So I'm in the process of switching over to a 7749 ECM and so I pulled my wiring harness to get rid of all the junk that I don't need anymore and have removed. I think I've covered pretty much everything except for this thing. It wasn't labeled, so either I missed it or it wasn't connected to anything when I pulled the harness. Its exactly like the AC high pressure switch that I have shown in the picture but its not that because I already removed that. I went through my GM manual 5 times and couldn't find anything. The wires going to it appear to be a plain black and plain grey wire. All I know is that its on the passenger side of the car and (i think) near the front of the engine. I thought maybe it should hook to the smog pump, but I checked an old smog pump I had and didn't see any connections for it. The only other thing I can think of, is that its part of the cooling wiring for the dual fan setup. The previous owner hacked that wiring pretty good. One last thing, when I removed my coolant temp. switch wiring I noticed it was spliced in with a wire that runs to this peice, so thats what made me think of the cooling part. I can not think of anything this could possibly be, but I just want to make sure I know I for a fact I don't need this before I remove it. Thanks in advance guys!

 

Anybody?

 

I have an identical connector (including the slot in the edge) that goes to my AC. I don't see any others that look like that.
Do you have the one you removed still?

 

Yes I do, its identical, including the slot. I was just able to get the bulkhead apart where it goes through the body, its held together by some kind of glue, and I was able to trace it back to the ecm connector and its D11 which is the AC pressure fan switch according to this webpage. http://www.eecis.udel.edu/~davis/z28...165v8tpi-6.jpg
Thats for an 86 but I imagine it would be the same for my 88??

 

One more thing. The previous plug I removed, the 2 wires running to it are blue/black & green/white.

 

Well, without a wiring diagram in front of me, I'd say that it is an A/C connector. Some cars have a low pressure, and a high pressure switch. I'm pretty sure that ALL have a low switch with others having a high switch also. In my case, I need a high switch to kick the second fan on when the pressure gets up over 250 or so to keep the A/C cold. Now I just need to find one, and somewhere to hook it up!

EDIT: Ok, I just pulled out the Haynes manual that I forgot I even owned, and according to it, the connector that goes to D11 is the fan request switch which is operated by A/C pressure. In other words, when the A/C runs, it will kick on the fans.

Hope that helps you out!

 

Sweet. Thanks alot. I guess I can do away with it then. Thanks again.

Brandon

 

I have the same exact connector just dangling on the passenger side near the ac, but I can not find where it plugs into. There is one plugged into the compressor already that looks identical, but there is no other place to put the one dangling. Anyone have any ideas where it might go?

 

I have one of those too, but I don't have AC....

I have a few that do that

 

If the wires are green and black, which they appear to be, then it goes to the A/C compressor. There are 2 connectors for the compressor, one which goes to a sensor in the back of the compressor (the high pressure switch), then another which goes right behind the pulley to turn on/off the clutch. IIRC, there is another connector close to that one on the harness which goes to something for the air injection stuff. I'm 99.9% sure that connector is for the A/C hp switch though.

 

Does anyone have any pics of both the connectors going to the compressor? I looked for a good 10 minutes and couldn't find for the life of me where it goes. There is one connected to the top of the compressor and there isn't anywhere else to connect the second line to. It looks exactly like what is pictured above. Please help me! I am really confused now. Did all models have both connections?

 

No, not all models had the High Pressure Cutout switch on the back of the compressor. Mine doesn't, but it's an 84 (originally LG4, still the same wiring). I'd have to pull up some wiring diagrams to see what ones do have it.

It seems to me that they put the high pressure cutout switch on the cars that have the higher redline. Not there on the LG4, but it is there on the L69, and the 85 TPI cars. I haven't looked any further than that. I'm in search of a switch that will come on at about 250 psi and back off at around 200, to kick my fans on for the A/C, but I haven't found such a thing.

 

I wonder why I have the connector, but no where to plug it in though? Did all models just get the same wiring harness? Anyone out there with a L03 that has this wire dangling too or is yours plugged into the compressor?

 

Does your A/C work ok? If so, I have no idea about the connector.

 

It works ok, but it cycles in and out ocasionally which I thought was low r12. I'm not gonna worry about it though because i'll be doing an r134 retrofit anyways. Like I said, it is identical to the picture above, about 18 inches long maybe, and just dangling there not attached to anything. I looked all over the compressor and couldn't find anywhere to plug it into. Maybe it was like this from the factory due to there only being 1 harness for every car???