My AC worked great until last year and then after a power steering hose leak was discovered, the ac until stopped blowing cold air. I took it and paid 75.00 to have it recharged with coolant and it worked again for a while and then stopped again. I had a mechanic look at it again and he pressed some button and said it had pleanty of coolant in it, that it was probably the relay switch which was under where all the power steering fluid has leaked down on it. I just want to find out if that is a possibility, if its something inexpensive and easy to change out and if I can do it myself..economic times don't allow me to take it and have it done by a professional and I need to save wherever I can.

Probably lost freon and now it won't cool. The system needs to be vacuum and pressure tested to find the leak and fix. It could be a seal on the compressor or a leak in a hose or condenser. You should see some oil leaking from the system where the leak is.

Your AC system is a closed system, so the fact you have to put more Freon in, means there is definitely a leak. I would check it out with a mechanic.

I'm sorry you have had such bad experiences with the shops.
I would have stopped at the second one and forced them to fix it at their cost.
I doubt you will be able to find the problem yourself, but I understand your hesitation to go back to another mechanic.
I will be happy to try to walk you thru the diagnostic process but it may take a few days.
First, do you know if the system is full of freon ?
If it is full, do you know if the compressor is running when the ac is switched on ?
The first shop should have discovered the blown fuse once they charged the system unless it took a day or two for the fuse to blow. The second shop that put the compressor on should have found the faulty fan, and the leaking hose if it is in fact leaking.
So should have the third shop.
If the compressor was faulty, and the system had been empty for a time, the hose could have started leaking once the system was being used. The pressure on the high side is over 200psi when the compressor is running.
Let me know where you want to start with the diagnosis after you answer my questions.

Hello
Based on what you have said and my 30 years a Ford dealer tech I believe you have a slightly low AC system refrigerant charge due to a small leak at the AC compressor or the AC line connections. I would have a shop hook up a set of gauges to monitor the pressures at idle and see just how low it is. DO NOT ADD UNTIL YOU KNOW HOW MUCH IS NEEDED, YOU CAN LOCK UP THE COMPRESSOR.

Go to Midas,they do great A.C.work,your Freon may have leaked out,they can test for a charge of 19.95..

What was the "flaw" in the friends AC system that took two years to figure out? Maybe yours has the same "flaw" and it's taking 4 years to figure out?
Don't expect your AC to blow ice when the ambient temp. is 100 degrees and you are stuck in traffic. It's not going to happen...
If your compressor is weak and not compressing properly, efficency goes down. How many miles on your truck? They wear out, like any other moving part. I suggest you have a complete evacuation done with a deep vacuum, this will remove any air or moisture. Recharge to mfrs. capacity. Clean the outside of the condenser and radiator of all dirt, debris & bugs so air flows freely....Pressure sensors and temp. switches can be tested, if they are bad, replace them.
I hope this helps.

the control module is bad it has an intermittant fault replace this and it will work fine

it will be more seals or a very hard to find leak in the evaporator core or condensor

This is very vague. Is the blower motor working (can you hear blowing inside?), is it blowing but it's hot? Can you hear the compressor running (open your hood and listen if something is kicking on and off). AC is so complex. It could be as simple as a freon leak or as complex as a compressor, hose, accumulator etc.

I had similar problem on my 2001 Insight. Had to replace some cooling system hoses eaten by rodents... Works like a champ again.