can't seem to clean it by myself I am not too good with audio editing ...
First off, cleaning audio is not the job of an audio editor, it's the job of a re-recording mixer.
I agree with what the others have said but I'll elaborate a bit as you seem new to audio.
Cleaning dialogue is a bit like cleaning dirt off an old painted wall. If it just needs a light dusting then all well and good but if you've got to remove stains, the act of cleaning is going to remove a certain amount of the paint as well. You might have to scrub so hard that you remove all the paint (where the stain was) but even if you don't remove it all, the cleaned part is going to look obvious and bizarre compared to the rest of the wall. Best solution would be to repaint the entire wall (re-shoot the scene/s), as even just repainting the patch where the stain was (ADR) is going to be extremely difficult to colour match the aged paint of the rest of the wall. Of course, the more skilled/experienced the person cleaning the stains and the more sophisticated the tools they have, the more chance there is of an acceptable repair/cleaning but people with a lot of experience have to pay to own sophisticated tools in the first place, so there's going to be cost involved. And, even the most skilled restorer with the very best tools might not be able to do better than an obvious patch job.
As with paint, a lot depends on exactly how noisy (dirty) your dialogue is and the exact nature of the noise (stains). Aircon for example can be anything from a quiet hiss to any combination of broadband hums, rattles, clicks, buzzes and hiss and as AcousticAl mentioned, reverb/echo is usually even more difficult to deal with.
However, I too think you should post a sample for us to have a listen to. It might be that your dialogue is more easily salvaged than we're assuming or it might be completely unsalvageable but at least you'll know one way or the other.
G
