My A/C compressor cycles on & off every 3-5 seconds. The hi-side won't accept R134a. What is the problem?

Question

My AC is out. I know compressors have a circuit to prevent clutch engagement when refrigerant is too low. Also, when I try to add refrigerant, the system will not accept it. Could someone tell me what this indicates? Does this indicate there is a major break somewhere? However, if this were the case, I would expect the refrigerant to be accepted into the system, albeit it would then be wasted. Can anyone help me diagnose the problem?

Sorry I was not too clear. What I meant was that the hi-side will not draw in the R134a. It is an R134a system, not R12.
I was expecting the refrigerant to flow into the system, but it does not. I am sure the can is pierced.

Thanks for the answers so far. I may (may not?) have my hi-low sides backwards; however, the fitting connects properly. So would that not indicate that I have the R134a connected properly? Or is this an incorrect assumption? It is a 94 Ford Explorer. The connector points straight up and is located just to the left of the throttle body when standing in front of the truck and looking at it. Please add more if you know (or add a new answer).
Thanks.

Answer 1

Well first off home come you are still alive. There is as much as 350 psi on the high side. You never put 134 in a high side. It always goes in the low side.
If you hook it up to the high side and open the valve will allow 350 psi into the can and it will blow up.
Always put it in the low side.

Answer 2

First of all, put the freon in on the low side not the HI. The low side will be the bigger line. Your low pressure switch is causing the AC to cycle. Before you waste the money on the 134a why don't you replace the seals, if that's what's leaking. If it's your compressor, either trade the car or fix it. It is annoying to always have to refill the freon. Better to do it right once than to keep redoing it.

Answer 3

you can get a kit at your local auto parts store that will convert an r-12 system to r-134a for around $30-$40.