Hello All
I have a 2001 Ford Ranger 4.0L. The A/C Clutch will not engage. System is fully charged. Looking to start with the easiest and working my way through. Should I start by checking the Fuse-relay? If so, is there another relay I can temporarily swap it with to check if its' bad?
Thank you

 

Welcome to the forum

First start at the compressor
There is a 2 wire connector there on its clutch, see if the grey/white wire has 12volts with engine running and cab switch with AC on
If it does then problem is the Clutch field coil, its not working

If it doesn't then could be a fuse or relay, or pressure switch
Check fuse 10 in cab fuse box, 7.5amp, this is used by the cab AC switch to send 12volt to the computer telling it to turn on AC clutch relay

Check Fuse 25 in ENGINE fuse box, 10amp, this sends 12volts to AC Clutch relay to power the clutch

If fuses both check out, then you can swap AC clutch Relay with a wiper replay they are usually the same, to test if its a relay issue, but unlikely to be a relay issue

There are 2 pressure switches, a high and low pressure switch, either of which can fail
You need an OHM meter or continuity tester
unplug each switch and test if the 2 contacts show 0 ohms(connected) or have continuity(connected)
If either is disconnected then either that switch is bad or system pressure is bad
Switches can be changed without draining the system

Both switches are closed(good) that allows AC clutch relay to close and send 12volts to the clutch on compressor

Just to surmise
The AC switch in the cab sends 12volts to computer
The computer will then connect pressure switch wires to AC Relay(grounding it)
AC relay will close and send 12volts to AC Clutch on compressor

 

This is great info! Thank you. Truck is my son's so I need to get to him before I try these steps out. I'll let you know
Thanks again RonD

 

Quick question:
I havent checked it yet, but #10 fuse in Cab says "Speed Control Servo/Amplifier Assembly, Generic Electronic Module (GEM), Shift Lock Actuator, Turn Signals"

 

Yes, Cab fuse 10 does all those systems and AC demand power to computer

 

Hello - I was able to check the voltage at the compressor. It is not 12v. Is it normal for it to fluctuate? It's fluctuating between 4-6 volts.

 

You have a corroded connection somewhere

Pull out the AC Clutch relay in the engine fuse box
With KEY OFF
Test each slot in the relays base, there are 5 slots
One should read 12volts(battery voltage)
If so, then Fuse 25(in engine fuse box) is OK, passing full voltage, so wire from relay to compressor is bad

If not then pull out fuse 25 and test its 2 slots, one should read 12volts
If so then wire from that fuse to the AC Clutch relay is bad

The 12volts to activate compressor comes from fuse 25, not the switch on the dash or the computer, these operate the AC Clutch relay, close it to send 12v from fuse 25 to the compressor

 

Thanks again for the info!
I tested the Relay and one of the slots DID read 12volts. So does this mean the wire from the relay to compressor is bad? Do I need to replace that wire harness, or can I get away with changing/swapping out the 1 wire, if I can isolate it of course.
NOTE: I bypassed the low-pressure switch with a paper clip and the compressor does engage. However, I replaced the Low Pressure switch, but that did not make a difference. Clutch will still not engage with new switch/sensor.
Thoughts??
Thanks again

 

If you jumped the low pressure switch and AC clutch engaged then all the wiring is OK

If new low pressure switch didn't fix it then your pressure is TOO LOW, so its a "freon" system issue not electrical

pressure guide here: https://www.autozone.com/diy/wp-cont...2-1024x589.png

Outside Temperature matters ALOT when testing pressure
If low side is too low and you run the compressor it WILL burn out

You need to get an AC pressure gauge set, two gauges so you can see BOTH high and low at the same time, this will tell you if you are just low on "freon" or system has a "bockage" and needs to be drained and flushed, then replace Orifice tube and receiver/drier and refill

You can re-install the jumper on the low side switch to turn compressor on just for testing

Look here: https://aa1car.com/library/ac_diagnosis_chart.gif

Duct Temp means the air temp inside the cab with AC and fan on

 

Thanks. With your recommendation and now knowing the compressor and wiring were OK I had it charged. It worked great for about an hour but then went warm. I obviously have a leak, just need to find it now
Thanks again

 

Yes, you have a leak
Most new refrigerant cans have a dye in them, should say that on the can

Often need a UV light to see the dye
But some are visible as yellow or green marks/leaks

Condenser in front of the radiator is the most common leak point as it has the highest pressure in the system, also one of the more expensive parts to replace