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348 AC issues

Discussion in '348/355' started by Tom_C, Jun 1, 2008.

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  1. Tom_C

    Tom_C Karting

    Feb 20, 2008
    233
    Raleigh area, NC
    Full Name:
    Tom C
    #1 Tom_C, Jun 1, 2008
    AC not working. Control unit seems fine, as all functions as should, although I haven't checked the recirc flap yet, as I understand that it won't prevent the ac from operating. When I pressed on the low pressure valve, I got a weak hiss that went to no hiss in about 5 seconds. That lead me to believe that there was low to no pressure. Car has been converted to 134a, so I headed down to the local Advance Auto and picked up the $30 recharge kit. Put the kit on, and put a bit into the system, and I swear I heard the compressor come on. Compressor went back off (assuming it was the compressor) and would not come on again. I ended up with about 30# on the low pressure side, with no indication that the compressor was working, or the dryer fan? (fan in right wheel well) was coming on. Pulled the pressure switch, and there are 4 wires going to it. Chacking the unit itself, I got pins one and two with some resistance, and three and four with none (arbitrary numbers, cant remember the colors right now) My understanding is two of the wires are high pressure switch, and two are low. Jumped one and two, and the fan in the right wheel well came on. Jumped three and four, and nothing (assuming they were the high pressure, so nothing would happen anyway) When fan cut on, I still never heard anything from the compressor. I haven't checked the voltage to the compressor yet, but was wondering what else it could be. I am assuming that if everything is on, I will have voltage to the compressor, and if the compressor is not working, its a compressor issue. If no voltage, then it's either the pressure switch, or my system pressure is incorrect, and I will need to carry it to someone with the proper gauges to check everything out. Am I on the right track? I'll be posting this in the Technical section as well, just for more traffic. TIA!
     
  2. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,224
    Mount Isa, Australia
    Full Name:
    Pap
    #2 PAP 348, Jun 1, 2008
    Put some gauges on it first Tom and go from there. You seem to be on the right track. :):)

    Knowing what a/c pressures you have is a MUST in diagnosing any a/c fault. :):)
     
  3. Ferrari328GT

    Ferrari328GT Karting

    Jan 6, 2008
    232
    Phoenix, Arizona
    Full Name:
    Steve
    #3 Ferrari328GT, Jun 1, 2008
    Yep, +1. -Steve
     
  4. Ferrari328GT

    Ferrari328GT Karting

    Jan 6, 2008
    232
    Phoenix, Arizona
    Full Name:
    Steve
    #4 Ferrari328GT, Jun 2, 2008
    Hello Tom. I have a little more time now to answer your question. I think you are exactly on track. But you really need to have gauges hooked up to the low and high side before proceeding. If it's something you're really interested in, gauges are relatively cheap, and will pay for themselves almost instantly. Once you have gauges hooked up, you could even run 12v straight to the compressor and see if you get cold air. The reason you need gauges is to make sure the high side doesn't get too high while you are diagnosing other parts. You really don't want to start blowing hoses or lose refrigerant out the blowoff valve. Assuming the compressor runs, you can then bypass each sensor, one at a time, and narrow down the problem. Let me know how I can help. -Steve
     
  5. Tom_C

    Tom_C Karting

    Feb 20, 2008
    233
    Raleigh area, NC
    Full Name:
    Tom C
    #5 Tom_C, Jun 2, 2008
    Thanks guys. I guess I need to invest in a set of gauges.... :)
     
  6. Tom_C

    Tom_C Karting

    Feb 20, 2008
    233
    Raleigh area, NC
    Full Name:
    Tom C
    #6 Tom_C, Jun 5, 2008
    Update... The compressor will not work if the wire is not plugged into it... The tech that did the major before I bought the car never plugged the wire back in....
    So now, I hit the AC button, and I hear the compressor click. I'm not sure it is staying engaged, as the rpms don't really go down, and when I cut the AC back off, I don't hear it stop. Also, is the fan at the front (condensor fan?) supposed to come on at the same time as the compressor, when the AC button is pressed? Mine's not. I know I still need to go and get gauges to see the pressure, but figured I'd let everyone know that the wire has to be plugged it for stuff to work..........

    As of today I have officially spent more time under the car than in it....
     
  7. FandLcars

    FandLcars F1 Rookie

    Aug 6, 2006
    3,057
    Tempe, Az
    Full Name:
    Rick Schumm
    #7 FandLcars, Jun 5, 2008
    Ha Ha... After spending about an hour in my 348 after taking delivery, I immediately removed the subframe, and am in the middle of a major inspection ;) I"m looking for the payoff after I get it done, though!! I think we do need to get used to spending time under, over, and around them, rather than just in them :)
     
  8. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,201
    socal
    #8 fatbillybob, Jun 5, 2008
    I'm real leary of conversion to 134 from r12. Often improper conversion is done and the oils are not compatible and extreemly difficult to remove. So the oils collide and bad things happen that are more expensive than if you just stuck with r12. Oh and A/c work without guages is like working on your car with a hammer and cresent wrench
     
  9. Tom_C

    Tom_C Karting

    Feb 20, 2008
    233
    Raleigh area, NC
    Full Name:
    Tom C
    #9 Tom_C, Jun 6, 2008
    Crescent wrench worked fine on my old vette.... ;) :D
     

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