AC issue

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Thread: AC issue

  1. #1
    SupraForums Member whitetiger777's Avatar
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    AC issue

    So, haven't had this issue before with AC. When I turn on the AC it blow cold and will do so for an amount of time. It's different every time. Then it goes warm. It doesn't matter if I'm stuck in traffic or doing 70 mph. Given that the air will go warm even if the car is moving at speed, im guessing it's not the compressor but am open to opinions

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    SupraForums Member supralover93's Avatar
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    expansion valve is sticking?
    §§
    93 turbo targa
    auto
    BPU

  4. #3
    SupraForums Member whitetiger777's Avatar
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    How does once check that?

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    SupraForums Member supralover93's Avatar
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    thats something an AC tech would have to check with a set of gauges. chances are you will have to take it in to get proper diag work done. even if the expansion valve is bad, you would have to evac. the system before making the repair (which is NEVER fun).

  7. #5
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    How cold is it when it first works? Ice cold or just cool. AC's are funny in that they can be just a bit low and not work well at all.

    You can buy a cheapy gauge that has both high and low side fitting where you can check pressures on each side. You should be able to use a quick reference guide to estimate where your pressures should for the ambient temp with the compressor running (it will be obvious if it isn't as pressure will be the same).

    When I first got my Supra a year ago after a month my AC started going from cool to ambient while driving. My high side pressure I believe was around 150 psi. I added about a 1/2 can of R134A and the pressure came up to about 200ish (was a 90+ degree day) and now is ice cold. Been that way for about 9 months.

    You could alsways buy a small can and just add in a bit (2 oz) of refrigerant and see if that helps. If you are low that little bit of refrigerant would make an exponential difference.

  8. #6
    I Can Has EBT? shak's Avatar
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    x2 on expansion valve. I had mine go out years ago, but I remember the same symptoms you are describing.

    thread on how to replace, but you will need someone to recycle freon for you, and cycle it back tot he system when you are done.
    https://www.supraforums.com/forum/sh...xpansion-Valve
    Last edited by shak; 03-13-2019 at 06:49 AM.

  9. #7
    SupraForums Member whitetiger777's Avatar
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    Doesn't seem that hard aside from vac'ing the system

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    i would try adding a can of 134 first... to see if it fixed it.
    if it does,... then you have a slow leak.

    but im with the other guys... looking like an expansion valve.

  11. #9
    SupraForums Member whitetiger777's Avatar
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    Will check the pressure this weekend

  12. #10
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    I would not recommend adding refrigerant to the system. If there isn't a leak and the correct amount of R134-A is still in the system, an over-pressure situation could occur causing damage to the compressor. If the compressor goes, then you can also say goodbye to the condenser and the lines. I recommend evacuating the system, refilling with 24.5 oz of R-134A and UV dye, then performing a diagnosis. Part of the diagnostic process prior to recharging involves pulling a vacuum on the system for 24 hours to see if it holds. This will help narrow down the presence of a leak. Recharge with R-134 that does not have any sort of fix-a-leak or sealant in it. Run the system for an hour then check for leaks using a UV light. Remember to look under the dash, around component input/outputs, and at the recharge/discharge valves. Verify the correct pressure indications on the H/L side using the gauges and the FSM. Without using the process described above, you are guessing, which can be an expensive gamble. If you are willing to gamble on a guess, it does sound like the expansion valve went south. You can't hurt anything by replacing it and the corresponding O-rings, and recharging with R-134 and the UV dye. The benefit is, you will have eliminated a common culprit, and made future troubleshooting easier. I'd also recommend replacing the receiver/drier and it's corresponding O-rings when you open the system. You will likely have repaired your issue using this process. If not, you are way farther along in the troubleshooting process and already have to two most common AC wear parts replacement enroute to the repair that fixes it. Good luck, and PM me with your email if you would like any pictures. I did this entire process last year when I repaired a leak in the AC hard lines. Thanks! -Tony

  13. #11
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    For what its worth, I chased down a similar issue. After going through steps like listed above, I still had the problem. What I ended up finding with my system, is the wiring harness that connects to the controls was full of shorts. A new plug and a wiring harness repair kit solved my issue.

  14. #12
    SupraForums Member whitetiger777's Avatar
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    I was starting to wonder if it was an electrical thing

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    MarkH brings up a very good point. The stuff I mentioned only addresses the refrigerant part of the system. There is also the mechanical and electrical part, each requiring an investigation. A good check of all the components will help you save some $ and time in the end. Good luck and let us know how it goes!

  16. #14
    SupraForums Member whitetiger777's Avatar
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    Think I might just take it to a ac place to have it checked

  17. #15
    SupraForums Member whitetiger777's Avatar
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    Took the car to a ac shop and the pressure on the high side was the same as the low side, so it must be the expansions valve.

    Wish there was a video or picture step by step for this. System is already vac'ed out.

  18. #16
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    Here's a general outline:
    1. In engine compartment, remove 10mm bolt securing a/c lines to firewall.
    2. Drop glove box, and supporting brackets behind it.
    3. In accordance with FSM, disconnect harnesses, plugs, and remove fasteners that secure the evaporator core to heater box.
    4. Manuever evaporator core down and out of heater box.
    5. Unbolt expansion valve from evaporator core.
    6. Replace all o-rings on opened a/c lines. Should be two for the a/c lines in the engine compartment, and four on the expansion valve. Lubricate the o-rings with some u/v dye.
    7. Clean evaporator core and condensation pan of debris, leaves, 20 years worth of crud, etc.
    8. Reinstall is reverse of previous. If required, add compressor oil per FSM. You might not need to when just replacing the expansion valve, but chaning out condenser, drier, compressor, and other large components require that you add a certain amount to replenish what's lost.
    9. Recommend (required actually) replacing receiver/drier and associated o-rings at this time. It's 20 years old+, and the desiccant is no longer effective. The system has been opened and that drier can't absorb moisture it's now exposed to. Your compressor will in the form of failure. Be sure to add the right amount of compressor oil per the TSM.
    10. Recharge with 24.5 oz of R-134a and and couple ounces of u/v dye.

    A note on the compressor oil.. ND-8 is what is called for but good luck finding it in small quantities. You can find an equivalent at parts stores; but it's synthetic unlike good ole ND-8.

    If you'd like pictures, I can email you a few that might help with disassembly. Just PM me. Good luck! -Tony

  19. #17
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    Vtony 100% right! Although, I prefer not putting any dye in. I've seen this on a few MKIVs. New expansion valve, along with all mentioned above, solves the issue.

    Don't see it mentioned but is implied, vacuum the system for 45 minutes minimum through gauges, close off high and low side valves and watch for 10 minutes for loss of vacuum. Hook a can to the center line and unthread at the gauge side and allow a little r134 gas to purge the line of any air (moisture). I always just turn the 1st can over and allow the liquid into the vacuumed system before starting the engine. After a couple of minutes I'll start it up and turn on the a/c, let it pull down as low as it'll go on the low side and close the valve and hook up another can. I've never had an issue with turning the can over and slowly letting in liquid r134. I just barely crack the low side valve just enough so the needle starts to jump slightly and let it dribble in for 5 minutes or so. It's always takes forever letting it boil off from the can.

    ND-8 is equivalent to PAG 46.

    compressor-oil-1_614x307.jpg
    Last edited by Kurt; Yesterday at 09:33 PM.
    1997 GE VVTi 6spd

  20. #18
    SupraForums Member whitetiger777's Avatar
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    I'll probably go with the pag oil since it's easier to find

    I'm definately interested in those pics that were offered

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