First the fan MUST run for A/C to work. The A/C will run if the fan is burned out but it will quickly freeze.
If you're getting the relay clicking then it should be sending power to the A/C. Is the blue "A/C" light on? Have you checked the charge? If the charge is low the low pressure switch will not allow the compressor to start or it will not allow the compressor to run for very long.
Have you looked at the compressor to see if it is turning with the A/C switch in? The center of the pulley will be stationary if it is not on and it will cycle between stationary and turning as the A/C cycles if the compressor starts.
If that center is turning all the time with the A/C on but you're not getting cool air then the compressor is probably bad. When you order a new one it's a very common compressor used by many Toyotas and Honda/Acuras so don't be accepting the excuse that they can't find one.
The low pressure switch is a SAFETY device to avoid damage to the system if there is insufficient gas in the system. It also cycles the system once it is up and running. It is not and should not be adjustable!
Have the gas checked by an A/C shop. My bet is that the system is either low or out of gas. If it has not been services for some time you probably still have R12 in there and that can get expensive if there is even anywhere that will service it in Vancouver! My A/C is running R134a which is much more readily available.
You should run the A/C once a week or so for 5 minutes just to keep seals lubricated. That usually avoids dried out seals and leaky systems.
I will get my father inlaw to check it as he still has access to r12.On my FJ62 that I had previous the aircon light did come on and the compressor did fire up even though I had a leak and no r12.Different system???
It's like a new truck! The best mod I've done. I assume you are familiar with the Coquihalla. The turbo allows you one higher gear climbing those hills. If you needed 3rd before, you can do it in 4th now!
I'm meaning that the low pressure switch on the FJ62 may have been stuck. It is NOT supposed to work with no pressure.