Very tricky 308 A/C problem, need help! | FerrariChat
Buy

Very tricky 308 A/C problem, need help!

Discussion in 'Technical Q&A' started by scotttgold, Sep 12, 2004.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. scotttgold

    scotttgold Rookie

    Aug 24, 2004
    8
    #1 scotttgold, Sep 12, 2004
    Lets see if you guys can solve this one.
    Car: 1982 308 GTSi
    Problem: The A/C does not blow cold and normal unless at Highway speeds or high rpms. When at idle it only blows the ambient air temp. But get this,... occasionally the system will work just fine and function fine at idle and highway speeds.
    So I checked some things.
    The blower works fine, the fans work fine. I can hear the compressor cycle like it should, (click on and off and watch the rpms slightly change).
    So I thought I just need an A/C recharge and leak test. So I had it tested and recharged. Full recharge, no leaks and pressure is fine. I guess it decided to blow cold for the technicians but by the time I got home it was blowing warm again at idle.

    This is driving me crazy. How could it work only at high rpms sometime but then, once in a while work just fine even at idle?

    Expert advice needed badly.

    Thanks for the help.
    Scott
     
  2. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,067
    Kansas
    Full Name:
    Sean F
    #2 Sean F., Sep 12, 2004
    Bad expansion Valve or maybe your contacts are dirty on the switch inside the car. Also check the contacts at the compressor and be sure they are clean.
     
  3. ria

    ria Formula Junior

    Nov 2, 2003
    732
    ohio
    Full Name:
    phill
    #3 ria, Sep 12, 2004
    if you have no leaks then make sure the clutch it is not sliping oil on clutch clutch goin?
     
  4. yank05

    yank05 Formula Junior

    Nov 8, 2003
    272
    New England
    Full Name:
    Anthony
    #4 yank05, Sep 12, 2004
    Hi Scott,

    Intermittent cooling air can be due to a number of reasons:

    1. Your evaporator could be clogged - inspect the fins. It may be icing up during operation.

    2. When you had it rechagred, was the system evacuated for moisture or was refrigerant just added? If you have excessive moisture in the system it may be freezing and causing a blockage (or restriction in system)

    3. You may have a bad thermostat switch causing the compressor to operate for too long of a period, causing the evap to freeze up....

    4. Bad expansion valve may be the culprit too as Sean indicated

    Best thing to do is to hook up a manifold test gauge set and note the readings - if low and high side readings are normal, it may be the thermostat or moisture in the system. If the high side is normal and low side is normal, then low side moves to indicate a vacuum, you have moisture which is freezing and causing a blockage....

    Good Luck,

    Anthony
     
  5. scotttgold

    scotttgold Rookie

    Aug 24, 2004
    8
    #5 scotttgold, Sep 13, 2004
    I have to rule out anything freezing up. It never has and isn't doing that currently. It really makes me wonder what component is failing. What could only work or function at high rpms and then not work with low rpms? And to make it worse, what could make this component work just fine sometimes at both high and low rpms. What in this system

    Any other takers?

    Thank you for your replys,

    Scott
     
  6. maurice70

    maurice70 F1 Rookie

    Jan 25, 2004
    4,334
    Sydney
    Full Name:
    maurice T
    #6 maurice70, Sep 13, 2004
    Besides the other things pointed out Im also tipping that the clutch is not engaging all the time but also what is the condition of the condenser?If it is dirty or blocked or the fins are all bent then at idle your condensing temps are to high but travelling at a certain speed the air flow might just be enough to make the difference.How are the condenser fans?Are they coming on at idle?Does your car have any other restrictions at the front grill,ie number plates air horns or any other restrictions?
     
  7. scotttgold

    scotttgold Rookie

    Aug 24, 2004
    8
    #7 scotttgold, Sep 14, 2004
    When the A/C is turned on the rpms will change slightly. I cannot remember if they go higher or lower but they do change. To me this means that the clutch is engaging. Is this wrong? When the A/C blows cold or hot the compressor always seems to operate the same. So I'm guessing the clutch is ok.

    I have done numerous cold and hot touch tests on the many lines in the system. I have notice that when the system is not operating properly that the line from the compressor to the condenser is still hot just like when the system operates normally. This makes me think that the compressor is doing its job. Right, wrong? What do you guys think? What else could cause this intermittent problem?

    Thanks,

    Scott
     
  8. scotttgold

    scotttgold Rookie

    Aug 24, 2004
    8
    #8 scotttgold, Sep 14, 2004
    Sorry I forgot to answer your questions. The condenser looks perfect. Not a bug on it. And the fins look perfect. And there is nothing blocking the fans or wind.

    Thanks

    Scott
     

Share This Page