American Standard Heat Pump Error Codes – Troubleshooting Guide

American Standard offers a wide range of heat pumps. Some of the models can save you up to 56% on energy bills; moreover, all the units should last for around 15 years.

You might already know that winter is the toughest period for any heat pump and American Standard units are no exception.

Below you’ll find the error codes that you may see on your heat pump. Of course, the majority of them have to do with the defrost cycles.

American Standard Heat Pump Error Codes

1 Flash

The ambient temperature sensor is out of range (open or shorted).

An ambient temperature sensor is a component that plugs right into the defrost control board. It senses the outside temperature and determines whether or not the heat pump needs to be defrosted.

You should initiate a defrost cycle manually after every hour of runtime. The defrost cycle should last for around 15 minutes.

Simply turn on the mode manually.

During the defrost cycle, the heat pump switches the outdoor fan off and turns the evaporator into a condenser. The high-pressure refrigerant gets warmed up and then melts the ice while circulating through the coil.

Tip: many heat pumps will run the defrost cycle automatically, but if you feel like the ‘procedure’ is too short, don’t be afraid to run the cycle manually.

Remember that it’s absolutely okay for the heat pump to develop light frost. As long as you keep an eye on the defrosting cycles, everything should be fine.

Read: Who Makes The Best Heat Pump System And Why?

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2 Flashes

The coil temperature sensor is out of range (open or shorted).

Once again, you would have to initiate a 15-minute defrost cycle every hour of runtime.

A serious problem can occur if your heat pump freezes up for more than 4 hours.

The job of the coil temperature sensor is to tell the system when the coil gets frosted over. However, if there is something wrong with the sensor, the unit will not automatically initiate a defrost cycle. 

Here are a few other tricks (apart from manually initiating the defrost cycle) that you can try doing to get rid of the ice on your heat pump:

Read: What Temperature Is A Heat Pump Not Effective?

  • Run the fan

If your system is equipped with a fan, then you can try turning it on for around 60 minutes.

This is a short-term solution that you can give a go. In case the temperature is extremely low, you might want to set the fan on an exhaust setting.

  • Move the sensor

The temperature sensor is located on the exterior of the heat pump. If it is located on the part of the unit that is warmer than the rest of the heat pump or if the component is in direct sunlight, then the sensor might not tell the system to initiate a defrost cycle.

You can move the sensor to the outside part of the unit, but do bear in mind that such a solution can only be used as a last resort as you can end up damaging the sensor.

3 Flashes

The low-pressure switch is open.

It is important to understand that the pressures in the unit should always stay within a certain range, in order for the heat pump to be able to function.

A low-pressure switch is a safety device that is usually located close to the compressor. If the refrigerant level is too low, the switch is going to shut off the compressor.

Read: Why Heat Pump Compressor Not Turning On?

Some things that might cause the low-pressure switch to open include: 

  • A low level of refrigerant
  • A clog in the liquid line part of the system (the strainer, distributor tubes, filter drier, or metering device)
  • A defective evaporator fan
  • A defective pump on the evaporator side

4 Flashes

A hard lockout has taken place.

Occurs after the fourth trip of LPCO.

When your heat pump locks out on the low-pressure switch, the problem might be with:

  • A low airflow across the evaporatorSome parts of the system might be dirty (like the filters or the evaporator coil, for example).
  • A high side restriction
  • A very light load that causes low pressure

Calling a professional to deal with this issue might be the best decision.

5 Flashes

A soft lockout has taken place.

If a hard lockout occurs only after the fourth trip of the LPCO, a soft lockout will take place:

  1. After the first low-pressure cut-out trip (for 15 minutes)
  2. After the second LPCO trip (for 30 minutes)
  3. In cooling mode, after the third low-pressure cut-out trip (for one hour)
  4. In heating mode, after the third LPCO trip (for 18 hours; will clear, if the outdoor thermostat rises above 40 F for at least half an hour)

6 Flashes

The defrost cycles are too close together.

Here are the factors that affect the frequency of the defrost cycle:

  • The heating load
  • The outdoor temperature
  • The outdoor humidity (the more humid it is, the more ice will form on the unit)

As we have already mentioned, it is absolutely normal for a heat pump to initiate a defrost cycle. But if that happens more often than every 30 minutes, then something is definitely wrong.

  1. Your unit might be undersized and unable to provide the proper amount of heat.
  2. The airflow through the outdoor unit might be blocked by debris, leaves, or snow.
  3. The air filters can be clogged or the coil in the indoor air handler is dirty – all these things affect the airflow.
  4. One of the sensors might have gone bad.
  5. A low level of refrigerant or a refrigerant leak can also be to blame.
  6. Finally, the fan motor, outdoor coil, or control board might be faulty.

Read: What Are Heat Pump Disadvantages?

7 Flashes

In timed defrost mode.

You would have to check the ambient sensor – it has to be in place and functioning.

Another component that you would have to inspect is the changeover (reversing) valve. This is the device that reverses the flow of the refrigerant in the system. 

  • The valve might be stuck.

The first thing that you can do is tap something on the actual valve. If there is dust or dirt, it should fall off.

Make sure that the pipes are not blocked or dirty and inspect the valve’s body – it shouldn’t have any holes or any other types of damage.

  • The valve might not be getting any power.

You would have to use a voltmeter to check if the valve is getting any power. By the way, the solenoid coil that is responsible for energizing the valve should also be receiving power.

You can also check if all the nearby wires are connected.

  • There might also be a refrigerant leak.

Warning! If you have never worked with wires or don’t feel comfortable doing that, then make sure to call a professional. 

8 Flashes

In timed defrost mode.

Check the coil sensor and the changeover valve.

However, the chances are high that the heat pump is simply not able to cope with the outside temperatures. Such an error occurs when the temperature outside falls below -7 F.

In a lot of cases, the unit will be able to resume operation only once the temperature rises to around 3 F.

Heat pumps become especially vulnerable when the snow starts to fall – the moisture will immediately freeze on the outdoor coil and a lot of snow will get drawn into the coil.

If there is snow falling or the temperatures are too low, you can try switching to ‘emergency heat’. This mode will help you get through the snowfall or a freezing evening, but it shouldn’t be turned on for too long.

9 Flashes

A low ambient soft lockout has taken place. 

Once again, it looks like the temperature had dropped below -7 F. Your American Standard heat pump will start operating again as soon as the temperature rises to at least 3 F (the operation will resume after a 15-minute soft lockout).

The majority of these errors are not exactly problems, there are just system notifications that are there to show you that a defrost cycle had started, for example.

You should be able to give your heat pump some time – the chances are high that the defrosting system has no issues and simply needs a couple of hours to sort the problem out. 

Tip: if your heat pump is not running during wintertime, give it around 3-4 hours so that it can defrost itself.

If the problem persists, only then you can start troubleshooting the unit.

Read: What Is Heat Pump? Everything You Need To Know