I just joined this forum that I did not know existed. While searching the internet for answer on a electrical issue I am having with my 2000 Ford Ranger 3.0 Flex. The Problem: The A/C Clutch System 10A fuse keeps blowing. I've done some diagnostics. I had the truck idling and the air conditioner ran for about 20 minutes. I took it down the road and it blew again and the air quit blowing cold.

I checked the volts at the compressor clutch connector and it is 14V. so the clutch is getting power. Also the fuse did not blow when connector is disconnected.

I checked the resistance at the compressor connector insert and it read 3.7 ohms on the compressor.

What else can I check? I was left thinking a bad a/c clutch, but im thinking how can a bad clutch pop a fuse.

 

If the compressor's clutch plug disconnected prevents the fuse from blowing, then something inside the clutch is drawing too much current or shorting out. I, personally, would replace the clutch if this is the case.

If you want to, you could put a test light on the plug with the clutch disconnected. If something as measly as a test light can pop it, then that would cue you into looking at other problems.

Of course, inspect the plug and socket for corrosion and clean it up if there is any present.

If you want to, you could spring for a whole compressor. However this would mean having the system evacuated by a professional to recover the r134A, then you installing it, and of course going back to have the system refilled, unless of course you own the equipment to refill the system.

EricTheCarGuy has some videos on AC systems if you want to watch them.

 

Welcome to the forum.

The clutch coil tests as OK with 3-4 ohms, but if fuse blows then there is a problem.

Good read here on the other tests you need to do: http://www.compressorworks.com/Uploa...OIL%20DIAG.PDF

Because it took 20 minutes to blow the next fuse it could be compressor bearing is bad, heating up

 

I'm not understanding the other test....I'm completely green when it comes to finding electrical problems. My truck blew cold air fine as long as it was idling but soon as I got on the road it popped so I'm thinking the increased load caused it to pop. What would this behavior point to as far as diagnosis?

 

Update:

pulled the connector off the compressor and put a new fuse in the fuse panel....drove it to work and back and the fuse is blown again, so the compressor and clutch is good. what is next step in diagnosis.

 

Compressor may be overheating from a blockage in the system, but high pressure switch should prevent that, as far as you know neither the low pressure or high pressure switch have been by-passed right?

High pressure switch could have fail closed, not suppose to happen but..............could

You may need to take it to a shop that can test pressures, or rent a kit so you can.


Electrical resistance increases with heat, the coil that holds AC clutch engaged draws a certain amount of amps at normal operating temps.
Compressor is power by the engine but if there is a blockage it can overheat, and because it is a direct connection the coil can then overheat, which will increase that amp draw and could blow a fuse.

Feel the heat of the compressor at idle with AC on for a few minutes, then drive it and see how hot it gets

 

Even if the fuse blows without the compressor connector hooked up?

 

Missed that part

I don't have a 2000 wiring diagram but in 2001 it shows a 10amp fuse #25 in engine fuse box feeding the AC clutch Relay in that same fuse box, via Pink/light blue stripe wire.

I would pull out that relay and repeat test

 

At the moment I replaced the 10A A/C Clutch system fuse and started the truck and ac is working good. Fuse hasn't blown just like the other day. I turned ac off and on to see if the power surge would blow the fuse but it did not A/c has been blowing really good cold air while idling for 20 minutes no blown fuses at this Point. I've only just replaced the fuse. I'm thinking the fuse blows when I drive or put a load on the engine. What would cause this

 

Update: let the truck idle for an hour with AC running with no blown fuses. Air blew very cold the whole time. I do have the ac control panel out just hanging there maybe it was contacting something when bunched in there. I'm going to test it on the road when I go to work and see if it blows while driving

 

UPDATE: After running the ac for an hour at idle with the ac working great, I headed to work. I was about 100 yds from my driveway and was in second gear (5 speed Manual transmission) and the A/C Clutch System fuse blew again. I'm guessing the increased load is making it pop and that's why it doesn't pop when idling. I'm stumped on where to look next.


