12 Common Problems With PTAC Units & How to Fix Them

While PTAC units are the best option for energy-efficient, cost-effective climate control, they are not exempted from problems you usually experience from other types of ACs. There are easy solutions to the problems in most cases, but you have to know what to look for.

Here are 10 common problems with PTAC units:

  1. PTAC unit not blowing hot/ cold air
  2. Unit not turning on
  3. Unit running continuously
  4. Unit making a humming or buzzing noise
  5. Inadequate pressure flowing in or out of the unit
  6. AC unit leaking water inside your room
  7. Push buttons not working correctly
  8. Tripping of circuit breaker
  9. Humidity and moisture problems
  10. Black mold coming from air vents
  11. Ice formation on the unit
  12. Temperature mismatch

A Humming Or Buzzing Noise

With the winter cold coming in strong, you decide to turn on your PTAC system, and after a few minutes, a humming or noise comes out, so you give it some time to stop. But, unfortunately, it doesn’t stop, and you start wondering what might be the problem with your unit.

The buzzing or humming noise could be due to damaged isolation feet, a malfunctioning compressor, or loose parts in your packaged terminal air conditioner. Either way, you probably may need to get a professional to get that fixed.

Opting to do it by yourself can be tricky since you are not quite conversant with how the inside part of PTAC units works.

PTAC Unit Not Blowing Hot/ Cold Air

Having to struggle with an air conditioning unit blowing cold air when you need to blow warm air and vice versa is pretty annoying. This problem could be due to the thermostat or the refrigerant levels.

If your PTAC unit has issues blowing hot air, you can look at your thermostat for proper operation. If you notice anything unusual with your PTAC unit, you can contact a professional to look at your PTAC system and help you repair any shorted wires.

This may be due to low refrigerant levels for problems associated with the cooling issues. If that’s the case, make sure to remove any blockages in the coolant lines. Also, be sure to clean your PTAC filters and coils.

Unit Not Turning On

Aside from making sure your air conditioning is plugged in, you probably would want to look at the power cords for shorts. You also want to ensure that the connection is not interrupted by lousy wiring or breakage.

You could try testing the voltage of the power cord to ensure the voltage is enough to support the PTAC system. Make sure to check for any blown fuses.

System Operating Pressures

Another common problem is inadequate pressure flowing in or out of the unit, causing operational issues. You may notice that your packaged terminal air conditioner suction or discharge pressures are lower than usual.

This is usually caused by insufficient refrigerant or the blocked coolant lines, or the lines need to be replaced. When the operating pressures of the PTAC units are high, this may be due to bad wiring with the fan motor or a bad compressor.

So make sure to check the blower fans’ compressor and ensure the coils and the air filter are clean.

Humidity And Moisture Problems

If you notice moisture in any of your PTAC units, this could result from a few things, such as leaks. Moisture leads to the accumulation of mold or mildew around the vents. High humidity in your air conditioner is often caused by the PTAC unit’s evaporator not being able to dehumidify as it’s supposed to.

If the evaporator coils are frozen, they won’t cool and dehumidify the air. To avoid the accumulation of molds due to moisture problems, always ensure you do regular maintenance and clean your PTAC units as often as possible.

Tripping Of The Circuit Breaker

So you’ve noticed your PTAC unit circuit breaker is tripping, but you are clueless about what’s happening to your air conditioner?

PTAC units will always trip the circuit breaker if they pull in more amps than the breaker is rated for. I mean that if you have a 20-amp breaker and the PTAC unit pulls 30amps, the breaker will trip. The trips happen to protect you from overcurrents that may damage your unit and cause fires.

Other causes of your PTAC system tripping the circuit breaker are;

  • Dirty outside unit
  • The compressor has trouble starting
  • motor has shorted
  • The compressor is grounded
  • Dirty air filter

With all these causes, an air conditioner technician can help you resolve the problem.

Formation of Ice

When airflow from the PTAC units to the room is restricted, then the exchange of thermal energy between the PTAC unit and the room is restricted. As a result, most of the cooling air stays around the evaporator coil, causing the temperature around them to fall.

