A/C Compressor clutch not getting power

[SCOTTY]

You can jumper(bypass) a pressure switch but risk burning out compressor if fluid is too low, or blow out a hose if pressure is too high

WOT = wide open throttle
WOT relay is 5 pin, so when its off it passes 12v to compressor clutch if AC is turned on in the cab
If you press the gas pedal to the floor, so wide open throttle, the computer turns on WOT relay which cuts the 12v going to compressor clutch, shutting AC off, so engine can make best power for passing or ???
When foot comes off the gas pedal AC comes back on

Thanks Ron,
So jumping the 2 wires @ the pressure switch won't bypass the WOT relay & it will operate as it should.
Also, & I may have missed this, but if the A/C system was left on since the last time driving the truck,
the compressor will not engage right away while starting the truck the next time, correct ?

Thank you Sir !

 

[RonD]

It won't engage when cranking the engine over, but AC will start as soon as the engine does
(when ignition switch is in START most 12volt circuits, not needed for the engine, are cut off, so all battery amps/volts go to starting the engine, this is why AC clutch would be off)

In most earlier vehicles AC is an on/off switch on one of the cab climate control switches
In 1998 and up Rangers, Ford got the engine computer(PCM) involved, it has internal WOT "relay", and shuts off AC if engine starts to overheat
Not sure what that software does on cold start or restart

 

[SCOTTY]

It won't engage when cranking the engine over, but AC will start as soon as the engine does
(when ignition switch is in START most 12volt circuits, not needed for the engine, are cut off, so all battery amps/volts go to starting the engine, this is why AC clutch would be off)

In most earlier vehicles AC is an on/off switch on one of the cab climate control switches
In 1998 and up Rangers, Ford got the engine computer(PCM) involved, it has internal WOT "relay", and shuts off AC if engine starts to overheat
Not sure what that software does on cold start or restart

So on older vehicles, let's say a '63 T-Bird, when starting it it's a normal occurrence that the current draw from the starter
stops anything else (Such as A/C) from engaging/operating until the engine is running, w/the exception of any lights on that would go
very dim ?

BTW, are these Ranger A/C pressure switches known for going bad ?

 

[RonD]

Below is typical ignition switch wiring for most vehicles

In a Ranger with key in RUN position A1, A2, A4 and I1 are powered
In START A1, A2 and A4 are cut off, only STA and I1 get power

I1 is cluster and spark system 12volts

In ACC only A1 gets 12v

 

[SCOTTY]

Thanks Ron !