Running rough when AC is turned on..

[Johnny Dart]

Hey guys.
I am working on my 74 Dart 318,all original (stock). I have given it a complete tune up (cap,rotor,wires,plugs ect). Set the timing to 10btdc.The car runs really well. When I turn the AC on the car runs kind of rough.It did the same thing before the tune-up.

There are no vacuum leaks.

Not sure what other info you would need.

Any suggestions why it runs rough with the AC on ?

 

[camd64]

the first thing that comes to my mind is that piece that bumps the idle speed up when you turn the ac on. can't remember the name of it but that could be it. also the compressor clutch going out can do that too.

 

[Johnny Dart]

The car to my knowledge didnt come with a idle compensator.

 

[camd64]

if it had been updated to a 134 setup i would say evac. it and put new oil in the compressor and recharge it, but since its probably still r12 that could cost a small fortune.

 

[Johnny Dart]

if it had been updated to a 134 setup i would say evac. it and put new oil in the compressor and recharge it, but since its probably still r12 that could cost a small fortune.

It has been updated to 134. New oil and a recharge would make it run smoother ?

I also need to check my belts a little closer.Make sure there tight and in good shape..

Also heard it could be the motor mounts.

 

[camd64]

I was figuring if it had been sitting for a really long time then the oil could have been all gummed up. but if it has already been converted then it probably wasn't that long ago.