Mondial QV Blows cold then hot. | FerrariChat

Mondial QV Blows cold then hot.

Discussion in 'Mondial' started by Anthony bentley, Jun 26, 2018.

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  1. Anthony bentley

    Anthony bentley Formula Junior

    May 20, 2006
    540
    London
    Full Name:
    Anthony Bentley
    #1 Anthony bentley, Jun 26, 2018
    Here in the U.K. we are in the midst of a heat wave and my air con is blowing cold and then hot. It was charged today and revealed no leaks but as you drive it heats up.
     
  2. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,645
    Canada
    #2 moysiuan, Jun 26, 2018
    Could be the sensor that causes the condensor fan to go on is not working, and the fan is not working so the unit will work for a short time before it can no longer throw off heat at the condenser without the fan assistance. So check if the condenser fan is going on, it's in the left front wheel well behind the gills in there. Let the car idle for a while and the fan should cycle on. There is a sensor that clips onto a line out of the condensor, and detects the heat in the tube, and clicks the fan on after a certain temp is present. The idea is at speed, the airflow is sufficient to cool the condenser, and the fan clicks off, saving wear on the fan and fuel. Will usually be off til you come to a stop and idle for a while, then triggers on. Hard to tell against the radiator fans that also cycle on and off for their own sensors.

    Also, an overcharge would give this symptom, the system will work fine at start up, but as the pressures are too high as the unit overheats, the compressor shuts down to protect itself and it blows warm.
     
  3. PBonneau

    PBonneau Karting
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    Sep 14, 2013
    65
    Albuquerque, NM
    #3 PBonneau, Jun 28, 2018
    My 1986 3.2 Cab had a similar fault. After starting the car when the engine was cold the a/c would blow cold until the engine got warm. Then the a/c got warm. It turned out that the fault was in the electromagnetic valve which controls the flow of hot water into the heater box. The valve was stuck open which allowed the heater to over power the a/c evaporator. I made a simple repair... I had my mechanic install a manually controlled shut off valve in the hot water hose leading to the heater core. In the summer I shut the valve and the a/c is cold. In the winter I open the valve and the heater blows hot air. Maybe this will help you.

    Philippe
     
  4. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    #4 spicedriver, Jul 3, 2018
  5. afterburner

    afterburner F1 Rookie
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    Jun 20, 2008
    3,215
    Hong Kong
    #5 afterburner, Jul 13, 2018
    When mine was blowing cold then after warming up turned into warm air, it was the integrated relay one the HVAC ecu that had a failing solder point. It simply lost contact when getting hot. Resoldering solved the issue. That relay is controlling the power going to the a/c clutch. My heater was off the circuit at the time so I was sure it wasn't heating, eventhough the air coming from the HVAC was surprisingly hot.

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    Failing soldering:

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    Fixed:

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