Firtst issue- When my A/C is on my car starts to vibrate a lot. It also rattles (may be something in the vent system).

Another issue- When slowing down, I push the clutch in all the way and leave it in gear. Sometimes my rpms go all the way down to just 2-3 bars. Is that common or is something wrong?

Yet another issue- (this is going to be hard to explain because I have know idea exactly when and how it happens so bare with me) Again when slowing down the same as before, usually when I'm turning the stearing wheel, I hear a clunk. From what I can tell it comes from the front left. I also can feel it in the clutch pedal. This is the problem that concerns me the most.

I have an appointment with honda on friday to raise my idle but I don't know if thats the right solution. When I told him that I thought it needed to be tuned he said that probably wasn't it. My car has 41k miles on it.

Any ideas on any of these topics would be much appreciated. Thanks!!!!

 

When the A/C is on, does the car vibrate as a result of the rpms going too low? If so, then this is not too uncommon. The extra parasitic draw on the motor will tend to cause the rpms to dip a little till the ECU has several "episodes" to learn from and then correct. If it vibrates NOT as a result of rpm drop, then something could be wrong with the A/C clutch/bearing assembly. This may be the rattle you are hearing. Any rattle in the vent system would be a result of moving air. This is governed by the fan being on or off and not by the A/C being on or off. So, if it rattles when the fan is going regardless of A/C being on or off, then it is likely NOT in the vent ductwork.

When you are slowing down and the revs dip, this may be associated with the A/C parasitic draw like already mentioned. If it does this when the A/C is NOT on, then it has to do with either the MAP sensor or the Idle Control Solenoid or both. Sometimes you can correct this issue by one of the following:
-give the ECU a few "episodes" to learn (just like with the A/C scenario).
-unplug the MAP sensor harness (just in case there is a poor connection) and plug it back in securely. While you are there, take the rubber handle of a screw driver and give the MAP sensor a few firm thumps.
-replace MAP sensor.

Your front left clunk can be almost anything. Have you struck a curb hard with either front wheel? Could be suspension or steering components.

I don't think raising the idle will be the answer. When you are not experiencing these symptoms, the idle will most likely be too high.

Oh, try taking out most of the slack in your throttle cable at the throttle body.

 

Considering your mileage, you might need valve adjustment and idle will go with it if properly tuned. Mine is doing the same thing, but I haven't gone back for another valve adjustment. Valve clearance that is out of spec. may cause rough idle.