Room temperature thermistor error - Fujitsu ASU12RLS2 Wall Mounted Indoor Unit Air Handler 12,000 BTU 1

Error Code E71 - Outlet Control Thermistor open circuit -- Outlet Control Thermistor or wiring defective.

Check resistance of Outlet Control Thermistor, and check wiring for open circuit. Resistance should be between 4.9K Ohm and 6.2K Ohm at room temperature (68-77° F or 20-25° C). Replace Outlet Control Thermistor and/or wiring and retest.

Consult video below for instructions

https://youtu.be/hcKHCzuDvMQ

error code indicates that the electronic control board detects an open thermistor (temperature sensor). This is usually caused by a failed thermistor. It can also be caused by a wiring problem or a failed control board.

To troubleshoot this problem, follow these steps:

Unplug the dryer to completely disconnect electrical power. Shut off the gas supply.

Remove the bottom front service panel as shown in the first image below.

Locate the thermistor on the blower housing. The second image below shows the thermistor. It should have a red/white and a black wire attached to it. Pull at least one wire off and measure the resistance across the leads of the thermistor using a volt/ohm meter. You should measure about 10K ohms (10,000 ohms) of resistance at room temperature. If you measure infinite resistance or get much different reading, then the thermistor will need to be replaced. Even if the thermistor reads the correct resistance at room temperature, it could still be defective and giving a bad resistance reading at higher temperatures.

If you suspect that the thermistor is good, check the wiring connection at the main control board (black and red/black wires on the P2 connector). The procedure for accessing the control board is shown in the third image below. With the dryer still unplugged, pull the P2 connector (see diagram of board) and check the resistance through the black and red/white wires. NOTE: The wires down below at the thermistor must be properly attached back onto the thermistor to properly check this circuit. If you get a much higher resistance (or infinite resitance indicating an open circuit) when measuring this circuit from the wires at the control board, then you could have a wiring failure that is causing your problem. If the resistance is the same, I recommend replacing the thermistor and testing the dryer to see if it operates properly.

If you still get the error code after changing the thermistor, then the control board will need to be replaced.

Google says:
E6 Room temperature or evaporator temperature sensor open or short circuit
The prescribed cure:
Check to make sure the room temperature sensor is connected and reads the correct resistance value. If the sensor operates correctly, replace the control board.

This unit most likely employs a NTC thermistor as a thermometer sensor. Common resistance values are 1k ohms and 10k ohms at room temperature. As the temperature goes up, the sensor decreases in resistance.


The sensing element could look like any of the above, but with portable comfort units, they usually look like the bottom row of encapsulated and cabled assemblies.

The E1 code is an error code that appears on the LED temperature display of some digital air conditioners. The error code could mean anything from dirty air filters to a damaged room thermistor, a safety connected to your thermostat that detects room temperature. Troubleshooting the cause of this error code may improve your air conditioner's performance

Thermistors are inexpensive, easily-obtainable temperature sensors. They are easy to use and adaptable. Circuits with thermistors can have reasonable outout voltages - not the millivolt outputs thermocouples have. Because of these qualities, thermistors are widely used for simple temperature measurements. They're not used for high temperatures, but in the temperature ranges where they work they are widely used. Thermistors are temperature sensitive resistors. All resistors vary with temperature, but thermistors are constructed of semiconductor material with a resistivity that is especially sensitive to temperature. However, unlike most other resistive devices, the resistance of a thermistor decreases with increasing temperature. That's due to the properties of the semiconductor material that the thermistor is made from. For some, that may be counterintuitive, but it is correct. Here is a graph of resistance as a function of temperature for a typical thermistor. Notice how the resistance drops from 100 kW, to a very small value in a range around room temperature. Not only is the resistance change in the opposite direction from what you expect, but the magnitude of the percentage resistance change is substantial.

If you do not know the problem it may be cheaper to get a professional person to check it out.

If the display reads "F1" or "F2", a sensor has failed. Contact your Authorized Frigidaire Service Center.

That is actually a Ts error.

Thermistor Short Sensed

The Thermistor resistance is very low.
Check for:
- Clogged lint screen.
- Restricted vent system.
- Check Thermistor resistance.

Thermistor is Item #27 HERE


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Faulty tube sensor.

F1 is room temperarure sensor error. F2 is tube temperature sensor error.

The room sensor usually is located in the front of the condenser. The tube sensor is usually plugged in a tube near the condensor.

The tube temperature sensor (thermistor) should be about 10K ohms.