Help with AC compressor clutch wiring

[tbrumm]

So I ditched the crappy dealer AC that I have fought to keep working the 5 years and installed the under hood plenum and wiring from a 1995 parts truck. The wiring in the plenum connected up directly with the cab harness under the passenger's kick panel. Turning the heat/ac dash control to AC, I have power to the pressure switch on the accumulator. So, I connected a jumper wire between the two terminals in the pressure switch connector. No power to the AC compressor clutch though, at least not to connector that actually connects to the compressor - the two wire "flat" connector that is. The two wire flat connector has a gray/white wire and a black wire but no power. The "other" connector on the engine harness that is nearby is a 4 prong connector with only two wire running into it-a black yellow wire and a green wire. The black yellow wire receives power when turning the AC control to AC and shuts off accordingly. I am confused here. the connector that should work with the compressor has no power by the one that won't connect to compressor has power when it should. Did the 1994 trucks use the 4 prong connector to connect to the compressor? Neither of these two connectors had been used with the dealer installed AC, as that compressor just had a single wire for power connected to it. Any guidance on this would be greatly appreciated!

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[tbrumm]

Well, after more research, it would appear that the harness in my truck is missing a part - the AC jumper. This short section of harness apparently contains the diode as well. It may look like this

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I only found a callout name "19D887" but not the full part number. This would seem to plug into the 4 prong connector and then connect with the two prong connector to the AC clutch. Anybody have a full part number or have one laying around?

 

[Cruiseomatic]

Interesting. I must have the very long version of that then...

 

[DaveBen]

The full part number maybe under the gray tape. I see a FORD part number on the red tape...

 

[tbrumm]

The full part number maybe under the gray tape. I see a FORD part number on the red tape...

It may be. Unfortunately, that is just an image I pulled of the internet, so I can't look any closer. It appears than many of these AC jumper harnesses are the same across different models. They are simply a small harness containing the diode, the connector that hooks to the engine harness and then the connector that hooks to the AC clutch. Since my truck did not have factory AC, I have "most" of the harness but not this particular jumper. I didn't know I needed it when I got my used AC parts, other wise I would have looked for it. The Ford service manual I have kind of skips over this part, and I haven't had much luck finding anything on line. A few on E-Bay of course. Can anyone take a pic of their harness at the AC compressor and post it up so I can compare? Thanks for any help!

 

[ifrythings]

The 4 pin plug is the high pressure cutout switch which is in line with the clutch, jumper the 4 pin and you'll get power at the 2 pin. I do recommend getting the high pressure cutout out switch if your going r134.

 

[tbrumm]

The 4 pin plug is the high pressure cutout switch which is in line with the clutch, jumper the 4 pin and you'll get power at the 2 pin. I do recommend getting the high pressure cutout out switch if your going r134.

Thanks for the reply! So there is a high pressure switch involved here too. Does this plug into the 4 pin (which only has 2 wires)? Any chance you would have a pic or part numbers? I didn't realize there was another switch needed here so I will do more research. Thanks again!

Edit: So that switch is apparently plugs into the round (what I am calling 4 pin with two wires) connector. The switch has female threads on one end - where does this mount on the high side line? I will have to look on the compressor or line and see if there is a place for this - must be.

 

[ifrythings]

The switch is right above the ac compressor in the pic below

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And here's what the switch looks like

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And is ford part number MOTORCRAFT YH1705

 

[tbrumm]

You are the man, ifrythings! That was the missing piece of my AC puzzle! I really appreciate the help! I picked up a high pressure switch at O'Reilly's on the way home tonight, installed it and I have power to the AC clutch That is, when I jumper the low pressure switch. I don't have the system up to full charge yet, but I am close to having a fully functioning factory AC system!

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[ifrythings]

Glad you got it going, now get the proper charge in the system and enjoy that ac!

 

[tbrumm]

Glad you got it going, now get the proper charge in the system and enjoy that ac!

Yeah, too bad it is November. I will have to wait until next summer to really get the use of it. It was almost 80 here today though.