So that means the compressor coil is only dropping 0.5v. Consequently, that means that (assuming 12v) something else in the circuit is dropping the other 11.5. This confirms my suspicion that it has a high resistance connection in the wiring.

The problem is in this wire that I have highlighted. Check underneath the underhood fuse block and trace it down to the compressor. It might be easier to trace the wire from the compressor to the fuse/relay block (power distribution center).

 

OK, will look into it. Thanks a lot!

 

agreen is probably correct.

You may wish to "piggyback" another wire and see if that fixes it

the "relay trick" works like this...the 12V signal from the wire to compressor from the relay is used to trigger the relay. .03A is enough

The relay runs 12V from battery + to compressor, a fuse should be used if permanent

Google will show you how to wire a 4pin relay, you may have one laying around

As I said, its a diagnostic, like a piggyback wire

The correct permanent fix, is (once proven out) to remove any faulty wiring and replace it with (preferably) correct color, (or tagged) wire

 

Ok so I removed all of the plastic harness and tape from the fuse block, down to the first connector, then all the way down to the compressor. Every inch of the blue/black wire looks perfectly fine. Not sure what to do here. I don't really want to just cut and splice away.

 

Try removing the plug from the ac pressure switch while you fill with r134a or it will not take it if it is to low. .

 

either run a piggyback wire, or disconnect the battery and plug/connector and test the wire for high resistance

 

Just along for the tag. Between Awg and Agreen. you're on the right path (slight pun intended).

 

Interesting. You might have a bad connection where the relay goes, or it could be somewhere in the fuse box going from the power source to the relay. Let me go look at some more diagrams.

 

Relay does click on when i insert it with the ac on. I also jumped the common and normally open contacts with the relay removed obviously. The clutch didn't engage, but then when I ran another wire all the way down to the compressor, it engaged. Based on that, I would think that the issue has to be in the wire from the relay, i dont know, im pretty stumped on this one.

 

At this point, it should be simple. Refer to the schematic that agreen posted. Pin B1 gets power. When the relay energizes, it passes power to Pin B2. Remove the relay, start the engine and turn on the AC. Use a small jumper to bridge B1 and B2. The clutch should engage. Since you've already swapped out the relays and verified everything else, I can only be the wire agreen highlighted. It may look intact but may have a break inside the insulation.

If you have an ohm meter, check for continuity in that wire. Key off, disconnect the AC clutch and check from the B2 terminal to the end that connects to the clutch.

 

Ok thanks for the help. I'm getting almost 0 ohms from the relay all the way down to the compressor Guess I'll just piggyback a wire.

 

It's very possible to get 0 ohms on a wire where only 1 strand is making contact still. Or the conductors inside the insulator are broken and barely touching, giving you 0 ohms but making a high resistance when power is applied.

Try a temporary jumper from B1 to the compressor. If that works, that blue/black wire is the issue, even if it looks fine.

 

Understood. Thanks for the help!

 

I got a little caught up and forgot about the drawings. Here are the upstream diagrams for power to the clutch. Maybe fuse 9 is a little corroded?

Try this:

Place a jumper of some sort in B1 and B2. Multimeter on volts DC, check the voltage from that jumper to the compressor bracket (ground). If you get 12v, the upstream stuff is fine and your blue/black wire needs to be replaced. If it's not 12v, your voltage drop is elsewhere in the circuit.

 

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​​Below a link for a simple and clear demo on this. Skip to 02:38 min

https://youtu.be/APLic9F7ZsA