About a month or two ago...ive noticed that there seems to be a sucking noise coming from the back of the AC controls...like a vacuum leak. If I SLIGHTLY move the switch from off over to the right a bit...but not onto the on position, it stops...but you can still BARELY hear it...but if I turn it on in any position, it goes away completely. Now, for the last week or so, I have noticed that when the AC is on, my car idles very weird...i then noticed that my ac compressor clutch is turning on and off constantly.....every 5 seconds or so the clutch clicks and starts spinning, and then stops...and then again....and at the same time my engine idles higher..a.nd then drops to normal...etc. Is this a bad compressor? If so, i'll switch over to R134. What about the controls? Also....I hear a grinding type of noise...i heard it for a long time..and replaced the tensioner pulley...and it went away for a few months....then it started again.....perhaps the compressor? Or maybe the water pump..seems to be coming from that area. Also, its been awhile since Ive been able to have the AC system on (Im sick so I dont want to freeze to death....and it has been relatively cold lately) but I dont think with the ac on there is cold air blowing...air is blowing...but I dont think its that cold...it used to be cold as hell. Any ideas?

 

Mult,

The controls in the dash are probably drying out. There is a ported vacuum selector switch connected to the position control lever. The switch is made with two chamber halves that are sealed by a heavy silicone grease. After more than a few years the grease can dry out and cause leaks in the switch. Fortunately, it's pretty easy and cheap to repair. Unfortunately, the switch has to be removed to repair it. You'll have to remove the AC control assembly from the dash.

As for the rapid cycling of the compressor, that could be completely normal depending on outside temperature. The low pressure cutout will cycle the compresor off at 25 PSIG on the low side of the system, and will not cycle back on until the system normalizes back to 45 PSIG or higher. Low side pressure can get quite low in cooler temperatures. There isn't enough heat in the ambient air to evaporate the refrigerant fast enough to keep the system at pressure. Only a few revs of the compressor can suck the receiver dry, causing the compressor to cycle as you describe.

In short, there may not be anything wrong with the system, and teh best way to find out is with a gauge set, a reliable thermometer, and a T/P chart to interpret the temperature/pressure data.