Generic electrical question (1 Viewer)

[aktundra]

I’m putting an electrical component into my 80. For the purposes of my question, it doesn’t really matter what it is. It has a plug, with two spade connectors. (I’m installing an AC compressor modified to be on board air compressor)

I have an ohm meter, but not sure I can use it for much, other than testing for 12v and beeping a ground.

Is there a way to tell which spade is intended to be the + and which is intended to be the ground ? With alligator clips and test wires, it seems to energize either way, but none-the-less would prefer to install it with the current flowing the way it was intended

 

[dallen341]

one probe into the connector (pick a position) and other probe to a good ground and check voltage. if no volts read, do continuity test from same connector (same position) to ground.

If continuity, you have your answer. You can verify by doing voltage check from other connector position to ground which should give a reading.

 

[sbman]

It does matter what it is actually. If it's something that is polarity sensitive like an electronic device, then no, your ohm meter won't help.

If it's a passive component of some kind , then your ohm meter might help, or it might not matter. Without more info there isn't much that can be said. If you are talking about the clutch coil on the compressor, it probably does not matter, unless it has diode protection in it, and then it will look like a direct short in one direction and something less than a direct short in the other, which would be the correct polarity for hook up. I don't know if A/C compressor coils have diode protection in them or not, just talking generally here.

 

[smritte]

If your talking about the compressor clutch.
1. Old school had a diode in the connector side. later this went farther down stream in the wiring. I want to say by late 80's maybe?
2. Japanese compressors are commonly one wire with the second wire (negative) going to the case.
3. The two "spade" connector compressors are not polarity sensitive and don't care how you hook them up

I have never seen anyone put a diode on the compressor side but in my lifetime, I learned never to say cant happen.

Hope this helps.

 

[aktundra]

According to the VIN on the tag from the salvage yard , this Sanden compressor is from a 1992 Dodge 3/4 ton diesel. And yes, electrical functionality is just for the clutch to engage

 

[LandLocked93]

Do not check resistance/continuity on a powered circuit with an ohmeter. The meter will be damaged (likely irrevocably).
Resistance (ohms) can only be checked on a non-powered circuit. If there are multiple devices on the same circuit, the area you are checking resistance on must be isolated from the the other devices as well.

Otherwise, you can find resistance in a powered circuit by taking a voltage drop measurement at the suspected device, then taking an amperage measurement, and then using ohms law, determine resistance.
Good luck!

 

[smritte]

this Sanden compressor is from a 1992 Dodge 3/4 ton diesel

Your good then. Polarity wont matter.