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    #1

    Possible vacuum problem

    Short version: When set on MAX A/C under light throttle it will default to floor/defrost, when on NORMAL it defaults under medium throttle. There is no hissing noise but this does sound like low vacuum.
    I am going to look into it this weekend with a vacuum gauge. The hoses and lines look ok under hood. And I have not done the self test as of yet, will it give a code for low vacuum?
    Any suggestions on where to start?

    03 GM
    Auto Climate Control
    Tags: None
    #2
    the check valve under the hood at the firewall. it will have a T on one end and the other end will be connected to the vacuum tree. It may be hard to get to. It won't give codes for vacuum since it's not actually leaking from the engine's view. The check valve just isn't checking any more. I've had this problem with more than a few vehicles and that's always been the issue (twice on just my 88 MGM. first replacement check valve was crap)

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

    Comment

      #3
      That would make sense since I hear no leaks, and i was talking about the A/C control self test not the PCM
      I will check it this weekend and report what i find

      Comment

        #4
        oh... that's right... the new systems have a self test. I keep forgetting that. I still don't have an OBDII car much less one with a smart AC system.

        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
        rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
        Originally posted by gadget73
        ... and it should all work like magic and unicorns and stuff.
        Originally posted by dmccaig
        Overhead, some poor bastards are flying in airplanes.

        Comment

          #5
          Those cars have the plastic vacuum canisters on the fender instead of the coffee cans. I bet it has a hole somewhere in it. My car did the same thing when I replaced the can with the plastic tank of the later boxes. Pretty sure the Whales use the same set up as the aeros as well. Should be somewhere on the fender well.

          Comment

            #6
            oh right... I always forget to mention that thing may have a hole in it. disconnect the vacuum hose to it and hook up a vacuum pump to it (if you have one) and pull a vacuum. If it holds... it's fine... probably the check valve. If not... there's yer problem.

            Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
            rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
            Originally posted by gadget73
            ... and it should all work like magic and unicorns and stuff.
            Originally posted by dmccaig
            Overhead, some poor bastards are flying in airplanes.

            Comment

              #7
              I have a hand held vac pump. I worked at a Ford dealer as a tech for several years and have been a mechanic for as long as I can remember. I am hoping there will be time this weekend among the things the wife is gonna ask me to do to look at it.

              Comment

                #8
                So the vent settings will change based on the amount of acceleration, correct? Basically the harder you jab the gas, the more the vent settings change? With the Auto Climate in the 03+'s the defrost setting is default when there is a fault in the system. My guess is to at least be able to defrost your window even if you have a system failure.

                I went through all the same troubleshooting on my 03 CV Sport. It came down to the entire head unit was defective. Even the EATC self tests did not show this issue. If you open it up, you will see 4 vacuum canisters in there wired into the rest of the circuit board. The o-rings in these canisters are known to leak internally and cause this exact issue.

                If you go to Ford for the EATC unit, it will run you about $500, and it will be no better than the one you are pulling out.

                A better solution is to:

                A: replace the o-rings and re-use your existing EATC unit

                B: Find an 02 Explorer in the j-yard with EATC and use the vac. units out of it. They are an exact match size wise, you will just have to move 4 wires to match how your GM is wired up vs. the Exploder. I can explain this further if you need.

                Personally, I used option B and have not had an issue since then. This is a known issue with the EATC units, but Ford never recalled them. I think I still have the how-to's on replacing the o-rings if you want to give that a try.

                Jay
                These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.

                Comment

                  #9
                  I have not had the time to look into this other than the canister( box) is not leaking and held 20" vac for over 5 minutes.
                  I have seen the valves go bad in the EATC before from what I guess was soda of coffee getting in there but never seen the orings go band. Worth checking into if all else test good.
                  I will update when I get the time to check it out.

                  Comment

                    #10
                    Just google "2003 Ford EATC issue", it will come up with several other cars that have the same issue with the leaking vacuum solenoids. The F-Series trucks and Marauders also seem to share this.

                    Jay
                    These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.

                    Comment

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