Author Topic: A/C  (Read 13923 times)

Offline brlarl

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Re: A/C
« Reply #15 on: July 28, 2012, 12:07:09 PM »
BD can you tell me how the two dark wires receive power? They are the ones that go to the compressor and the pressure switch.  Also the brn/wht wires get their power form the selector switch once the switch is turned on, correct? Is the brown wire the power source for the selector switch? Sorry for all the questions, I guess I'm not too good at electrical like I am mechanical.  Thanks Again.
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Online bd

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Re: A/C
« Reply #16 on: July 28, 2012, 01:54:45 PM »
Ignore the hand drawn notes on the supplied diagram; they are non-factory circuit modifications that do not apply to your vehicle.

...Is the brown wire the power source for the selector switch?

Yes.  All power is controlled directly by (routed through) the selector switch.  Ignition power enters the selector switch on the 16-ga brn wire from the fuse block. 

...can you tell me how the two dark [grn] wires receive power?  They are the ones that go to the compressor and the pressure switch.

The selector switch routes power:  (1) to the blower switch and low speed blower resistor terminal via the two 16-ga brn/wht wires, and (2) to the A/C low-pressure (cycling) switch via the 16-ga lgt-grn wire.  From the 'cycling' switch, power continues on to the A/C compressor clutch, and the ECM via two 16-ga drk-grn wires.  A/C circuit feed to the ECM allows for improved idle speed control and slight adjustments within the fuel/timing matrix for improved economy and drivability.

...the brn/wht wires get their power form the selector switch once the switch is turned on, correct?

Correct.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline brlarl

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Re: A/C
« Reply #17 on: July 28, 2012, 02:18:21 PM »
Ok BD, I might have found my issue but still need your help. I was sitting in the truck looking at the power selector switch and noticed that the brn/wht wires at the power selector were in the far right slot of the plastic harness. But, when I look at the power selector switch itself there is no copper prong extending out of the switch to make contact with the wires in that position (so no power going to the speed switch via the brn/wht wire). I removed the lt green and brn/wht wire from the harness and moved them over one spot to the left to make contact with the copper points in the switch and when I flipped the switch the 25A fuse blew, so that wasn't right. Looking at the switch and harness from the drivers seat can you tell me which order from left to right should the wires be? I tried using the schematic you sent be but unfortunately I could not increase the size of it without distorting the picture so I could not read it. Thanks Again!!
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Offline brlarl

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Re: A/C
« Reply #18 on: July 28, 2012, 02:30:57 PM »
BD, I do not think that the schematic aplies to the 1990 Suburban wire harness I have in my truck. Looking at the schematic and comparing it to the hi-lo selector harness the colors do not match up. Any ideas? Thanks
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Online bd

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Re: A/C
« Reply #19 on: July 28, 2012, 03:13:18 PM »
...the brn/wht wires at the power selector were in the far right slot of the plastic harness.  But, when I look at the power selector switch itself there is no copper prong extending out of the switch to make contact with the wires in that position (so no power going to the speed switch via the brn/wht wire).  I removed the lt green and brn/wht wire from the harness and moved them over one spot to the left to make contact with the copper points in the switch and when I flipped the switch the 25A fuse blew....

Is it possible they gave you the wrong switch?  Compare it to the old one.

...Looking at the schematic and comparing it to the hi-lo selector harness the colors do not match up.  Any ideas?

Post some pics of the control panel face and the switches, resistor, relay, connectors, wiring, etc, so I can see what you're seeing.  In a new unit of time, tell me what does and what doesn't work.  Maybe we can still sort it out....
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline brlarl

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Re: A/C
« Reply #20 on: July 28, 2012, 03:32:22 PM »
Will do shortly. Thanks
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Offline brlarl

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Re: A/C
« Reply #21 on: August 01, 2012, 12:12:51 PM »
BD, sorry it took so long to re post, trying to get this done along with buying a new house.  But here are the pictures that I have.  For some reason I do remember seeing a power switch that has a copper posistion all the way to the right with a blank side just to the left of that one and then three other spots to the left of the blank spot that have the copper extensions.  If that make any sense.  Can you confirm whether Chevy has more than one Power selector switch for the A/C.  Do you know if they are diffrent from the Trucks to the Suburbans?  Thank Again
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Offline brlarl

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Re: A/C
« Reply #22 on: August 01, 2012, 12:15:48 PM »
BD, here are two more pics.  Let me know if you need pics of anything else.  Thanks
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Online bd

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Re: A/C
« Reply #23 on: August 01, 2012, 01:14:56 PM »
Your wiring is identical to the supplied diagram and posted descriptions.  Wire colors are the same.  However, the diagram has errors in the circuit numbering of the blower switch terminals.

Post pix of the selector switch and connector (unplugged) to illustrate the details of the physical position of wires in the connector and the terminals on the switch.

What does/doesn't work at this point?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline brlarl

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Re: A/C
« Reply #24 on: August 01, 2012, 01:58:08 PM »
Ok. I'll do it after work.  FYI the way the wires that are currently in the power selector I moved them.  The brn/wht wires were all the way to the right then an empty space just the the left of them then the green wire next.  So from right to left its the brown wire then an empty space then the green wire then an empty space with then the brn/wht wires.    I tried to switch the wires according to the schematic and it would blow the 25A fuse.  I'll post the pics later.  Thanks
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Offline brlarl

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Re: A/C
« Reply #25 on: August 01, 2012, 02:02:37 PM »
Nothing actually works, If I turn the A/C on the engine does idle up but no blower is blowing.  If I jump the pressure switch the compressor will run, but other than that the blower does not turn on.  I think it has to do with the dash wiring.  I may have switched wires when I added the replacement harnesses not realizing it.  Thanks
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Offline 78 Chevyrado

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Re: A/C
« Reply #26 on: August 01, 2012, 07:39:23 PM »
I'm sorry the reply took so long man.  I haven't had time to do anything lately.




That looks like the diode mine had, when i hooked it up, turned on the key that diode fried and i had to replace the relay again, but cut the relay out of the new one before hooking it up to power.  if you get power to the relay and the diode doesn't fry, it's fine. 

it only did that in my 78 though, I never had a problem on my 87.  i just thought of that, maybe being newer it won't be a problem. 
Kenny

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Online bd

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Re: A/C
« Reply #27 on: August 01, 2012, 10:12:01 PM »
BD, here are two more pics....



Look at the connector that attaches to the selector switch.  From right-to-left in your image you'll notice that each wire position has a letter, A-E.  "A" should be empty, "B" should be the two brn/wht wires, "C" should be grn, and "D" or "E" should be brn from the fuse block (D & E, if both are present, are electrically connected inside the switch).  It appears that your wire positions may be incorrect. 
« Last Edit: August 01, 2012, 10:16:59 PM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline brlarl

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Re: A/C
« Reply #28 on: August 02, 2012, 08:50:08 AM »
BD, here is a better picture of the wire harness showing the letters.  Thanks again.
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Offline brlarl

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Re: A/C
« Reply #29 on: August 02, 2012, 08:58:14 AM »
BD, What about the speed selector switch, do the wires look like they are in the correct positions?  Thanks
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