How to Replace an AC Evaporator Sensor

An air conditioning pressure evaporator sensor changes its internal resistance in relation to evaporator temperature. This information is used by the electronic control unit (ECU) for compressor control.

By cycling the compressor clutch on and off in response to evaporator temperature, the ECU prevents the evaporator from freezing up. This keeps the A/C system functioning properly and prevents damage.

Part 1 of 3: Locate the evaporator sensor

In order to safely and efficiently replace your evaporator sensor you need a couple of basic tools:

locating the evaporator sensor

Step 1: Locate the evaporator sensor. The evaporator sensor will either be mounted to the evaporator or the evaporator case.

The exact location of the evaporator varies from vehicle to vehicle, but it is generally located inside or underneath the dash. Consult the repair guide for your vehicle to determine the exact location.

Part 2 of 3: Remove the evaporator sensor

disconnecting the negative battery cable

Step 1: Disconnect the negative battery cable. Disconnect the negative battery cable with a wrench of ratchet. Then set it aside.

removing the evap sensor connector

Step 2: Remove the sensor electrical connector.

unscrewing the switch

Step 3: Remove the sensor. Apply downward pressure on the sensor to release the tab for removal. You may also need to turn the sensor counterclockwise.

  • Note: Some evaporator temperature sensors require the evaporator core be removed for replacement.

Part 3 of 3: Install the evaporator temperature sensor

installing the new evaporator temp sensor

Step 1: Install the new evaporator temperature sensor. Insert the new evaporator temperature sensor by pushing down on it and turning it clockwise if needed.

reinstalling the electrical connector

Step 2: Reinstall the electrical connector.

Step 3: Reinstall the negative battery cable. Reinstall the negative battery cable and tighten it.

turning on the ac

Step 4: Test the A/C. Once everything is complete, turn on the A/C to see if it’s working.

If not, you should have your A/C system diagnosed by a trained professional.

If you’d rather have someone tackle the job for you, the team at YourMechanic offers expert evaporator temperature sensor replacement.


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