Hi Dave

Like Chris Herbst, who is a regular contributor on this board and really knows his stuff, I'm confused. Try this:

First, the relays under the plastic cover at the front of the car are the Radiator fan - the aircon relay is inside the passenger compartment, under the kick panel. However, I wouldn't bother looking - not just yet. Establish first whether you need to look at it.

Here's what I would do. Look carefully at the pulley on the compressor. In front of the belt/pulley you will see the clutch plate. Start the car with the aircon OFF. Look at the plate, it will be stationary with the pulley turning right vehind it. Now switch on the aircon. The clutch plate will pull towrds the pulley and will now turn with the pulley. If not, then the compressor isn't running. It will not run if there is not enough refrigerant in the system - i.e. the pressure is not high enough to operate the Low Pressure switch.

Now, don't touch anything on the compressor.

Remove the connector on the Low Pressure switch near the firewall- I assume you've found it. Jumper the connector with a wire, and check the compressor runs.

If so, all is well. You can follow the instructions on the can and add up to 1.6 lbs of refrigerant.

If not start looking for some reason why the compressor does not operate before you do anything else =- relay - switches on the compressor - etc.

On my 850, LP operating pressure is about 45 psi at tickover - dropping to 25 psi at 2000 rpm.

KP