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The Detailed E30 R-134a Conversion Thread/DIY

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  • S.J.1981
    replied
    Well, everything installed, took it to a professional to test for leaks, do vacuum etc.

    Machine was able to pull around 27-28 Hg, they suspected a leak, so they filled the system with Nitrogen and used a "sniffer" to check for leaks, none found. So they checked the system with UV light, since there was some in the system. Again none found, which was interesting.

    Nice and cold air now, but the low speed condenser fan is not kicking in. We pulled relays and tested them, they are fine, we applied 12v to the condenser fan plug and it ran. So i tested the condenser fan resistor using this blog:

    http://www.rtsauto.com/e30-aux-fan-r...ary-fan-types/

    Low speed does not kick in, and clearly audible relay clicking. High speed kicks in fine, as well as the relay. So tomorrow a new resistor will be installed, will chase the wiring for any signs of cracks/corrosion etc.

    Next week, the shop wants me to come in again to double check for leaks, we are all not happy with the low vacuum, but we could not find any leaks, could be the gauge or elevation or something else.

    One last item, i ordered the BMW high pressure valve adapter: 64-11-8-363-260

    It fits right on top of the R12 connection, no need to remove the internal valve, it just screws on and deep enough to allow the R134a quick connect to do its thing. It also clears the brace for the hood just fine. I could not find any dealerships selling this in Germany but one (Schmiedmann), so if you are having trouble finding a short HP R134a adaptor, this one fits and clears just fine, pricey though at 16 here locally.

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  • S.J.1981
    replied
    Has anyone tried the following adapters from BMW:

    64118363259
    64118363260

    Only one supplier in Germany and MAYBE able to get it, otherwise NLA and all th ebay/amazon ones do not fit.

    Is it also possible to use the new pipe from the IX/convertible models?

    64538391040

    That long extension maybe "thin" enough just to allow the hood brace to shut, otherwise everything is either NLA or incorrect length.

    Leave a comment:


  • jeffnhiscars
    replied
    I couldn't find a good pic on real oem but the blend door is controlled by the rotary temp dial to the left of the sliders. It sits between the heater core and evaporator and directs air through one, the other or divides it between both (hence the blend). When you're on max AC there's no water going through the heater core so it's moot and when you're on max heat you typically don't have your compressor running although if you do, you'll still get hot air AND the benefits of the ac's dehumidification (perfect in rainy climates in winter).

    The door also triggers the heater control valve as you begin to turn it clockwise so the dial acts as an on/off valve for water flow. It's the door that actually determines the air temp coming in.

    I'm sure crap can find its way in there or the cable can get sluggish. It in my case it was user error. I had replaced my evaporator and while there's a hole in the left side of the frame for the temp sensor, the fins themselves are not pierced so I Just shoved the sensor in and it punctured it way through the fins. Unfortunately, the probe is rather soft so instead of going straight in it curved off to one side, blocked the blend door and kept me from getting past about 2/3 on the dial. After a cold and uncomfortable winter (in NC) I pulled the sensor, used a similar diameter screwdriver to drive a straight new hole then reinstalled the probe and VOILA...heat !!

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  • Garemie
    replied
    Originally posted by Garemie View Post
    What are the blend doors? Can't find any info on that.
    Still not sure what these are.


    If you're talking the sliders for air flow then I've checked those. It just seems to me that by design air will always pass through the heater core so if the heater core isn't fully shut off then this is a problem.

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  • 325e '87
    replied
    I want to stress that the use of any figures from the performance of my refreshed a/c should not be assumed to be a proper baseline for anyone. My system keeps me comfortable in the hot and humid south, I run 1 or 2 fan speed, never any higher, and i use recirc rarely. I hate stale air.

    When ambient temps are in the upper 80’s I am perfectly content. I’m sure I didn’t do the best job charging the system and I don’t know if I overfilled it a bit or if its a little low on Freon. It works and that’s good enough for me.

    Leave a comment:


  • jeffnhiscars
    replied
    My comments are not specific to your posts but are general based on dozens and dozens of similar posts. I'm not sure how you can say blower speeds are a constant when there are 4 of them plus recirc but that absolutely matters. I can adjust the blower speed of my home AC and it re rates the entire system and virtually all new air handlers are variable speed.

