355 - AC expansion valve | FerrariChat

355 AC expansion valve

Discussion in '348/355' started by Beetle, May 28, 2020.

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  1. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    Hello all.
    I'm going to recharge my aircon and have a new receiver dryer and thought I might change out the TX valve #65518600 while I'm at it. Is there an interchangeable item anyone knows about?. Or could I get away with giving it a good clean? Is there anything I should not clean the valve with is probably a better question.
    TIA
     
  2. Ferrarium

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    There is I saw it a while back, check part interchange thread also. Run a search out here I think it is bmw e30?

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  3. kenneyd

    kenneyd Formula 3
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    #3 kenneyd, May 28, 2020
    Last edited: May 28, 2020

    I can't imagine Ferrari made its own proprietary expansion valve. Are the Ferrari ones unobtainable or something?
    you might have good luck just matching it up with one from an auto parts store.
    As for cleaning it, you could probably use 90% isopropyl alcohol, and replace the o-ring on it and be fine. Don't use any products with oils or water.
    If you replace the dryer or accumulator whatever, be sure to add in a little bit of oil (you'll need to look up if it's pag 46 or 150 etc) Pull a good vacuum, and recharge.
    If you are able to find a cross-reference part number, be sure to post it in this thread
     
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  4. Ferrarium

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  5. Beetle

    Beetle Formula Junior

    Apr 10, 2013
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    Ummmmm heading states 355? Cheers though I will check that link out. It's a 96 5.2
     
  6. kenneyd

    kenneyd Formula 3
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    I know the pictures are not always accurate, but I just looked up a 65518600
    And it looks almost identical to the expansion valve that I recently replaced in my Saab 9-3 2004


    Here's another link, you may be able to match it up based on size.
    https://www.uacparts.com/Catalog/eCatalogIndex
     

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  7. Ferrarium

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    Well yes.... it does now. Pretty sure it did not sat that when I responded or I did not see it. No matter it looks promising and that the important thing!
     
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  8. johnk...

    johnk... F1 World Champ
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    Many parts for the 355 are Saab, Volvo, Porsche, Jag, Range Rover, Audi.....
     
  9. bayferrari

    bayferrari Karting
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    Not sure if this will fit a 355, but here's the part number of the one I used on my 91 348, Egelhof TCD2.Part # 320305S. exact fit .
     
  10. Ferrarium

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    348 and 355 have different expansion valves.
     
  11. m.stojanovic

    m.stojanovic F1 Rookie
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  12. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    I will get one and try. If it fits I will put in the sticky section
     
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  13. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    355 A/C TX VALVE ( Expansion valve)
    Alfa Romeo 145TS 146TS
    For the Aussie guys I purchased mine through Auto8. Wangaratta VIC.
    PtNo C22-5017. $113 AUD.
    Posted in the 355 interchangeable parts section also.
     
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  14. johnk...

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  15. m.stojanovic

    m.stojanovic F1 Rookie
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    As long as the expansion valve has the same size and arrangement of the ports it will work well in the 355. I don't think that, other than the ports, there is much difference (if any) between the various expansion valves as to how they operate. Of course, there is a difference in operation of the valves for R12 and R134.
     
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  16. johnk...

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    If by size you mean orifice size, then yes. The orifice in the valve is usually sized based on AC capacity. The wrong orifice size can result in inefficient cooling or compressor damage in the worst case.
     
  17. Beetle

    Beetle Formula Junior

    Apr 10, 2013
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    Being BMW or I call them BMTrouble You, those would be more expensive than a Ferrari TX valve hahahaha. l do agree that just because they look the same they may not operate the same. In saying that there are lots of Fiat and Alfa parts that work just fine in Ferrari at a 1/4 of the cost
     
  18. m.stojanovic

    m.stojanovic F1 Rookie
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    The orifice is variable and mainly adjusted (automatically) to prevent freezing of the evaporator. I think that the average size saloon cars all have similar size compressors and evaporators so I see no problem using an expansion valve in one car from another car if it is identical in size/shape and has identical pipe connection ports (the valves will probably be identical in all respects anyway). And if the car in which the valve (same but from another car) is installed has a bit smaller evaporator, the valve will just start reducing the variable orifice a bit earlier and a bit more but these differences will be very small. On the other hand, the "dynamic size" of the evaporator is varied greatly by the blower fan speed and the variable orifice is capable of adjusting itself to a wide range of these variations automatically.
     
