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ECC Problem V70-XC70 1998

posted by  Nikolaj on  Sat Jun 28 21:18 CST 2008
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last visit: Mon Oct 28 14:41 CST 2013
[RELATED]

Hi All,

I have a '98 V70 N/A with the automatic climate control (ECC). Like so many others have described here before me, I experice the compressor going on/off on what I believe to be a too frequent basis - but only in some instances. Here are my observations:
- System will give cold air and reach and maintain setpoint within comfortable margins (perhaps I should mention here that I live in Denmark where temperatures rarely go beyond 85F). No blinking lights :-)
- Compressor will stay engaged if I set the temperature setting at minimum (blue/cold/max. load...)
- I usually set the system at 70F. Once cabin temperature has reached setpoint, compressor will kick in and out every 5 sec. or so (with noticeable load/unload of engine) :-(
- I had an A/C chap reading pressure at low pressure side of compressor and it corresponded to -2 to -4 deg. C (28 - 25 F) (sorry I can remember the pressure value). He added 250 grams (~0.55 lbs) of R134a to the system which didn't change the cycling of the compressor.

I guess you can say that it is a small problem, since I am able to get the temperature I want. However, I am just worried that something is wrong and that it may not be healthy for the compressor to kick in and out all the time.

What kind of cycling time of the compressor would you say is normal for at healthy system? Would the cycling time be dependent on the load (i.e. difference of outside temp/amount of sun and the cabin setpoint)?

I seem to recall having seen a write-up or manual of the logics of the EEC control system (may not have been on this site) but I can't find it now. If anyone can point me in direction of such a write-up, I would be most grateful.

Your input to the above will be much appreciated, Thank you!

Nikolaj








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    ECC Problem V70-XC70 1998

    posted by  KlausC on  Sun Jun 29 14:26 CST 2008
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    last visit: Fri Oct 24 10:15 CST 2014
    [RELATED]

    Your system is running properly.

    At idle, the compressor will cycle a lot. At about 2,000 rpm, it will operate most efficiently. This is also the speed where the temperature will be the lowest and where the AC system should be checked.
    Adding too much R134a will decrease the amount of expansion allowed and cause the system to run too warm.

    Most 1998+ models do not have evaporator leak problems, like the 850s. They do develop leaks in the receiver/dryer tank if there is a lot of salt during winter driving conditions - very prevelant here in the USA. This does not seem to be your problem.

    As for the drag on the idle when the compressor engages, check/clean the idle control module as it is not reacting fast enough to the speed change. This is common at low rpm while driving.

    Klaus
    --
    I still miss my 164








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      ECC Problem V70-XC70 1998

      posted by  Nikolaj on  Sun Jun 29 15:30 CST 2008
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Mon Oct 28 14:41 CST 2013
      [RELATED]

      Thank you Klaus,

      I have not really checked the EEC operation at higher rpm's after the part refill and pressure check, which was done at idle. I will do that asap. However, I am currently travelling in India - fortunately all A/C's I have come across here worked ;-) - but I will not be able to get my fingers on the car before next week.

      Discharge temp seemed in the area of 130 F after refill - is this excessive?

      I recently cleaned the idle air controller, and I have to say that I have always been impressed by how rock stable the idle is when A/C kicks in and out. It is while driving (in any rpm range) that the A/C load on engine is felt. Does this indicate another issue?

      Thanks again for your reply!

      Nikolaj







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        ECC Problem V70-XC70 1998

        posted by  KlausC on  Sun Jun 29 17:00 CST 2008
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        last visit: Fri Oct 24 10:15 CST 2014
        [RELATED]

        Eventhough we deal in pressure readings over here, your temperature readings seem to be normal.

        My daughter's 850 turbo, 1995, does what your car does. The drag on the engine is noticeable at speed but at idle is very good. I do not know the cause of the problem. We have an evaporator leak in the 850 and I am too cheap to fix it, so I just charge it up myself. The previous owner replaced the compressor with a different kind which might be one of its problems.

        Klaus
        --
        I still miss my 164








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          ECC Problem - V70-XC70 1998

          posted by  Nikolaj on  Mon Jun 30 05:33 CST 2008
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          last visit: Mon Oct 28 14:41 CST 2013
          [RELATED]

          Hmm... At least I'm not alone :-) I'll make sure to let you know if and when I (or more likely someone else) find the cause of this behaviour.

          I believe that the ECU gives signal to the idle air pump when the A/C kicks in and out at idle. Would the ECU give a signal at elevated rpm's as well?

          Maybe connected to the above, I also experience a slight "jerking" (sorry - I don't know exactly what to call the sensation but it feels like the engine can't deside whether to let in gas or not) when coasting at just above idle. Does your daughters do that as well?

          Maybe I just have worn mounts and everything that's going on in and around the engine is felt more strongly?

          Thanks again!
          Nikolaj







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            ECC Problem - V70-XC70 1998

            posted by  KlausC on  Mon Jun 30 06:39 CST 2008
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            last visit: Fri Oct 24 10:15 CST 2014
            [RELATED]

            It is also possible that your throttle body is dirty. Check all of the vacuum elbows around the intake manifold and under the fan shroud. One of them might be cracked and slightly leaking.

            You are correct, the ECU controls it all, but I doubt that the ECU is at fault.

            Klaus
            --
            I still miss my 164







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