It's a honda accord 2000 model,4 cylinder.D vibration also increases if I'm turning d steering or @ nyt,if I switch on d headlamp.All these don't happen if d A/c is off.D idle tym rises to slightly below 1500rpm without A/c but drops 2 1000rpm immediately d A/c is switched on.Please,what are the potential X's to this problem?

Is it the dashboard that is vibrating or the tachometer?? (engine speed reading)

From your description, your engine cannot stand much load. It has been misadjusted and will need to be tuned properly. I will also suspect the engine mounts, because I can not imagine what will make the "dashboard" to be vibrating! Unless the bolts holding it down are loose.

jubbii, i beleive d engine sitting must have broken.so go check dat 1st

1. Vaccum leak

2. Tune up

Here is one of the hoses, I guess you had someone work on the car so they either took things off or just a cracked hose

http://www.paulstravelpictures.com/Honda-Accord-PCV-Valve-Replacement-Guide/Honda-Accord-PCV-Valve-Replacement-Guide-002.html

On second pic the curved hose is what vaccum hoses look like; see if one has come off, cracked/leaking.

That metal box the hose is attached to is the throttle body, inside is a butterfly valve controlled by those cables you see on top of pic(don't let them adjust anything).Clean throttle body, check engine light should be on pull codes.