I have a 91 Ford F 150, I have replaced the a/c compressor, tank, put in a new fuse, but I have no power to the plug in that goes to the compressor. Every thing else has power, is there a wiring diagram for the a/c that someone has that they could send me or tell me where to find one, or maybe even know what my problem is, would appreciate any help as it is starting to get warm here.

Thank you

Andy P. Clevenger

 

Hi Andy, welcome to the site.
Just touching a base here. Did you evacuate the system for at least 45 minutes?
On the accumulator,tank, there should be a low pressure cut-off switch that protects the compressor when the charge is too low. There should be power to one of those wires at the low pressure switch. When we add refrigerant , motor not running yet, you will hear the switch contacts close and provide a path for current to the magnetic clutch. Then with the A/C turned on the switch will cycle until you get enough refrigerant into the system to cycle only a few times per minute.
The contacts in the plug on that low pressure switch can be jumped with a piece of wire to speed up taking refrigerant into the system, but I think it is better if you just go slow and be patient adding refrigerant.
Did you consider adding a filter to the A/C system to catch any foreign "stuff" that might not have been removed if the compressor failed and left bad things in there?
I presume you changed the orifice tube too.