This, in return, causes the formation of ice which gradually continues to form, causing the PTAC unit to freeze up. You can stop the formation of ice and your PTAC unit from freezing up by either;

  • Letting your PTAC unit defrost
  • Changing your filter if it’s dirty
  • Opening all the closed supply vents in your room
  • Make sure no drapes or furniture are blocking the return vents.

How To Troubleshoot PTAC Units

Thanks to the self-diagnostic test that most, but not all, Packaged Terminal Air Conditioners have, you can troubleshoot your PTAC units without the need for any technical skills or tools. All you need to do is activate the self-diagnosis feature whenever you want to know whether your PTAC unit is working correctly.

But the critical step to troubleshoot your PTAC system is resetting the system, and if the problem is not fully resolved, you can use the self-diagnostic tool.

Once you put the air conditioner on diagnostic mode, it automatically scans for errors and displays a unique code. It’s safe to say that you can determine if a manual reset will get your air conditioner working by using an error code as a pointer.

Your PTAC unit will undoubtedly come with a manual that will give you a step-by-step guide to running the self-diagnostic feature.

Once you follow these steps correctly, your PTAC system will be activated, and all you have to do is give it a few more minutes to run the diagnostic test. An error code will appear on the display screen upon completion.

If no error code is displayed, then that means your air conditioning system is unable to detect the error.

When should a PTAC Unit be Replaced?

Are you unsure whether your PTAC unit needs to be replaced on not? Well, here are a few signs that it’s time to replace your unit.

If the PTAC Unit is not as Efficient as Before

You will know when your PTAC system is not as efficient as how it was when you bought it, and that’s the perfect excuse for you t start considering a new PTAC unit. You can determine whether your packaged terminal air conditioner needs to be replaced by taking a look at the Energy Efficiency Ratio (EER rating).

The EER rating measures how efficiently the unit converts electricity into output energy. New PTAC units’ EER rating will hover around 5.0, but old PTAC units will drop to 3.0. This is enough to let you know that you need to start saving up for a new PTAC unit.

If the Unit is not EPA Compliant

Most PTAC units do well by EPA standards. Still, for the ancient PTAC units that have not been maintained with environmentally friendly coolants, there’s a possibility you are in danger of no longer being compliant with the environment. This means it’s high time you replace your PTAC unit with one that is environmentally friendly.

If the PTAC System makes Excessive Noise

Most old PTAC units are extremely noisy, making it uncomfortable for you to stay in a room with noise. A noisy PTAC system will undoubtedly be a disadvantage, especially if you have installed PTAC units in your hotel or motels. No guest would want to be in such a noisy room.

If your PTAC unit is producing excessive noise, then it’s time you replace it with a less quiet one.

Complete Guide To Ptac Error Codes 

Like any other air conditioner, PTAC units will also encounter maintenance issues. Typically, there are four categories of error codes that PTAC systems will display for a maintenance issue. They include;

System Modes

There are system modes designed into your PTAC for security, compatibility, or safety functions, and each of these will display an error code. These error codes may not be maintenance issues, but they can be the cause of your system not functioning.

System modes can be fixed by changing the settings or improving the PTAC’s surroundings. Some of the system code error codes include;

FD- Front Desk Switch

 The code FD means that your system’s front desk switch is closed. This means that all other outputs for the PTAC unit are off. To correct this, you may need to ask the front desk to reopen the switch so that your system can resume its regular operation.

EH-Emergency Hydronic Mode

When your unit displays the EH, the compressor is off, and the EHH switch is closed. To resolve this, you will be required to reopen the emergency hydronic switch.

FP- Freeze Protection

This error code means that your PTAC is in freeze protection mode, activated when the thermostat detects temperatures below 40 degrees Fahrenheit. This is activated to keep the essential elements of your unit from freezing and causing any damage.

Once the thermostat reads above 43 degrees Fahrenheit, your system will deactivate the FP code.

UR- Un-Rented Mode

This error code shows that the unit has a status of UN-Rented, which may keep the PTAC unit from functioning as expected. To move the PTAC from this mode, you must contact the front desk to change the status to Rented.

