There is a knocking when the A/C is on, but it's not the compressor. There is a visible wobble from what I believe to be part of the tensioner. Not the pulley, but from part that attaches to the block. I'm posting a pic from a stickied topic with an arrow pointing to the area and a white X on the exact wobbling piece. It is in the lower center of the pic.

 

Replace the tensioner and I'd change the belt too.

 

So apparently it was NOT the tensioner. It only does it when the A/C is on so it must be that. It was causing the tensioner to wiggle violently so that's what I thought the noise was...not! The new one doesn't wiggle as bad. So...do I have to replace the compressor or is there a serviceable part that is causing the knocking?

 

First off, what are the pressures in the a/c system? If they're very high they may be causing the knocking.

The compressor can fail and is serviced as an assembly. It's just easier and cheaper.

If it's just the clutch, it can be replaced.

 

Pressure is unknown. As far as I know the system has never been charged, so high pressure shouldn't be an issue. The system works fine, except for the knock.

 

Watch the compressor when it knocks. Is it spinning smoothly? It will cycle off and on during normal operation but once it engages it shouldn't kick right off.

Get some gauges and note the pressures, high and low.

If the compressor is bad, flush the system completely and replace both the orifice tube and receiver/dryer (Dodge calls it an accumulator). Then evacuate the system, check for leaks, and charge it.

 

Is the compressor bolted down solid if not it could be vibrating?

Get the gauges on and find out how its doing?

00DakDan has it right listen to him

 

Reciever/dryer and accumulator are two different parts

 

Not according to Dodge.

From the FSM:

ACCUMULATOR
DESCRIPTION
The accumulator is mounted in the engine compartment between the evaporator coil outlet tube and the compressor inlet.

OPERATION
Refrigerant enters the accumulator canister as a low pressure vapor through the inlet tube. Any liquid, oil-laden refrigerant falls to the bottom of the canister, which acts as a separator. A desiccant bag is mounted inside the accumulator canister to absorb any moisture which may have entered and become trapped within the refrigerant system.

 

Accumulator is on the low side service port reciever/dryer is on high side the r/d has a desiccant bag in side of it search google two different parts the reciever dryer is easly identifiable by the sight glass on top of it