Toyota Matrix, 2003 model had the air conditioner suddenly stop cooling. After checking the refrigerant and seeing that it was ok I checked further and found that the compressor clutch was not engaging.
The wires all tested ok and the connections were in good shape so now that all of the easy stuff was checked it was time to get into the meat of the air conditioning system. After checking the circuitry for the air conditioner clutch and relays in the circuit we found that the M/G relay was not operation correctly. The M/G relay is located in the long black fuse box under the hood by the battery. Our M/G relay was small and white in color and plugged in so soldering was not necessary.
The M/G relay was a dealer item costing around $80.00
The parts counter person at Toyota said that they have several complaints about that relay and he is surprised that it hasn't been recalled.
With the M/G relay replaced we had no further trouble with the air conditioner.
