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Discussion in '348/355' started by carwhisperer, May 17, 2016.

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  1. carwhisperer

    carwhisperer Formula Junior

    Sep 29, 2014
    426
    Sacramento, CA
    Full Name:
    Brian
    #1 carwhisperer, May 17, 2016
    My 95 355 AC was blowing warm air. I figured I'd start by adding a can of 134a. I bought a cheap hose with gauge, jumpered the green and green black wires to the pressure switch to get the compressor to turn on, which it did, and added 12 oz. of freon. I was feeling the air at the duct while doing it and it wasn't getting noticeably cooler. I noticed that the fresh air door wasn't moving to the recirculate position. I removed the motor and found that it spins freely, so I assume the gears are broken inside. There is no problem with the square drive piece to the door itself, a common problem I understand. I wired the door in the recirculate position. Along the way I noticed that the large suction line was not really getting cool as I added freon. Also, I noticed that the high pressure lines were hot at the receiver drier and where they cross under the low side lines. I suspected that the evaporator fan was not running so I took the car for a drive on a 90 degree California afternoon. By the end of a 10 minute drive I was getting cool-ish air from the vents. When I got back I checked to see if, according to the gauge on my Walmart AC charge hose, the system would accept more refridgerant. It was slightly below the red so I added a little bit more. At that time I could feel the suction line get a little bit cold. Incidentally, when I started the gauge red zero and I could see it climb as I added refridgerant.

    My conclusions are that I should make sure my evaporator isn't blocked and that the fan is turning on, and that if that doesn't fix the problem I should evacuate the system, pull a vacuum and start over. What do you think? Also, is the evaporator in the front like a 348? Is it on the driver's side in front of the radiator?
    Brian
     
  2. blue90

    blue90 Formula Junior

    Dec 15, 2013
    339
    NJ
    Full Name:
    Dave
    #2 blue90, May 17, 2016
    If my AC was ever blowing warm the first thing I would do it vacate whatever was left in the system at the local shop. Next pull a vacuum and see if there are any leaks. Most of the time it leads to bad o ring wherever air gets in. Then you just can't add enough refrigerant to make the effort worth your time because pressure is too high from air in system and you waste refrigerant starting over again. I would run dye in it and check all the fittings to getany leaks fixed, but there are refrigerant with sealer that can help small leaks seal.
     
  3. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,224
    Mount Isa, Australia
    Full Name:
    Pap
    #3 PAP 348, May 18, 2016
    Sounds like you had a major leak there if there was nothing in the system. You probably should have had it fixed properly while there was no freon in the system.

    But it's all good now, you have freon in the system so add a little more to make the suction side pipe VERY cold, to the point that it starts to 'sweat' water off it.

    Do this now and wait and see how long it lasts. You still need more freon in the system, but it might already be leaking out also.

    Next time have it fixed properly. Have a specialist look for a leak, fix it, fit a new drier then vac it down and charge it. You need to vac the system every time to remove all the moisture inside the a/c system and to allow the full maximum charge into the a/c system.

    Don't worry about the blocked evaporator, if you have good airflow from the a/c vent then that is ok.

    Definitely make sure the condenser fan is working though. That should come on as soon as turn the a/c on.

    I service and repair a/c systems a few times a week. If you need to know anything else just ask Brian.
     
  4. LorenzoR

    LorenzoR F1 Rookie
    Rossa Subscribed

    Sep 26, 2015
    3,199
    Sarasota Fl/Pittsburgh
    #4 LorenzoR, May 18, 2016
    In my case the heat was always on to. So I noticed the stepper motor wasn't turning. It turned out to be the ac ecu wasn't sending the stepper motor the signal to turn one way or the other. Not sure if this is your problem but its easy enough to check. Remove the trunk lining and turn your climate control back and forth to heat then ac and see if it moves. If it doesn't move and its stuck in the open position you will get constant heat.
     
  5. F355Bob

    F355Bob Formula 3

    Nov 4, 2003
    2,001
    Madison, Wisconsin
    #5 F355Bob, May 18, 2016
    If does not turn you can pinch the hose going into the motor with a vise grip and you should have cold air. Are you getting air out of your center vents?
     
  6. carwhisperer

    carwhisperer Formula Junior

    Sep 29, 2014
    426
    Sacramento, CA
    Full Name:
    Brian
    #6 carwhisperer, May 18, 2016
    Yes I'm getting air out of the center vents. I couldn't remember which way is closed for the coolant flow valve but the hose on one side seemed noticeably cooler than the hose on the other side of that valve so I assumed it was closed all the way or close to it. I also found that the evaporator fan isn't turning and that I'm getting power to it. I think there is a problem where the fan attaches to the shaft. I plan to remove the fan assembly tomorrow so I can get a look at it. I also tend to think I've got air in the system. When driving on the freeway the air got cooler but not as cold as it should be. I plan to look for and fix any leaks, pull a vacuum and recharge. I need to get up to my cabin to get the equipment. Where are ll the joints? Can they be seen with the trunk liner out and the belly pan off without any further disassembly?
     

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