Hello all!

I have a 98 ford explorer. My AC went out last summer. Just now getting to trying to fix it. I already recharged it, with a gauge. So it's full, but my clutch on compressor still doesn't work. I tapped the clutch as it's running, nothing. I did test the compressor plug connection, i got a 3. something. I know it was average what everybody else got here. On the clutch switch, by the firewall on the passenger side, i got a negitive number. like negitive 21 or something. It didn't seem right to me. And that was with the engine running, ac max on.

I read on here to jumping the wires. I want to make sure I understand before I fry something. Just take a couple of wires from the battery, and plug it into the switch?

To add to this, if that doesn't work, do I need to replace the clutch?

I'm definitly a novice, only work on the truck a couple of times a year. So please, assume I don't know anything. Cause I don't!

Thanks!!

Rudy

 

Hello!

I wanted to clarify a couple of things. I tested the connector by the compressor, I'm getting 4.0. I'm getting 20.0 for the switch.

Thanks!

Rudy

 

The connector to the compressor clutch should read near 12 volts when activated. Much below that and the clutch will not pull in. I just replace my clutch 2 days ago and it says that right on the instruction sheet.

 

Hey 2KFord!

So do you think I need to replace the clutch. That's what I'm leaning towards?
Thanks!

 

No, not if you only have 4 volts to the coil. It's gotta have close to 12 or it won't pull in. The paper I had for my clutch says before replacement of the clutch, to pull the coil plug and verify 12v. I'm not sure what you are seeing when you say you got 4 and 20 at the switch. That can't be voltage. Make sure you have your meter on volts DC and check at the compressor coil connector again. I think you can just turn the key to run and not actually start the engine. Engage the A/C and check the volts at the connector.

 

Thanks 2KFord,

I'll double check my meter. I'll let you know!

 

Ok! I doubled check the voltage at the compressor, it is only 4 volts. I hotwired it right from the battery as well. No go on the clutch. The odd thing that I found was when I touched the hot wire to the positve battery terminal it sparked pretty big. I had the other wire connected to the positive wire on the connector.

Maybe is sounds like a bad wire, but I would of thought that it would start from the battery, but why the big spark? A bad ground somwehre?

Thanks!

Jim

 

It sounds like you coil is shorted. That would cause a large spark. Hopefully you have a digital meter. Put it on the lowest ohm setting and with the plug disconnected, measure the resistance (ohms) across the other side of the connector, the one going to the compressor. Hopefully you can get into it.

Now I'm not sure what the resistance should be, but from what I'm reading around here and other internet sites, I'm seeing that it should be around 5 ohms. I wouldn't be concerned if its more than that. You are looking for it to be 0 ohms, which would mean its shorted and also bad, which is what I believe it probably is. Reading infinite ohms would mean the coil is open, but since you had the big spark, I don't think that's likely.

I'm trying to keep you from having to shell out >$100 for a new clutch assy. until you make sure it is really bad. Even if you change the clutch, I'm still concerned about your 4 volts to the connector. That was with the connector disconnected from the compressor correct? If not, there is a diode that protects the circuit from dead shorts, and if you are connected to the compressor when you check the voltage, you won't get a correct reading.

My clutch installation paper I'm looking at here says the voltage needs to be above 10.8 volts.

Since you whacked the clutch while the engine was running (something that lsrx101 suggests) I'm really leaning toward a bad coil. My coil looked really bad when I took it off but it was still working. Unfortunately it went in the trash truck this morning so I can't check out it's resistance.

Putting on a new clutch assembly is fairly easy but the part costs me $117 with tax, and that was a 10% discount as Advanced Auto didn't have it in stock so they offered the 10% off without me asking. I think the guy was a manager. I got it the next day and I had to use some emery cloth to clean the compressor shaft, and it slid on pretty easy.

I'd like lsrx101 to chime in here and give his view just to make sure I'm not full of it. He helped me with mine the other day. I'll PM him to add his 2 cents.

Oh, and what I didn't realize when I purchase the clutch, it came with the coil as well. I found out that I should not use a new clutch with an old coil. I think it has something to do with different brands. You can buy just the coil, but I don't think that would be a good idea.

 

Hey 2K Ford!

I'll double check the connector and let you know! I appreciate all of the good advice you and the others have given. My daughter is starting school next week, and it's still as humid as a sweaty sock around here. I'm hoping it's the clutch and nothing else.

That was with the connector disconnected from the compressor correct? Yes that's correct.
Thanks again for all the help!

Rudy

 

Well that 4 volts concerns me then. I'll have to investigate my schematics.

 

Actually, I'm wondering about the meter itself. Your readings are all over the map. Put the probes across the battery and see if you measure 12-13 volts.
If it checks good:
-Attach the negative cable to the battery negative post and check the voltage at each terminal of the compressor connector.
one should read battery voltage and one should measure 0. (Engine running, AC on). If so, the clutch coil is bad.
- If not: probe both terminals of the cycling switch. Again, one should read battery voltage and the other should read 0 volts.
-
- If so: Put a jumper across the cycling Switch connector and remeasure the voltage at the compressor connector. You should see 12 volts. If so, either the switch is bad or your system is low on refrigerant.
- If you don't see battery voltage at the cycling switch connector, you'll need to do some testing around the compressor relay.
I don't have a wiring diagram handy, so do these tests and post the results.
For this particular circuit, a test light is actually the better tool. A DMM can give you flaky readings because it doesn't load the circuit down enough. It won't show high resistance ion the circuit.

 

The circuit for the 98 exploder is different from the F-series by a substantial amount. If you don't have the drawing in front of you, you will be lost.

This configuration does not have battery voltage to the cycling and cutout switches, it switches a GROUND signal to an input to the PCM which, if not grounded, will measure 4-5 VDC. The PCM then sees this grounded input signal as a valid request for the A/C to turn on. It then outputs a ground to the low side of the A/C RELAY coil (located in the under hood power distribution box), energizing the relay and switching fused (F1-10A) ALWAYS HOT power to the high side of the clutch coil which should energize the clutch.

The spark that was observed was due to the relatively large current being drawn by the coil. Since the coils are usually around 3.5 ohms, that comes out to 3.5 to 4 amps of current. Pretty significant as far as drawing a spark.

When posting meter readings, you must include the units along with the number. Without that, it's not exactly clear what you're doing.

If you send me your email address via PM, I'll email you the schematic specifically for your vehicle.

Steve

 

Well that explains why he thought that the reading was in spec with what others have seen. I wondered what was going on.

Basically then it would be nice to see the ohms across the coil, open circuit. That will tell for sure if there's a bad coil there.

 

Hi Guys!


WOW!! A wealth of info here! I did check my meter with my batter before, and it was drawing around 13v. I 'll check the rest tomorrow. We have severe weather all night, so I'll call it a night.

Thanks again, I'll let you know what I find!

Rudy

 

Hi guys!

The rains ended last night. So I did some testing. I attached my negitive cable to the negative battery post, and positive to each terminal on the connector. and my number we all over the place. Both termanls did this. So I didn't get a 12 or 0 v, I just got random numbers at a mv. I did check the resistence of the connector. Now on my little Radio Schack tester, when I put both cables together, I get 0.00 ohms. When they are apart, I get .0L reading. Not sure what that means. But when I check both terminal on that connector, I get .0L. Both ways I tried it.

So confused!

Rudy