My Echo screeches when the AC is on. If I hit the gas, the sound will go away. Also, sometimes when I’m slowing down the screech starts with the AC on. Occasionally, the sound goes away after I’ve driven about 20 - 30 miles; it appears that the car at idle then is idleing a little higher. And, lastly, on very rare ocassions, the screech will start when the AC is off and I turn a corner. I’ve had this screech for years and the Toyota folks just ignore it.
Have a mechanic check the tightness of the belt that drives the A/C compressor.
More than likely, he will find that the belt tensioner needs to be replaced, and that the belt is also ready for replacement.
I had a similar problem. The solution was just a matter of tightening the belt. Follow VDC’s advice and have a mechanic, not necessarily Toyota, check the belt.
The belt is not staying tight when the AC is running. It could be a bad belt or a bad belt tensioner. Have a good independent mechanic check it out.
The Echo does not have a belt tensioner.
This post is 8 months old.
+1 for BustedKnuckles. BondKennyBond…I believe the alternator serves as the “belt tensioner” in this case like the automotive industry used for decades.