    I recall getting in to other people's cars (when I did such things) and when I saw they had it on permanent recirc the air was always nasty. It's intended for short term use for rapid cool/heat and dehumidification (read any owners manual). Cars leak but are not typically sieves so without fresh air coming in it does make a difference...but of course it's your car :)

    If your gauging your system performance with that being the case then it kind of proves my point.

    You're supply air is the same temp as your return air so your cooling and recooling the same air over and over without ever introducing warmer outside air and at apparently highway speeds with the blower on high so of course it will be lower temp. I don't use recirc, turn my fan down to 2 within about 10 minutes cause it's getting too cold and am in town most of the time.

    I'll also add that the evaporator is only capable of transferring so many btus regardless of cfms. You can move more air through it which creates a perception of comfort which is why they say turning on a ceiling fan makes it FEEL 4 degrees cooler but it won't make it cooler than it's design limit.

    We can agree to disagree about which is best but blaming the planet I'm from seems kind of off topic ;)
    Last edited by jeffnhiscars; 08-02-2019, 12:25 PM.

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  • Garemie
    replied
    What are the blend doors? Can't find any info on that.

    Leave a comment:


  • jeffnhiscars
    replied
    Originally posted by Garemie View Post
    Are the heater core shut offs known to not fully close on these cars? It looks like no matter what the blower blows through the heater core even when running AC so maybe my valve is partially not closing?
    The blend doors can stick or get blocked by a bent temp probe (AMHIK)

    Leave a comment:


  • Garemie
    replied
    Are the heater core shut offs known to not fully close on these cars? It looks like no matter what the blower blows through the heater core even when running AC so maybe my valve is partially not closing?

    Leave a comment:


  • The Dark Side of Will
    replied
    Originally posted by jeffnhiscars View Post
    Again yes and no since it's apples and oranges. I don't recall anyone ever indicating their blower speed so we have no cfm data. A few other factors which IMO make absolute temp even less relevant are:

    humidity..you heat water to create vapor and when it condenses back to water it sheds btus in large amounts. Since that happens in your evaporator, your 40 which may be in Phoenix where's there's zero humidity to overcome , is not out performing my 53 in Florida where the humidity is 110%. Ask anyone in the hvac industry and they will tell you humidity is actually more critical to comfort than temperature.

    The colder you get the less efficient the system will move btus since there are fewer of them remaining. This is why heat pumps which are just AC in reverse have back up electric for when temps start dropping.

    Rpms plus speed over ground determine compressor speed and air flow through the condenser. I don't see many of those figures.

    You can't drive for long on recirc for long and stay comfortable so that scenario doesn't help over time

    Put 2 cars side by side and go for a ride with a pair of infrareds then you may get good comparative data, but going online and saying "mine is bigger than yours"...not so much :)
    :roll:

    I've already specified all of those variables to the required precision for this discussion.

    In my last comment I was quite obviously talking about E30 systems, so CFM is a constant across the two options because it's the blower speed that E30's run. Regardless, automotive AC systems are engineered to be effective. Since there are only so many ways to skin a cat, blower flow isn't going to vary much across the industry. Not even Rolls Royce runs 5000 CFM A/C blowers.

    We all know that older BMW systems do kind of suck at low speed and low engine RPM, but reading back a few posts, in fact, my third post above to which you directly responded, I specified highway speed to this incipient hypothetical situation. That gets vehicle speed, engine RPM and condenser airflow high enough to be effective. The exact number is irrelevant, because if the system sucks at 50 but kinda works at 80, we know it's screwed up; conversely, if it's not screwed up it'll work just fine at both speeds.

    I don't know what planet you're on with recirc being uncomfortable, but I run mine all the time. That's also why humidity isn't a continuous factor.
    Last edited by The Dark Side of Will; 08-02-2019, 05:35 AM.

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  • jeffnhiscars
    replied
    Again yes and no since it's apples and oranges. I don't recall anyone ever indicating their blower speed so we have no cfm data. A few other factors which IMO make absolute temp even less relevant are:

    humidity..you heat water to create vapor and when it condenses back to water it sheds btus in large amounts. Since that happens in your evaporator, your 40 which may be in Phoenix where's there's zero humidity to overcome , is not out performing my 53 in Florida where the humidity is 110%. Ask anyone in the hvac industry and they will tell you humidity is actually more critical to comfort than temperature.

    The colder you get the less efficient the system will move btus since there are fewer of them remaining. This is why heat pumps which are just AC in reverse have back up electric for when temps start dropping.

    Rpms plus speed over ground determine compressor speed and air flow through the condenser. I don't see many of those figures.

