Can anyone help? I have a 94 3.0 with 145,000 miles. Up until two days ago my A/C was working fine. I noticed that the A/C wasn't cooling and I also realized that the A/C compressor wasn't turning on like it use to. I could usually hear it kick in when I turned on the A/C. I did some looking around and noticed that the #6 fuse for the A/C compressor was shot. It's a 20 amp fuse and I replaced it with another 20 amp fuse. As soon as the A/C compressor went to turn on the fuse blew. I tried a 30 amp fuse and a 15 amp fuse. All of which blew in the same fashion. Any ideas on how I can keep it from blowing and fix my problem. Thanks

 

If I had a 94 Aerostar I would also have the Electrical troubleshooting manual for it & could tell you more. Try removing the connector from the compressor clutch & see if the fuse still blows. What does your owners manual say fuse 6 is wired to besides the compressor? And if your owners manual sez fuse 6 is 20 amps do not use anything else.

 

Thanks, I'll try that. I have the haynes manual. I'll take a look at it, but looking at an electrical skematic is very new to me. Thanks

 

I disconnected the only wire leading into the compressor and once again the fuse still blew when I turned on the A/C. When I replaced the fuse and didn't turn on the A/C the fuse won't blow allowing me to use the cruise control which is apparently tied in with the A/C fuse. Any more ideas anyone.

 

Maybe it's the actual a/c switch that 's burnt out? Put 12v directly to compressor wire at compressor and see if it blows.

 

I've got a Haynes and the EVTM for the 94. Maybe I can help.

The power comes from the 20A fuse to the control panel. When you turn the A/C on the power then goes first to the Clutch Cycling Pressure Switch, Then through the Refrigerant Cutoff Switch and then splits. It goes to 2 places.

First is the Powertrain Control Module. This increases the idle speed when the A/C is on.

Second, it goes to the A/C WOT Coutout Relay. It passes through the relay and goes to the A/C clutch (and Clutch diode).

Now, to blow the fuse you must draw too much current. You are drawing in excess of 20 amps if the fuse blows. A smaller (15A) will not help. It should blow. Putting in a bigger (30A) is dangerous. If you draw more than 20 but less than 30 the fuse will not blow but the wiring is rated for a max of 20. Potentially you could start a fire. Not a good thing.

So, the problem is too much current (too large of an electical load). This could be caused by the clutch drawing too much power or something shorting to ground.

Since you disconnected the compressor/clutch and the fuse blew then It will not be the compressor/clutch. Since it does not blow when the A/C is turned off then the problem is downline from the instrument panel where you turn it on and off.

I would disconnect the Clutch Cycling Pressure Switch first. See if it still blows the fuse. This is located behind the air filter box. It's the black canistor that normally gets cold and wet when the A/C is on. There should be a connector on the side of it.

If it does not blow then I'd disconnect the Refrigerant Cutoff Switch and reconnect the Clutch Cycling Pressure Switch and try it again. If it blow now it was the Clutch Cycling Pressure Switch.

From there you have to try the A/C WOT Cutout Relay. This is controled by the PCM and will turn off the A/C when the engine temp is too high or under Wide Open Throttle (WOT).

Basically it comes down to one of two things. Either some wiring has come into contact with ground and is blowing the fuse or one of the components has shorted to ground and you've just got to narrow it down.

 

Thanks Tom!! I hope to have time tomorrow to play with it providing the "Honey Due" list is not to long. Just to add something to my earlier post which maybe could play a large role in finding the problem to this fuse. I bought the car used a few months ago. The owner told me the a/c had stopped working just before I bought it even though he recharged the system. When I got the car I checked all the fuses and if I recall properly the 20amp a/c fuse was blown so I replaced it. The A/C started working without problems. I did notice however that there was a clicking sound coming from directly behind the A/C switch on the console and the only way to describe it would be the clicking sound of the old "telegraph system". It would seem to happen intermittingly and more often when I would hit bumps in the road. Although this continued, the A/C still worked fine until a week or so ago. Since the fuse has been blown the clicking sound is now gone of course until I replaced the 20 amp fuse and didnt turn on the A/C the clicking sound came back. I will definately try your suggestions and post the outcome for your viewing. Thanks!

 

i think the clicking sound is a wire grounding out