Friedrich Air Conditioner Error Code E5

E5 indicates the indoor ambient temperature probe has an open circuit and is not sending a readable signal to the control board. The control board responds by assuming a fixed indoor temperature of 90 degrees Fahrenheit and continuing to operate the unit. This failsafe allows the unit to keep running but without accurate temperature feedback, so cooling performance may be inconsistent. The probe should be tested with a multimeter and replaced if it does not return a readable resistance value.

The unit will continue to operate using the 90 degree default assumption, so it is not in an immediate safety shutdown. However, running without accurate temperature sensing means the unit may not cycle correctly, potentially leading to inefficient operation or short-cycling. It is best to address the fault promptly rather than running the unit indefinitely in this condition.

If only the indoor thermistor probe needs replacement, parts typically cost in the range of $15 to $50 depending on the specific model. If a technician is needed for diagnosis and replacement, total repair costs including labor generally fall in the range of $75 to $200. Control board replacement, if required, would increase costs significantly beyond that range.

A knowledgeable DIYer can diagnose E5 by disconnecting the indoor probe and measuring its resistance with a multimeter. If the probe reads infinite resistance or OL, it needs to be replaced. Reconnecting a loose connector is also a straightforward fix. If the wiring or control board is involved, those repairs may require more technical comfort with appliance wiring.

A power reset may temporarily clear the displayed code, but if the indoor probe is still open or disconnected, the E5 error will return once the control board attempts to read the sensor again. The underlying fault, whether a failed probe, loose connector, or damaged wire, must be corrected for the code to stay cleared.