Fuse that keeps blowing

 

Just below that fuse in your diagram is Relay #2 AC Relay.


On your year Ranger the power for the AC clutch doesn't come from or go thru the Climate control panel in the cab.

The computer runs the AC Relay, when you select AC on the panel the Computer closes the AC relay and that pass the 10amp fuse power to the AC Clutch.

So power path is like this:

Battery--------(10amp fuse)--------AC Relay-----------AC Clutch

The Computer(PCM) is what controls the AC Relay, and this is on a different fuse

Now there also needs to be an AC Diode in that 10amp fuse circuit, but I don't see it in the diagram, only the PCM diode.
Do you see it on the AC Clutch connector?

This is a diagram of similar Ford setup: http://ww2.justanswer.com/uploads/sa...145320_v10.gif

AC relay or AC diode could be the problem, outside of a intermittently shorting wire that's all there is to that circuit.

 

I cannot find the diode you speak of mine just has to diodes in the fuse box the PCM and rear abs......both are good....I unplugged connector from compressor fuse still blows but it will not blow if the truck is sitting idle. the fuse only blows when I begin to move the truck forward or backwards in gear. it does not blow when i push the clutch in and put it in gear, but as I release the clutch and the engine takes the load and the truck begins to move, the fuse blows. tested it with 2 fuses. the fuse blew even though the truck rolled 2 ft. I tried rolling the truck in neutral, hoping a wire was touching the wheels or something that blew it and the fuse did not blow while the truck was rolling in neutral. the fuse only blows when i released the clutch and engage the transmission with the engine and begin moving the vehicle....im thinking it has something to do with the increased load on the engine is blowing the fuse but i dont know what to do next except find this diode and test it. I tested ac relay and its good.

 

You may need to get a 2000 Ford Ranger EVTM

Google: 2000 ranger evtm

EVTMs are electrical vacuum troubleshooting manuals
These are made by Ford and sent out to Ford Service departments with each model and year.
They will have exact wiring and locations for your specific year, a 1999 or 2001 will for sure be different, but AC may be the same, just never know.
Often called Shop manuals, but shop manuals can be generic and not year specific like EVTMs

In my 2001 it shows fuse #25 10amp as the only thing hooked to AC relay, in your drawing it is labelled fuse #1.
In my 1999 diagrams it shows fuse #1 10amp as AC relay fuse, and nothing else uses that fuse.
So not sure if AC Relay is the only system using fuse #1 in 2000 Ranger

All AC systems have and need that diode, and a diode is a Ground, so would blow a fuse if failed.

Your engine load issue doesn't fit unless something else is sharing that 10amp fuse, and even then engine load doesn't create electrical issues, movement can if a wire is shorting out when you move.
You could get a volt meter and test voltage at battery with engine running at idle and then at say 2,500RPM
After startup voltage will be above 14volts but below 15volts
After recharge cycle, 5 minutes or so, it will drop to 13.5-13.9volts
Increasing RPMs will raise voltage initially but is should stay under 14volts as voltage regulator reacts to higher RPM and lowers it
At idle turn on all electrics, head lights, fan to high, radio, ect.........
Voltage should drop with each power draw and then come back up to what it was, voltage regulator reacting to power draws.

You could use volt meter at Fuse #1 to find out which side of the fuse is the Power side and which is the Load side
Pull out the fuse and test which side of the socket has power, thats the power side, other contact is the Load side
Switch to OHM meter, set OHMs to lowest number if available, 200 or 1k OHMs, put probe on Load contact and other probe on Ground, battery negative
Should see very high OHM number or N/C(no connection)
Start engine and turn on AC
With AC relay closed you should see Field Coil OHMS, 3-6ohms
Now move any wires in engine bay around, you are looking for drop to 0 OHMs, dead short that would blow a fuse, if you have a helper have them pull truck forward a bit while you watch the OHM meter.

And use volt meter on Power side for same tests, seeing if you get a voltage spike, although thats a long shot since other fuses would also blow since they share a common bus(power connection)