Ok When the car is idling or coming to a stop and the a/c is on the inside dash vibrates and it gets really bad when the fan comes on.

Also when im driving with the A/C on ill hear this loud screetching sound like fingernails on a chalk board coming from the car, the higher fan speed the louder it gets and longer it lasts. I recently put an A/C belt on the car to get the ac going and it just goes to the crank , compressor, and tensioner. Could this be a culprit. Its really embarrassing.

 

Turn the A/C on, turn it up high and listen to see where the noise is coming from. Does it only do it when the A/C is on or does it do it when just the blower is on as well?

All Civics do that rattle thing when the A/C comes on, because if you have your idle adjusted fairly low already, the fan kicking on causes the idle to bog momentaritly and your idle drops even further.

 

well the a/c wont come on unless i turn the blower on, so yes. but i havent gotten it to do it with the car at idle , on when im driving.

my idle is like 750 according to the tach.

Its an 88-91 car. Could the tach be reading to low or to high? should i adjust it to a little higher.

The car has lagged since i put the belt on

 

Let me re-ask this question.

If you turn ONLY the blower on, will it make that noise?

Also, how much deflection do you have in your belt? It almost seems like you may have it on too tight.

Also, does it seem to be coming from inside the car (under the passenger side dash) or does it seem to be coming from under the hood?

 

on no definately coming from under the hood, the blower works fines. But yeah it only make the sound when im using the a/c and have the blower going. it only makes the sound (so far that ive noticed) around first gear or when im driving slow and rev it up and thats only sometimes.

and right now the belt doesnt feel really tight, its got some decent deflection, but i need to loosen it?

 

You could definately try and see if that fixes it. If not, your condenser may be hosed and you need a new one.