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    Ac unit is

    Not sure if this is right place. I have trouble with my account unit..I changed it but it seems to blow out the defrost I don't want to hear the dashboard apart what could be wrong it is a 1999 grand Marquis help please

    #2
    Vacuum leak. Could be the o-rings internal to the 4 actuators inside the control head. Could also be a cracked vac line external to the control head, but that is less likely. As mentioned in the linked video, check the black vac line on the back of the control head with the engine running and vac line disconnected from the control head you should be able to feel that black line pulling vacuum. If that black line is pulling vacuum, it's most likely the common o-ring failure.

    My experience is that the '02 and older units are harder to service these o-rings; not as easy as the linked videos show. My solution for that was to get an '03+ vacuum solenoid assembly and install that in my '97 control head. The '02- assembly has separate power and ground for each solenoid while the '03+ have shared power or ground (I don't recall which), so I had to swap the electrical connector and split/splice as needed to make it work. Physically all I had to do was drill 2 holes in the rear of the housing for the screws that secure the assembly. The vacuum lines were in the same position and even use the same connector between '02- and '03+.

    This guy goes into great detail about the issue, but the second video disassembles the actuators the way that I found (per my preference) to be easier.


    (LOL, can't attach more than one video so here's a link to the second video I was referring to.)
    https://www.youtube.com/watch?v=-43OlvWP0x8
    Vic

    ~ 1989 MGM LS Colony Park - Large Marge
    ~ 1998 MGM LS - new DD
    ~ 1991 MGM LS "The Scab"
    ~ 1991 MGM GS "The Ice Car"

    Comment


      #3
      I sure could use some advice about my ac I charged the system now it wants to blow out of defrost. What went wrong I was working fine just not cool enough.

      Comment


        #4
        Hey thanks I will check it out I just want to avoid tearing the dash apart

        Comment


          #5
          LOL, looks like we posted at the same time.

          This fix will require removing the control head, and tearing it apart. A bit easier than taking the entire dash apart.
          Last edited by VicCrownVic; 08-15-2018, 08:57 AM.
          Vic

          ~ 1989 MGM LS Colony Park - Large Marge
          ~ 1998 MGM LS - new DD
          ~ 1991 MGM LS "The Scab"
          ~ 1991 MGM GS "The Ice Car"

          Comment


            #6
            Also make sure the vacuum line is connected in the engine bay. It comes out of the firewall basically in the middle and plugs into the vacuum tree. There is another hose over to the relay box on the driver's side fender. If either of those lines are not connected, or if its not plugged into the vacuum tree, you will have this problem.
            86 Lincoln Town Car (Galactica).
            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

            91 Lincoln Mark VII LSC grandpa spec white and cranberry

            1984 Lincoln Continental TurboDiesel - rolls coal

            Originally posted by phayzer5
            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

            Comment


              #7
              Originally posted by VicCrownVic View Post
              ... My experience is that the '02 and older units are harder to service these o-rings; not as easy as the linked videos show. My solution for that was to get an '03+ vacuum solenoid assembly and install that in my '97 control head. The '02- assembly has separate power and ground for each solenoid while the '03+ have shared power or ground (I don't recall which), so I had to swap the electrical connector and split/splice as needed to make it work. Physically all I had to do was drill 2 holes in the rear of the housing for the screws that secure the assembly. The vacuum lines were in the same position and even use the same connector between '02- and '03+. ...
              I tried taking apart a 02- unit in a U-pull yard, and I didn't see how it could be done unless you have the skill and patience of a dentist. Do you have any more details for the 03+ swap into an 02- unit? Does the 03+ solenoid assembly screw onto the 02- plastic or do you use the 03+ plastic in the 02- unit? [Edit: Based on the video below, it must be the latter.] And which wires go where when you splice the 02- plug onto the 03+ assembly?

              Edit: Here's a video showing the butchery you have to go through for the 02- units:

              Last edited by IPreferDIY; 08-15-2018, 06:25 PM.

              2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
              mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

              Comment


                #8
                Yep, the '02- units are doable, but given my skills/tools/patience I wasn't about to attempt it.

                Now that I'm home I have my left over parts that I can get pictures of.
                My discarded parts are the '97 vacuum actuator assembly and control head top/"lid" that it mounts to, and the '03 5-pin electrical connector.

                You end up keeping your original '02- control head but the top/"lid" gets swapped because the vacuum actuator assembly mounts to it.
                The new top/"lid" also requires drilling two holes in the rear of your '02- control unit plastic, and that is the full extent of the physical modification. I just lined the top/"lid" up in place on the control head to get an idea where the two new holes would be, marked them, then drilled with an appropriate size drill bit (sorry don't remember what size bit).


                For the electrical modification you just swap the '02- 8-pin electrical connector from the '02- vacuum actuator assembly onto the '03+ vacuum actuator assembly.
                Since it is the grounds that are switched you only need to keep track of where the grounds go. Each vacuum actuator is in the exact same location on both the '02- and '03+ units. In other words, actuator "1" controls the same function on both units, actuator "2" also controls the same function on both units... so on and so forth. It's arbitrary which actuator you call "1" and which you call "4", so long as you label them the same on both units.

                The vacuum connector on the back of the control head does not require modification. The only reason mine required it was because I installed this unit in a '91 MGM. Conveniently all the colored vacuum lines control the same function on boxes, aeros, and whales.

                Anyway, below is a picture of the '03+ electrical connector for the vacuum actuator assembly.


                And a couple views of the '02- vacuum actuator assembly.



                So what I did was take as much wiring as I wanted OFF of the '02- vacuum actuator assembly with the 8-pin connector, and left as much wiring as I wanted ON the '03+ vacuum actuator assembly while ditching the 5-pin connector.

                I don't remember if the '8-pin connector was fixed to the '02- board or if there was some other reason why I didn't just cut the 3 extra pins off the board so that the 5-pin connector could just be connected to the '02- control head board. If that way is possible then this swap becomes drill 2 holes in the back of the control head and cut the 3 extra pins off the control board (or just cut 1 pin since that is likely all that is needed to make from for the 5-pin connector).
                Vic

                ~ 1989 MGM LS Colony Park - Large Marge
                ~ 1998 MGM LS - new DD
                ~ 1991 MGM LS "The Scab"
                ~ 1991 MGM GS "The Ice Car"

                Comment


                  #9
                  Thanks. Your method should become a sticky. Judging from the looks of the five-pin plug, it might not need any pins to be cut, though one of the plastic nubs would presumably have to be removed.

                  For the 02- units, one possibility for the spot welds if the 03+ swap isn't practical is to use a suitable Dremel bit instead of drilling them. Edit: OTOH, if drilled properly, I wonder if self-tapping screws would be good enough to hold things together.
                  Last edited by IPreferDIY; 08-15-2018, 09:09 PM.

                  2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
                  mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

                  Comment


                    #10
                    You might be right, the 5-pin connector might just plug into the 8-pin spot on the control board and the extra 3 pins might not interfere at all.
                    Next time I'm in the JY I'll have to remember to compare an '02- and '03+ unit to see if I can figure out if there was any real reason I went through the hassle of swapping the connectors. Since I did this swap a bit over 3 years ago I don't remember.
                    Vic

                    ~ 1989 MGM LS Colony Park - Large Marge
                    ~ 1998 MGM LS - new DD
                    ~ 1991 MGM LS "The Scab"
                    ~ 1991 MGM GS "The Ice Car"

                    Comment

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