rev counter jumps when I turn air con on????

[Berty84]

Iv had my 2008 ford fiesta 1.4 tdci for 2 months or so now.. but with all this hot weather I decided to get the air conditioning serviced as it has never worked and was assured when I bought the car it just needed a re-gas...

however after the air con was done today I started the car put it on and my rev counter was all over the place jumping up and down as If my engine couldnt take the extra work from the air con then i turn air con off and all is fine...

Before all this the last week or so I have noticed a very slight rough idle when im stationery and i mean slight so I had my injectors checked over by a diesel specialist and they was fine but found a lot of carbon build up due to the injector seals leaking so I had them done for 260 quid but I still have idle problem and now its ten times worse when I use my air con

any ideas please???

 

[alan333]

Air con puts a "load" onto the engine. The engine should adjust itself automatically to compensate, ie it might increase it's revs as needed. I'd say the extra load is merely exaggerating your rough idle problem.

 

[Berty84]

Ye thats what im thinking but I dont have a clue what it is as its giving no fault codes... at the minute in kinda swaying towards my fuel pressure regulator as iv heard its a common fault on these engines

 

[Belle427]

Even with an existing problem i would not expect the revs to dance all over the place.
Maybe the fault lies with the air conditioning compressor?