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940 AC 900 1992

posted by  someone claiming to be Chris K on  Thu Jul 31 09:18 CST 2008 [RELATED]

My AC runs for 5-10 mins and blows fuse. The vent outlet selector position wasn't working either, as air was partially blowing from every vent(defrost, dash, floor). Replaced the AC Control unit for $200.(non-returnable) thinkling what else could it be? Still blowing fuse and outlet selector knob still doesn't do anything. I keep looking at my sledgehammer in the corner of the garage, but it's my daughter's car! Help.








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    940 AC 900 1992

    posted by  someone claiming to be Chris K on  Sat Aug 2 01:02 CST 2008 [RELATED]

    Anybody have any thoughts on why I keep blowing the climate control fuse and the vent selector knob(defrost/face/floor) does not work after replacing the $200 climate control box??? Thanks for anyone's help.








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      940 AC 900 1992

      posted by  HillBilly on  Sat Aug 2 03:44 CST 2008
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      last visit: Thu Oct 16 08:26 CST 2014
      [RELATED]

      Try selecting a heat setting on the control so that the A/C compressor clutch doesn't engage and see if the fuse blows.
      This way, the only big load on the system will be the blower motor.

      That fuse (#16) should be 30 amps.

      Does the blower motor make any (un-usual) noise when it's running?

      The only real load on fuse 16 is the Blower motor and the A/C compressor clutch, although it does power up the MCC and ECC modules.

      So....if it's blowing a 30A fuse, I'd suspect a shorted A/C clutch or defective blower motor.....unless you have a wire short-circuited somewhere.

      steve








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        940 AC 900 1992

        posted by  someone claiming to be Chris K on  Sun Aug 3 02:02 CST 2008 [RELATED]

        Steve,
        Blower fan runs fine for extended period of time. No funny noises or anything. AC does make a lot of noise when turned on, and #16 fuse continues to blow after 5-10 mins. But what would an AC clutch(assuming that's the issue) have to do with the vent selector not directing air? It's mostly coming out the floor vent.








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          940 AC 900 1992

          posted by  spook on  Sun Aug 3 04:07 CST 2008
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          last visit: Fri Oct 24 08:06 CST 2014
          [RELATED]

          Dear ChrisK,

          May this find you well. Vacuum allows vents' positions to be changed. At the back of the climate control unit (CCU), there is a multi-hose connector. Through this connector, the selector knob shifts vacuum from one set of "doors" to the other, causing air to flow in the chosen direction. I do not recall reading many posts, about this system causing problems on 940 series cars. On 960 series cars, by contrast, I've read many reports of failure of the rubber bellows ("motors") that convert vacuum into "door" movement.

          It could be that because a leak, or because the connector has come loose, that there's inadequate vacuum: just enough to move "doors" to a mid-way position. I do not know if a "no vacuum" condition causes doors to default to "open" or "closed". I'd guess it is "open", as some air flowing everywhere is safer than no air flowing anywhere. That is, one will have some de-frost capacity, if there's inadequate vacuum, rather than none at all.

          I'd check the vacuum connector at the back of the control unit. If that is fully-seated, and not cracked, etc., then I'd check to see if the vacuum supply is adequate. When the engine is running, there should be suction at the multi-hose connector, that fits onto the climate control unit. If there's no suction, start at the vacuum tank, which is next to the blower motor. I believe that is the entry point for a hose from the engine. On the parts diagram, this is not entirely clear. I've never had to go into that area: I'm sure someone, who has, can describe more fully the vacuum hose routing.

          Hope this helps, at least a little.

          Yours faithfully,

          spook








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            here is a picture of the reverse side of the unit 900 1992

            posted by  trichard on  Sun Aug 3 04:26 CST 2008
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            last visit: Fri Oct 24 05:52 CST 2014
            [RELATED]

            i recently had to re solder my daughter unit so it would work.
            if you look at this picture the upper most left pin and lower most right pin are solid. the rest are tubes from which vaccum controls the vents. the soft rubber one piece unit slides in sticky rubber way over the pin. if this piece was not inserted correctly or some pins did not have tubes on them you will not get venting. it is pretty dirt simple once you see how it affixes.

            the eaisest way to deal with it if it is not on right is to remove the mcc unit. there is good documentation on the 700 faq section. i am afraid there really is no other way to get at this than to plan on doing what it take to remove the whole unit. although IF it was partially attached you won't have to remove the whole unit just gain access to the back which requires the same spade work. you may find this piece was not inserted onto the pins at all or partially fell off.

            i found the easiest way to get viewing and access is to take off the left side leg bolster on the passenger side which shields the middle console from the occupants legs. you may also find the radio is in the way and needs to come partially out as well. sorry to bring bad news but none of this really hard to do and once you do it you can dismantle it to gain access in 15 minutes. no fooling

            IF there are hole in the tubing from the the one piece rubber end to the various venting systems your best best is to get a mityvac and test each line off this one piece unit for holding vacuum.







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              here is a picture of the reverse side of the unit 900 1992

              posted by  someone claiming to be Chris K on  Sun Aug 3 10:26 CST 2008 [RELATED]

              Thanks! I did find a vacuum hose dangling under the hood, so it must have come loose and pulled out. I can't figure where it connects on the engine, as the entire tube came out in my hand when I was tracing it. So that connects somewhere on the motor and goes thru the firewall and connects on the back of the MCC unit pictured? Looks like one of those very tedious jobs I never look forward to! Thanks again to you and Spook for your input.








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                here is a picture of the reverse side of the unit 900 1992

                posted by  spook on  Sun Aug 3 11:12 CST 2008
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                last visit: Fri Oct 24 08:06 CST 2014
                [RELATED]

                Dear ChrisK,

                May this find you well. If there's a vacuum hose missing, the first thing to do is to find out where it goes. I'd do that, before trying to inspect the back of the Climate Control Unit (CCU).

                On what side of the engine were you, when the hose came loose? How long is the hose? What diameter is it (inside and outside)? I presume it is black. Is it cracked or torn at either end?

                Can you see any opening in the firewall, on the passenger side of the engine, that is large enough to accept the hose, that came loose?

                The vacuum reservoir is on the passenger side of the engine bay. The most likely source of the vacuum, used to supply the reservoir, is the intake manifold. Look at the manifold, with a view to seeing if there is a nipple, onto which the hose will fit. If the hose came loose recently, the nipple should be relatively clean. It is probably made of brass.

                Hope this helps.

                Yours faithfully,

                Spook








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                i would if i were you 900 1992

                posted by  trichard on  Sun Aug 3 10:38 CST 2008
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                last visit: Fri Oct 24 05:52 CST 2014
                [RELATED]

                start by removing the glove box and then the shield where your passengers legs touch that hides the guts of the center console. i think with a strong light you should be able to ascertain if the vacuum hoses are attached.

                the radio may or may not have to be pulled out a bit as well.








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        940 AC 900 1992

        posted by  someone claiming to be Chris K on  Sat Aug 2 05:49 CST 2008 [RELATED]

        Thanks Steve. I'll try the heat with the fan on high and see what happens, but the heater fan has its own fuse(#6) which never blows. #16 is labeled "Climate Control ECC/Heater Fan/Air Cond MCC" . I'm still baffled why the Vent control knob (defrost/face/floor) isn't working.








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    940 AC 900 1992

    posted by  someone claiming to be Chris K on  Fri Aug 1 02:00 CST 2008 [RELATED]

    Steve: The #16 fuse which controls the climate control system. I'm wondering if there's a wire on the blower or AC compressor that's shorting?







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