air conditioning 1995 F150

There's a pressure switch near the dryer that will keep the compressor from running if the pressure is too low. You should be able to hold the can upside down and charge liquid to get the pressure up. Of course without gauges on it, it's a crap shoot.

True, then once the compressor starts after about 45 sec, turn the can upright to charge gas. Charging straight liquid can lock up the converter if it's not really low. I always do a little of both when charging from the small cans, and you can lay the can on something warm, but not too hot, to slightly raise the pressure in the can and help force it into the lines.

Also, you can unplug the low pressure switch, and jumper it with a paper clip. It'll be in the suction line somewhere or on the receiver (low pressure hose which is the larger of the two hoses) When the can top gets cold you can tell the refrigerant is moving through it, then plug the low pressure switch back in.

Those are just backyard suggestions, the proper way is with gauges and a reclaim system.

Spdloader