The evaporator temperature sensor can fail, causing the AC compressor not to cycle. If the AC compressor does not turn on, the AC system will not blow cold air. If the compressor is stuck on, the air will be very cold at first, before warming up.Google+
Car Problem Reports
Mercedes-Benz E320 Evaporator Temperature Sensor Failure
Mercedes-Benz E320 Problem
Average Mileage: 146,491 mi (84,000 mi - 240,000 mi)
Visitor, 1999 Mercedes-Benz E320, 100,700 mi
my a/c blows hot air after 5 mins of cold air. the compressor doesnt kick in. After doing diagnostics and found error codes leading to a bad evaporator temparature sensor
Visitor, 1997 Mercedes-Benz E320, 187,234 mi
when turning a/c on it get cold and then a/c compressor go off then turn the car off and restart a/c come back on.
Visitor, 1999 Mercedes-Benz E320, 123,000 mi
The AC would last only 5 minutes at the beginning of the day then there was no more cold air after. Heat wouldn't stay on either unless you kept it on defrost at which the fan would only run on high. It cost me $300 to fix at a Mercedes specialist shop.
Visitor, 2000 Mercedes-Benz E320, 167,000 mi
On the way, the air condition went from cold to warm. The pump worked ok. I took to a shop; and the mechanic said the pump was weak, the evaporator was leak. It would cost me over $2,200 for repair.
Just replaced this year.