ON- Wired Thermostat Configuration

The ON code on PTAC units indicates that the unit has been configured to work with a wired thermostat rather than a wireless one. So, if you are trying to use the PTAC unit with a wireless thermostat, this may cause a configuration error. You can fix this by changing the configuration mode to the proper setting in the configuration menu.

Failure Codes

Failure codes mean that a piece of the PTAC unit has stopped working properly or has failed. To fix these sorts of codes, you will need to replace the defective piece or repair it if need be. They include;

FThermistor And Thermostat Failure

This code typically displays a double failure. It means that the Indoor Ambient Thermistor is reading outside of the predetermined range. The code also means that the wireless thermostat is no longer sending signals to the unit control.

The only way to fix this is by replacing the black thermistor or the wireless thermistor.

Wireless Remote Thermostat Failure

This error code displays that the wireless remote thermostat has automatically failed, and you will be required to replace it.

Indoor Ambient Thermistor (Black) Failure

Like the F1, the F3 code shows that the black Indoor Ambient Thermistor on the PTAC reads outside of the predetermined range of between 20 degrees to 200 degrees. The only way to solve this is by replacing the thermistor.

F4- Indoor Coil Thermistor (Red) Failure

This error code means that the red indoor coil thermistor is not working or has exceeded its operating tolerance, and you will also need to replace it.

F5- Wireless Thermostat Failure

This code in PTAC units displays that the wireless thermostat has failed, and to fix it, you will either need to replace it or rebind the thermostat.

F6- Indoor Discharge Thermistor (Yellow) Failure

This indicates a failure in the yellow Indoor Discharge Thermistor and means it’s either above or below its operating tolerance; thus, the battery needs to be replaced.

FB- Low Remote Battery

When any of your PTAC Units displays these error codes, it simply means that the battery in the PTAC remote is very low, and you may need to replace the battery.

H1- High Voltage Protection

This code indicates that the input voltage is high, and as a solution, you will need to check the voltage coming into the PTAC unit and adjust it accordingly.

Airflow Alerts

These codes show various airflow systems and temperature problems and require general maintenance on parts such as the coil and the filter. The codes include:

L6- Discharge Air Heat Warning

This code in PTAC units indicates that the air flowing out of the PTAC is scorching for regular operation and can only be fixed by cleaning the filter.

LC-Outdoor Coil Thermistor (Red) Heat Warming

This code will be displayed when the red outdoor coil thermistor reaches temperatures too hot than the average temperature. The only way this can be fixed is by cleaning the condenser coils and the filter.

C2-Indoor Air Recirculation

This means that the air inside your room is being recirculated through the PTAC, which creates a problem with both the air conditioning and the freshness in the room. You can fix this by looking at the seal around your PTAC. Make sure it creates a solid barrier between the inside and outside air.

C2-Outdoor Coil Heat Warning

These PTAC units error codes display that the temperature of the outdoor coils is exceptionally high for outdoor ambient readings. You can fix this is by cleaning the coils and removing anything blocking the outside air from flowing in.

Refrigeration Errors

PTAC units also have issues related to the refrigeration system and cooling temperatures. While these error codes may be simple to solve, they may also require a professional to resolve them. They include;

C1, C3, and C4- Indoor Coil Freeze Warning

If your PTAC shows any of these error codes, the indoor coil is freezing or has already frozen. To resolve this, you will need to clean up the filter and check for any defects in the blowers and fans.

Be sure to also look for any possible leaks and ensure the capillary tube is not restricted in any way.

C6-Poor Unit Performance

This PTAC Units error code shows that multiple unit parts are not running as expected or are malfunctioning. To fix this, you will need to check the operation of the blower motor, electric heat components, and compressor.

C7- Indoor Freezing Lockout

The C7 code displays the same freezing issues from C1, C3, and C4 error codes. In addition, this code will lock the temperature settings and other normal controls for up to ten minutes. You will need to follow the troubleshooting steps for the Indoor Coil Freeze warning to fix this.

Wrapping Up

Now you are in the know. So next time you notice something unusual with your Packaged Therminal Air Conditioning, you certainly will know what caused it and how you can fix the problem.

If you cannot do it yourself, please feel free to contact us for any help. We will certainly help you make replacements, repair, and maintain your PTAC unit.