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My 94 Buick park avenue blows cold air fine, but I often hear a clicking sound which was isolated to the compressor as it engages and relaeses every few seconds when turned on.  A schematic showed a relay for the compressor control and I guess its defective.  Should  I replace this and where might I find this relay?  

What is the low side pressure?  

It also could be normal unless you have max ac selected. It will depend on the pressure and the EVAP temp.  

I don't have info on the low pressure of the A/CC system. It is engaging in 3 second intervals and I can see the clutch grab and releaseplus there's a loud clicking sound.  I think its a relay coil that has lost some of its magnetic strength.  

Then swap the relay with the ABS relay see what happens, you are flying blind without A/C manifold gauges though.  

Thats a great idea, yet theres about six relays and their not labled.  If i pull them out will the label be behind?  

As long as they have the same part # swap away on any one.  

i'm stuck.  I don't want to pull out all the relays without i.d. of them.  

You will be okay all the relays in that location are NO type you can swap any of them for the A/C relay. To find out which one is the A/C relay have someone turn on and off A/C while touching end of relay you will feel it click as it is energized.  

great idea!
 

The relay is fine . I located it and switched it with another and I can feel it clicking as the compressor clutch goes on and off.  The schematic traces the relay back to compressor control in the powertrain control module which in turn gets it's current from 2 cycling switches in series(A/C Hi pressure cut-out and A/C Press) that end at mode select in the Heater & A/C control assembly. The relay is getting its false commands from somewhere  There is another A/C solenoid switch assembly that has an A/C request line in it that goes over to the Heater & A/C control assembly. I think its an electrical problem.  

Borrow a set of gauges..report back with the pressures...don't hang any parts.