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A/C and the Radiator Fan Switch

Discussion in '308/328' started by SoCal308GTSiQV, Jul 5, 2009.

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  1. SoCal308GTSiQV

    SoCal308GTSiQV Formula Junior

    Nov 3, 2008
    585
    Ojai, Ca.
    Full Name:
    Chris
    #1 SoCal308GTSiQV, Jul 5, 2009
    Last year at the end of the summer driving season my fan switch on the radiator that turns the radiator fans on and off went bad. As it was the end of the season and I was about to put the car away for winter, I just pulled the wires, jumped them together to run the fans all the time. I figured this summer I would get a new switch, which I have just done.

    At the end of last year I also noticed that my Air Conditioning was not blowing cold. The system was just serviced a little over two years ago, replacing the compressor and recharging with R12. The system worked well (as well as can be anyway!)

    I have spent the better half of the winter reading A/C threads preparing myself for the nightmare ahead. Reading everyone else’s experiences trying to get this darn A/C system to work. I even read the thread where the guy has the whole interior out and thinking this may be my future!

    I prepared myself for the cost of either a recharge with R12, a complete conversion to R134a or saying **** it all and replacing the system at great cost to something from Honda!

    But, as it turned out my Dad had a few cans of R12 kicking around so I figured I’d just try filling the system one more time on my own, just in case I had a leak. I figured this would give me at least one more summer before the nightmare would have to be dealt with.

    Unfortunately I do not have a pressure gauge to read the A/C system and after watching enough you tube video’s, reading threads and A/C websites that say “This thing can explode and KILL YOU!” I decided I would wait until I bought a gauge to mess with it.

    But one thing I saw on a video on you tube said that if your compressor is turning on and off that probably means you need a fill. So I went out, pulled the rear tire, pulled the inner wheel well and fired the car up to see if the compressor clutch was even engaging at all let alone turning on and off.

    Here’s the interesting part of the story….

    The Compressor clutch was indeed engaging and it was not turning on and off so I jumped in the car and it was blowing cold!

    With the car sitting still on stands, the A/C was blowing ICE cold just as it did last summer!

    So the question is, how is the radiator fan switch integrated into the A/C system? Does a properly operating radiator fan switch tell the A/C when to turn on and off? OR I’m I just out of my F’n mind?

    Also, I'd like to give a shout out to Superperformance for getting me my switch out to California in less than 5 working days! They ROCK!
     
  2. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    #2 Paul_308, Jul 5, 2009
    There are 3 relays which control the two radiator fans, circuitry being the same for all 308 cars. The radiator thermal switch controls right and left fans through right and left relays. And that's all they switch. The AC switch turns on a third relay whose contacts parallels the right fan, so it will come on even if the radiator thermal switch isn't indicating a hot condition. Restated, the AC and radiator fan switch are independent of each other. Your shorting or grounding the thermostat switch will not affect the AC.

    When the AC switch sends 12v to the coil of the third relay, that same 12v also is sent to the AC max and min pressure switches, and from there to the AC clutch. Incidentally, the wiring diagrams with this info are at http://www.ferrari308gtbi.com/ Probably what has happened is the min pressure switch is at edge of operation. It's unlikely that the max switch is causing problems. Try adding a smitgen of R12 and see if the clutch doesn't now operate when driving. If so, add a bit more. I got my gauges at Harbour Freight, but know that the R12 fittings are different than F134A for good reason, so be sure all fittings are included.
     
  3. SoCal308GTSiQV

    SoCal308GTSiQV Formula Junior

    Nov 3, 2008
    585
    Ojai, Ca.
    Full Name:
    Chris
    #3 SoCal308GTSiQV, Jul 5, 2009
    Thanks for the reply, so your thinking that I'm still am a bit low on R12. If so thats an easy fix, I just need gauges. I'll look into getting some and test the pressure to see if it's low or on the edge of being low.
     
  4. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,367
    NY
    #4 Steve King, Jul 6, 2009
    1st go to the front and remove the cover under the bonnet. You will see the receiver/dryer next the the brake fluid , on the passenger side. On top of this black can is a "sight glass" . With the system on and running look into the sight glass and see if there are bubbles. If you see a stream of bubbles then the system is low on freon 12. Note: this is for R12 systems only becayse R134a will have bubbles. If you have bubbles then charge until the bubbles are gone. The system will then be filled. Make sure that you charge from the low pressure side (suction) of the compressor. Make sure you wear safety glasses. Freon can freeze your hands or eyes if not handled correctly. Just a precaution.
     
  5. SoCal308GTSiQV

    SoCal308GTSiQV Formula Junior

    Nov 3, 2008
    585
    Ojai, Ca.
    Full Name:
    Chris
    #5 SoCal308GTSiQV, Jul 6, 2009
    I was wondering where the sight glass was. Thanks for the info.
     

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