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  19. johnk...

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    Not that simple. The TX valve is calibrated to deliver a certain amount of coolant flow based in the temperature and pressure of the coolant leaving the evaporator. These variables control how open the orifice is (% or wide open for example). If the orifice is the wrong size, the incorrect flow will be delivered for the evap exit conditions. This would lead to, at least, poor efficiency and at worse damage to the compressor. But if the systems are of similar size they should be ok. However, there is a good reason why there are zillions of different TX valves.
     
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  20. Beetle

    Beetle Formula Junior

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    The main reason for so many is the manufacturer likes the idea that you will keep buying from them at exuberant prices. Simplicity! They know the majority of people won't do the homework to find the same part in a more common cheaper vehicle.
     
  21. johnk...

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  22. Ferrarium

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    I think using the part with the right spec is a universal truth, not just this part. Can you tell from port sizes alone or is there some variable machanicals inside you can't determine easily?

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  23. johnk...

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    #23 johnk..., Jun 5, 2020
    Last edited: Jun 5, 2020
    AFAIK these block style TX valves are kind of like a fuel map. The orifice is sized based on the required cooling capacities and how they response to temperature an pressure may be differen as well depending on the degree of superheat the system is designed for. On commercial systems the TX valve may even have pressure adjustment to fine tune the superheat level.

    A simple explanation of superheat. Coolant entering the TXV is a saturated liquid, meaning it is all in the liquid state, a saturated liquid. After passing through the TXV the pressure drops. This may cause some of the coolant vaporize. (Open a propane tank for your back yard barbecue and ice cold propane gas come out as the liquid propane under pressure expands to atmospheric pressure. Keep you fingers away or instant frost bite.) The coolant is now in a mixed state, partial liquid, partial vapor. The % vapor is referred to as the quality. o% quality is all liquid, 100% is all vapor, a saturated vapor. At constant pressure the quality increases with rising temperature. Once the temperature reaches the saturated vapor temperature 100% quality is reached (100% vapor), further increases in temperature are referred to as superheat. At a given pressure, superheat is measured as degrees above the saturated vapor temperature. Obviously, as the cold liquid or liquid/vapor enters the evaporator the coolant boils and becomes vapor which is what cools the air. The function of the TXV is to insure that the vapor exiting the evaporator is in the superheated region which assures that there is no liquid coolant exiting the evaporator which would then enter the compressor.

    If the TXV orifuce it too large it may not be able to close sufficiently to insure the coolant exiting the evap is in the superheated region. Liquid coolant may enter the compressor may damage the compressor. On the other hand, if the TXV can not open sufficiently to limit the degree of superheat, then the flow of coolant vapor to the compressor, which also carries the lubricating oil, may be insufficient to lubricate the compressor, causing damage.

    Obviously, it;s also important to have the correct amount of coolant in the system as well which is why you need to know what the high and low side pressures should be for a given ambient temperature and coolant type.

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    Ultimately, the wrong sized TXV will change the degree of superheat at the exit of the evaporator. It's it just a little off, probably no damage but the efficiency of the AC system will be effected, or even result in icing of the evaporator.
     
  24. Beetle

    Beetle Formula Junior

    Apr 10, 2013
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    #24 Beetle, Jun 5, 2020
    Last edited: Jun 5, 2020
    I will let you know the outcome JohnK when I get the opportunity to charge it up. At the moment this may take a week or so with my current commitments at work and at home.
    I totally understand the concerns with interchangeable parts and want to know that it's fine as well. Happy to use my car as a test. I will be using Hychill -30 as a charge gas which is 30% of R134a. I have no doubt that people in the Ferrari World will be going WTF is he doing. I have very close mates that are involved in this industry and even they are keen to see the results. Stay tuned
     
  25. Ferrarium

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    It would seem a Mitutoyo digital vernier caliper could answer needed questions one the TXV is in hand. This does not seeds like a hard issue to determine resolution to, but it may take a few txv's to find it.
     

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