KeepRite mini split error code E5

Common causes

• The indoor evaporator coil temperature (T2) thermistor has failed (they do drift and fail with age and heat cycling).
• Its plug has worked loose from the control board, or a pin has corroded.
• The sensor lead is chafed, pinched or chewed, giving an intermittent open or short.
• The control board's sensor input has failed (rare compared with the sensor itself).

How to fix it yourself

Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.

1. Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
2. If the code comes straight back after a reset, the fault is real and not a glitch.
3. With power off, locate the indoor evaporator coil temperature sensor (T2) pushed into a small copper well on the evaporator coil, reachable with the front panel and filters removed. Follow its lead back to the board and reseat the plug firmly.
4. Inspect the lead for damage along its whole length, especially where it passes through the chassis.
5. If you have a multimeter, unplug the sensor and measure its resistance. A reading near zero ohms (short) or infinite (open) confirms a bad sensor. Most mini split thermistors read roughly 5 to 20 kΩ at room temperature, so a value in that range with a steady drift as you warm it in your hand means the sensor is fine and the board is the suspect.
6. Replacement thermistors are inexpensive and plug in. Match the part number from the parts list for your model.

Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.

When to call a technician

Sensor swaps are a doable DIY job on most units. Call a technician if the sensor tests good and the code persists, because that points at the control board.

Common causes

• A dirty outdoor coil or failed outdoor fan.
• Low supply voltage (the unit draws more current to compensate).
• A refrigerant overcharge.
• A failing compressor.

How to fix it yourself

Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.

1. Look at the outdoor unit: clear leaves, cottonwood fluff, snow or ice from the coil and make sure the fan can spin freely and nothing is stacked against the cabinet.
2. If you own a multimeter and are comfortable using it, measure the supply voltage at the outdoor unit's L1 and L2 terminals with the unit running. A 230 V system should read roughly 208 to 253 VAC.
3. Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
4. Note whether it trips only in extreme heat.

Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.

When to call a technician

If the coil is clean and voltage is normal, a technician should check compressor current and the charge.