compressor short cycling

[mobil_12]

I have been looking at a 1996 FCV interceptor for the local sheriff department. The compressor is short cycling. It has a full charge, I recovered it to see and it was full. With the guages on, the low side switch closes at 48 psi and opens at 24 psi like it is supposed to. The problem is, that the time inbetween opening and closing is just a few seconds. Once the switch closes, the pressure drops almost imediately to 24psi and the switch opens. It is still cooling fine, but the officer is complaining about the rapid power surge on the highway every the compressor engages.
I first figured a blockage on the low side causing the pressure drop. So I pulled it down again and took out the orifice tube to replace it. The tube was covered in metal bits. I am assuming they came form the compressor, but I have never run into a compressor that drops pressure like that.
Am I on the right track or am I completely wrong about the compressor? Does this sound like a compressor problem? Or maybe a restriction on the low side? Any ideas would be great help. Thanks.

[reekor]

I hate to tell you this but it sounds like it's low on refrigerant, I had the samething heppen on a 94CV and for some reason filling the system by weight does not seem to work. Start the car crank the ac to max fill it until the compressor stops kicking in and out, let it run another 5 minutes and charge the system while running to 35psi in around 75-80F degrees of outside ambient temperature.

Originally Posted by mobil_12

I have been looking at a 1996 FCV interceptor for the local sheriff department. The compressor is short cycling. It has a full charge, I recovered it to see and it was full. With the guages on, the low side switch closes at 48 psi and opens at 24 psi like it is supposed to. The problem is, that the time inbetween opening and closing is just a few seconds. Once the switch closes, the pressure drops almost imediately to 24psi and the switch opens. It is still cooling fine, but the officer is complaining about the rapid power surge on the highway every the compressor engages.
I first figured a blockage on the low side causing the pressure drop. So I pulled it down again and took out the orifice tube to replace it. The tube was covered in metal bits. I am assuming they came form the compressor, but I have never run into a compressor that drops pressure like that.
Am I on the right track or am I completely wrong about the compressor? Does this sound like a compressor problem? Or maybe a restriction on the low side? Any ideas would be great help. Thanks.

[jimmytroanoke]

With the blocked orifice, are you sure the high side cutout isn't the one cutting it off? If the orifice is partly blocked the high pressure could go too high and force it to cycle. If you have metal in the orifice, it sounds like the compressor isn't too long for this world!