You have a problem based upon the actual value. You will see that when you replace it. The evap temp sensor will keep the compressor off, but I'm not sure if it will light the economy button. I actually don't think it will.

You definitely need the evap temp sensor and it is not too expensive. You do need to evaluate the pressure switch issue though as it could turn on the economy position and if so will keep the AC off as the bulletin explains.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician