• still lacking 12 volts to AC compressor
  • still lacking 12 volts to AC compressor
  • still lacking 12 volts to AC compressor
  • still lacking 12 volts to AC compressor

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  1. #1
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    Default still lacking 12 volts to AC compressor

    Replace the AC programmer, now the air blows where it is supposed to. although the blower speed does not seem to blow as hard as I remember on my 93 Vette

    The head unit seems to work properly. No codes (c68)Even when you pull the codes the 00 shows no problems and #9 seems to indicate correctly what it should be doing , when I drop the temp. the #9 shows that the ac is (#2) same with the heater (#4) the heater does work. but the compressor has never engaged. 12 volts direct to the clutch works. I already tried jumping all of the switches.

    I replaced the relay.

    When something breaks on my 69 GTX it's pretty easy to diagnose and fix.

    I guess that is what I get for trying to apply 35 yrs of knowledge from early Vettes and Mopars to a rolling computer.


    I usually not one top give up on these things, But any suggestions would help.


    I do have all of the FSM and I understand how to read them.

    I don't have a tech 1 scanner but I am looking on line for one.

    I already replaced the ECM with a rebuilt one.

    Thanks

    Bob

  2. #2
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    I'll take a shot at helping, since we share the Mopar background I guess you can't be all bad. I have a Tech 1 and it would be of some help since it is similar in operation to the DRB but hope we can figure it out without one.
    Understand any suggestions I make will be based on my 93 Vette FSM because it is the only one available to me.
    My first one is going to be to verify you have 12 volts at terminal 85 of the clutch relay. Rather than do it with a DVOM I suggest a test light, it is a simple power supply wire and not connected to electronics.
    If you have power then try grounding terminal 86. That is the A/C clutch relay control from the ECM, which simply grounds the relay to close the coil sending 12 volts to the clutch field.
    Assuming the wiring is the same for our cars the wire color to terminal 85 and 87 should be brown, the one from the ECM to terminal 86 will be dark green with a white tracer. Please let me know the results.

  3. #3
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    toptech,

    I Checked that and I am getting 12 volts to both terminals. I next tried jumping the brown wire (both of them one at a time to the green wire( no tracer on the 90) that goes to the high pressure switch. According to the FSM that should have engaged the clutch, but of couse it didn't!! nothing happened so now I am at the high pressure switch getting ready to test it to ground. How am I doing so far??

    I figured if I can take a 69 GTX which was a shell with all of the stuff in 15 boxes with a little help I might get this fixed (if it doesn't kill me). I see you are on line I might wait for youy next post before proceeding.

    Thanks

  4. #4
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    No voltage to the high pressure switch FSM says is a short in ckt 66.

    OH Boy my lucky day, I would rather chew nails than chase electrical shorts. Old Mopars ruined me on that one.

    where is the 150ckt ground?

    Thanks

  5. #5
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    Default

    Whoa, slow down, if you did what you said you just put 12 volts on the ground wire going back to the ECM according to my wiring diagram.
    Do you have the 91 FSM?

  6. #6
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    I have a 90 fsm

    What it said to do was to check both brown wires for 12 volts to ground I did that and got 12 volts from both brown wires , Then it said to jump ck50(brown) to the green wire (ck66). I did that ,since it didn't say which brown wire to use i tried each one, one at a time.

  7. #7
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    rig it sounds like the wiring has some differences so let's try this a little differently. Can you e-mail or fax the diagram you are working with? If you check your PM you should find a message with my regular e-mail address.
    To answer your question my book shows circuit 150 (clutch ground) going through splice 130 to ground G109 located on the right frame rail in the engine compartment. But since the clutch engages when you jump 12 volts to it, the ground should be good.

  8. #8
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    Quote Originally Posted by rlg View Post
    I have a 90 fsm

    What it said to do was to check both brown wires for 12 volts to ground I did that and got 12 volts from both brown wires , Then it said to jump ck50(brown) to the green wire (ck66). I did that ,since it didn't say which brown wire to use i tried each one, one at a time.
    Okay I think I understand but it is hard to follow since the circuit must be different. I have no circuit 66, the power circuit to the clutch in my book is 59 (dk green) and it only goes to the clutch and ECM. If you contact me using my regular e-mail maybe we can get on the same page.

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    Toptech

    your email didn't show up , if you have a fax, I made copies and can fax or I can scan

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    Understood rig, but I do not want to post my e-mail or phone number on-line. I will try again to send you a PM or e-mail through the forum, make sure your settings will allow you to receive.

    I got your friend request and allowed it but I can't even find you in the member list! Got to be some problem with the forum, strange.

  11. #11
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    Quote Originally Posted by rlg View Post
    I have a 90 fsm

    What it said to do was to check both brown wires for 12 volts to ground I did that and got 12 volts from both brown wires , Then it said to jump ck50(brown) to the green wire (ck66). I did that ,since it didn't say which brown wire to use i tried each one, one at a time.
    I went online and pulled up your wiring diagram and followed the thread a
    nd posts to this point...if you're heading for the high pressure switch
    I would leave the brown wire (either one) jumped to the green wire..use a test light and check the green wire at the high presure switch then check the black/white at the high pres. switch thenlooks like a straight shot to the low pressure switch. Check voltage at black/white wire of low pres.switch...if you have voltage there and on the blue wire out of the low pres. switch .....then there is either a break in the blue wire itself or at the splice (S126) where one wire goes to the ECM (AC on input for IAC control when compressor engaged) and the other runs to the AC clutch itself. IMO looks like you're getting close to daylight

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    topteck,twister,

    I will be back at it today.

    Will let everone know how it turns out.

    Thanks

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    toptech,

    I got 12 vots at the green wire without grounding the brown one.

    I am going to try again in a while just to make sure I didn't dream it.


    c100 is the bulkhead

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    Quote Originally Posted by rlg View Post
    toptech,

    I got 12 vots at the green wire without grounding the brown one.

    I am going to try again in a while just to make sure I didn't dream it.


    c100 is the bulkhead
    Not trying to steal the thread but ,....do you mean without jumping the brown one ?

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    jump right in, I was talking to top yesterday and that was where we left off.

    jumped brown and green no voltage at the hp switch, pluged in the relay and I can hear it work I get 12 volts to both brown wires and the green wire at the relay. it looks like a straight path to the switch.

    What do you think

    Thanks

    Bob

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