Auto Air Conditioning & Heater Repair: ac does not click on when i turn on the switch, refrigerant charge, chevy blazer

Question
i have a 1997 chevy blazer 4x4 that the ac doesn't work. it worked a month ago after i put a reman. engine in great. when i turn the switch there is nothing going on. i checked the freon levels and the fuses and they are fine. i usually notice the pump turn on when i flip the switch but nothing is clicking on. i don't know if it a electrical thing or a switch but i replaced the pump a few years ago so hopefully it is not the pump. i don't know if this is related but there has been a gargling sound in the dash especially when i use the defroster, heater, or the ac the floor has never been wet and i had the coolant flushed and checked for air bubbles.how can i fix these problems?

Answer
William,
First question. What was your pressure reading when you connected the gauges to the system? I ask this because the first thing I gravitate to is a low refrigerant charge. Primarilly because you say that you just did an engine swap a month ago. Now it doesn't. That tells me that when all of the hoses were reconnected, there is a possibility that you did one was not tightened fully, or perhaps one of the o-rings was accidentally left out or perhaps damaged. The o-rings are exremely important on an a/c system, but get often overlooked by most auto mechanics without a strong background in a/c.
For it to work great and then stop within the month, I would say that you have a decent sized leak. Hook up a set of gauges and let me know what you see. The reason that the low refrigerant charge would cause it to stop working is because of the low pressure switch. Without refrigerant in the system, this switch is going to open up in order to prevent the compressor from running without the refrigerant and in turn burning out. If you check the pressures, and send them to me, that will enable me to help further. If needed I will walk you through the entire electrical schematic until we find the fault.
As for the gurgling noise... can you be more descriptive. I know it's difficult to put into typed words, but it is just as difficult to try and narrow it down to an issue simply from a one-word typed description. Does it sound like when you gargle after brushing teeth? like a sink draining? How loud is it... do you have to listen for it to notice it or does it announce itself pretty loudly. On a scale of 1 to 10... volume?
Get back with me with these bits of information and I will be more than happy to do what I can.
Thank you for your question. I await your response. Good luck in everything and have a great day.