your room, but it won’t be cool air.


You can schedule a professional AC repair if you find your AC unit with low refrigerant levels. For the circuit breaker, you could try resetting it, and if it does not work, be sure to contact a professional from a reputable HVAC company.

7. Rheem Air Handler Fan Problems

If you realize your air conditioner’s blower fan is not working, this could be an issue with a defective thermostat, banned out blower motor, bad control board, or a spoilt selector switch.


Contact an HVAC technician to help you fix any issue causing your air conditioner’s fan to have problems.

8. Rheem Air Conditioner Noisy or Loud

Rheem units are designed to stay quiet whenever they operate, but if you hear your air conditioner being noisy, there must be something with your HVAC system. Your AC system can produce loud sounds like buzzing, humming, grating, or squealing.

A noisy or loud noise coming out from the system could be due to a malfunctioning compressor or loose parts in your packaged terminal air conditioner.


Be sure to check the fan and replace it if it seems damaged. Be sure also to check the blades for any loose placement. Either way, you still need to contact a technician for an air conditioner service.

9. Rheem Air Conditioner Leaking Water

If your HVAC unit is leaking water in your home, this could be due to a clogged condensate drain line. Condensate drain lines do get clogged with dirt over time with debris, dirt, or dust.

So when the condensate drain line is clogged, water cannot escape the drain to the outside home.

A dirty air filter will also be the reason behind the leaking water and low refrigerant levels.


Be sure to clean and eliminate any debris or dirt you notice accumulated in the condensate drain line. Ensure the air filters are also clean or replaced to solve the issue.

Troubleshooting Tips to Try before Calling for AC Service

At times your Rheem HVAC unit could be in good condition, but a few fundamental issues could be the reason behind the unit not working. Below are some of the simple things you can check by yourself.

Check the Power to the Unit

Ensure that the outdoor and the indoor units’ power switches are on. Power switches sometimes get flipped inadvertently, making your unit not turn on.

Check the Power to the House and the Circuit Breaker

Make sure that power is reaching your house and the outlet used by your Rheem unit. Check the circuit breaker also and if it trips continuously. This could be a sign of a bigger problem.

Make Sure the Thermostat is Ready

If you plan to cool the room, make sure that the thermostat is in the cooling setting. If you want to warm your room, make sure the thermostat setting is in a warm setting.

If the settings are incorrect, you will have problems with your Rheem system. You could also check the thermostat batteries and make sure they are working.

Check the Air Filter and Vents

Ensure no debris or dirt has accumulated and clogged the air filters, as clogged filters will always cause problems with your AC unit. Clear them up if you see any debris or dirt in your air conditioner filters.

Also, check the vents and make sure they are open and nothing is blocking them.

Is There a Reset Button On a Rheem Air Conditioner and How to Use It

Rheem air conditioners have a reset button found mainly at the back of the HVAC unit. In most cases, during a power outage, your system may not start right away as expected once the power comes back, and you will have to reset the AC for it to operate once more. So how do you go about it?

Step 1- Chane the thermostat setting and raise the temperatures to 80 degrees Fahrenheit, preventing your system from turning on while resetting the compressor.

Step 2- Try to find the red rubber boot which covers the rest button on the back of the AC system case. You will find the reset button near the copper lines.

Step 3- Press the reset button and set your desired temperature with one finger. This way, it usually resets your Rheem system. But in case this fails to work, be sure to call a technician to offer an air conditioner service to your system.

Rheem Air Conditioner Error Codes

There are various error codes that you need to watch out for various error codes when your system is having problems. Below are some of the different error codes displayed from time to time.

Code 0- The unit is on standby and operating as expected.

Code D1-There’s no shared data. Here, you will need to replace the memory card with the correct system information.

Code D3- This code means an airflow mismatch, and the only way to fix this is by replacing the air handler with an appropriately sized one.

Code D4- Invalid memory card in the control board. To fix this, check whether the memory card is present and ensure it matches your device.

Code D8- It means that the old shared data system is obsolete. A new memory card will be required to update system information to fix it.

Code P- This error code means no current going to the compressor. You can fix this by checking if the motor protector is open or disconnected line voltage.

Code 1- The compressor runs continuously due to low refrigerant levels, a dirty air filter, or a dirty evap coil.

Code 2, 29, and Flashing L29- This error code means a high-pressure problem. Fixing this will require checking if the outdoor coils are dirty, the outdoor condenser fan motor is running, and if there’s a liquid line restriction.

Code 03- The system is short cycling, and the only way to fix this is by checking the thermostat wire connections and thermostat location in the zone.

Code o5,06,07, L6, and L7- The compressor has a problem due to an open circuit. To fix this, check for damaged or miswired run capacitors, loose connectors, broken wires, or a miswired compressor.


Whether you are using a brand new unit or an old one, understanding your AC system is quite essential as this helps avoid the mentioned problems. You can prevent most AC problems easily without calling Rheem technicians for a service call.

So, next time your AC gets a problem, I believe you will now have an idea of what might be the problem with your unit.