A/C Compressor clutch not engaging

Roy,

Thanks for the reply and appreciate the speedy reply. Have family over this evening, may be a day or two before I can get back under the hood but truly appreciate the information and the diagrams. I will follow back up with my findings.

John

Roy,

Not sure how this happened but may have been the result of using the thermal fuse. I'm picking one up today on the way home, hope to get it replaced and then I'll be checking the lines with the diagrams you provided. Photo attached of the plug on the compressor.

I also updated my description to give you a bit of background as well.

John

Roy,

The picture of the connector, while there may be some corrosion there, the biggest damage is, it's melted and may not allow for proper mating but I'll get to that after I confirm the wiring diagram first.

On the diagram, A/C Compressor Clutch Relay, IGN E fuse 10A, not finding it. I see the relay and the A/C compressor fuse but not the IGN E fuse. I'm attaching a diagram from under the cover and maybe I'm overlooking it?

On the A/C compressor fuse, I do have 12.5 VDC on the one side. I just need to find the other fuse, unless it's labeled different?

I'm also attaching a picture with me pointing at what I think is the under hood engine control module, on the left front side of the engine compartment, next to the battery and fuse box?

John

Never mind, found the fuse. I'll let you know.

Roy,

Okay, tested for the 12 14 volts on the two fuses. Present. I'll have to check next if the voltage is getting to the plug at the clutch.

Am I to understand that when the ECM detects the signal that the A/C in the cab has been turned on, it supplies the ground to the relay so that it will engage the clutch?

It'll be tomorrow before I can get back under the truck and do a voltage check at the plug to see if it is present.

And another question. Is it possible the compressor is still functioning but the clutch is failing?

John

Roy,

Got under the truck and disconnected the plug at the compressor. Had my wife crank the truck and turn the AC on. I put a meter on the green wire and to ground, reading was 0 vdc. Both fuses were still intact. I even replace the relay to no avail. I haven't tested the slots on the relay yet. Working on getting test clips and use something like a paler clip to make sure the voltage is there when the AC is turned on so it should energize the relay like it should. I'd the voltage is there to energize the relay then the control module is doing it's job. My other thought is, if the switch in the cab isn't working to send the proper signal to the ECM, then it (the fan or AC engage switch. Not sure of the exact name but the snowflake switch) could be the culprit.

I'm going to create a wire long enough to reach my meter and perform a continuity check between the plug on the compressor (green wire) to pin 87 on the relay and make sure that wire hasn't melted somewhere along the mix.

Your thoughts.

John

Roy,

I looked back and didn't see any reference to checking any pressures either low or high but I've overlooked things before.

I will see about getting a gauge on there and checking the pressures.

I remember a former test where you can jumper the plug at the low pressure side to engage the clutch but don't remember the procedure. That was done a few months back and it passed then but things can change.

I'll let you know what the pressures are once I get my hands on a pressure gauge.

John

Roy,

I put the gauge on there but not sure what is a good reading. Photo attached.

I also checked to see if the relay was engaging when the air was turned on in the cab. The relay did click when I turned on the air.

John

Roy,

No, while the relay did click, the compressor did not turn on. I do have a replacement plug. That'll go in this afternoon after I get home, out in errands.

John

Roy,

Finally got back under the hood. I tested for continuity from the compressor to relay contact 87. 0 ohms.

From the 10 amp A/C compressor fuse to pin 30. Infinity. That explains why the compressor wasn't kicking in. So, instead of replacing the fuse box or trying to dismantle the fuse box, I ran a 16 gauge jumper from the fuse to pin 30. Picture attached.

Compressor kicked in, cycled twice and then nothing. Checked the fuse, still good. Snapped a picture of the gauges while the clutch was engaged but that doesn't look like it's right. That picture attached as well.

John