    You can't drive for long on recirc for long and stay comfortable so that scenario doesn't help over time

    Put 2 cars side by side and go for a ride with a pair of infrareds then you may get good comparative data, but going online and saying "mine is bigger than yours"...not so much :)
    Last edited by jeffnhiscars; 08-01-2019, 12:43 PM.

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  • The Dark Side of Will
    replied
    Originally posted by jeffnhiscars View Post
    Yes and no. Of course for a rapid cool down/dehumidification recirc helps a lot since youre continuously cooling the same air repeatedly and hopefully faster than the heat load can add btus (assuming everything is closed). This isn't a bad "bench test" for efficiency but you have to also consider how long it takes to get to whatever minimum temperature it's capable or reaching. The problem is, I've rarely if ever seen an infrared posting explain the variables present...ie humidity, flap position, moving or not, rpms, humidity and ambient temp. If your cooling 90 degree air with a 20 degree differential eventually you should reach the "absolute minimum" but It's still just a 20 degree differential. This will take longer and have a harder time maintaining comfort in real world driving.

    If you're driving in 90 degree weather with a 35 degree differential and 85% humidity but your absolute minimum is 53 (like my cabrio) you'll cool down faster (very fast in fact) and wind up turning down your fan and/or temp setting sooner since most people are quite happy somewhere between 68-74.

    Absolute minimum is great for theory and bragging rights but IMO is not an expression of overall performance.

    My2c
    If your evaporator is at 52 degrees and you push XYZ CFM of air through it for a 53 degree discharge, then you're not pulling as many BTUs out of the air as you would if the evaporator were at 40 degrees and you pushed the same CFM at the same ambient temperature through it.

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  • S.J.1981
    replied
    Finally mounted up everything, new condenser (parallel flow), new o-rings, all lines/pipe(s) removed and cleaned, new drier, pressure switch, compressor cleaned out, fresh oil, expansion valve etc.

    Plugged in the new vacuum pump and lines, barely held 10hg vacuum. Checked around and found the adaptor not sealing correctly on the high side. Then found out that there is no vacuum pulled by the pump from the low side. Turns out to be a faulty connector (the one you press to slide into the low side).

    No matter which R134a adapter i used on the R12 lines, it never sealed correctly.


    Decided to return the whole pump w/hoses back and get a refund, will go to a shop to have them find the correct adaptor and leak/vacuum test the system for me. If all is well, i have 900g of R134a, will let them fill the system as well.

    Leave a comment:


  • jeffnhiscars
    replied
    Originally posted by The Dark Side of Will View Post
    You *CAN* judge by absolute temps. That's why the "recirculate" function exists. The heat load from ambient air passing over the outside of the car, radiator air passing underneath the car and solar radiation through the windows is enough for the A/C to fight. Trying to get it to do all that *AND* cool down outside air is not a recipe for great results.
    Yes and no. Of course for a rapid cool down/dehumidification recirc helps a lot since youre continuously cooling the same air repeatedly and hopefully faster than the heat load can add btus (assuming everything is closed). This isn't a bad "bench test" for efficiency but you have to also consider how long it takes to get to whatever minimum temperature it's capable or reaching. The problem is, I've rarely if ever seen an infrared posting explain the variables present...ie humidity, flap position, moving or not, rpms, humidity and ambient temp. If your cooling 90 degree air with a 20 degree differential eventually you should reach the "absolute minimum" but It's still just a 20 degree differential. This will take longer and have a harder time maintaining comfort in real world driving.

    If you're driving in 90 degree weather with a 35 degree differential and 85% humidity but your absolute minimum is 53 (like my cabrio) you'll cool down faster (very fast in fact) and wind up turning down your fan and/or temp setting sooner since most people are quite happy somewhere between 68-74.

    Absolute minimum is great for theory and bragging rights but IMO is not an expression of overall performance.

    My2c

    Leave a comment:


  • The Dark Side of Will
    replied
    Originally posted by Garemie View Post
    I have 55-58 degree results and while it *eventually* cools the cab I personally consider this conversation a failure. Vent temps should be in the 40s consistently for a properly functioning setup.

    I am going to try a Sanden compressor next. Or something similar.
    Exactly. If 55 degree discharge temp is the best the system can do, something is wrong. For an R12 system, evaporator temperature in F and low side pressure in PSI are approximately equal. R-134 isn't far off that.

    Leave a comment:

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