[DeTomaso] Late Model Pantera A/C experts?

Julian Kift julian_kift at hotmail.com
Thu Aug 20 17:42:41 EDT 2009


Charlie,

 

Generally when the A/C is switched on, vacuum is channeled through the switch and vacuum lines to the servo motor responsible for opening the duct door, which directs the correct amount of cool or ambient air into the vehicle's cabin. 

 

I'm not sure how the later Pantera A/C (isn't it a Maserati system?) functions in terms of the active temp control, but from your description it sounds like an air temperature sensor cycles the compressor on and off at the desired set cabin temp. Normally the vacuum servo side of type if A/C i.e. ducts/flaps would be independent of the electrical side. So here is pure speculation and postulation on my part....

 

The repetitive whoosh is a problem with the outside air duct flap not closing (vacuum closed, normally open) either due to a bad hinge or more likely organic debris blocking it. In the Pantera the air temperature sensor is close enough to that duct that it does not reach low enough T to switch off the compressor.

 

As always this is better understood with visual aids and the following provides a good schematic and operation of a Maserati A/C system, including the vacuum side and flap positions etc.

 

http://www.maserati-alfieri.co.uk/alfieri155-4.htm

 

Additionally Wilkinson's catalog page for a late style A/C system shows the air temp sensor as #6 and attached to the A/C control panel with #5 being the vacuum valve

 

http://www.panterasbywilkinson.com/webpages/catalog/ill20.html

 

Good luck,

Julian

 

 
> > Late model Panteras have a vacuum operated system - a series of 
> > doors that
> > open and close to direct air to where you'd like it that use vacuum 
> > instead
> > of mechanical connections. The A/C compressor cycles on and off to 
> > maitain
> > the desired temperature, and each time the compressor cycles on or 
> > off, the
> > "fan" light in the speedo lights or turns off and there is an 
> > accompanying
> > "whoosh" of air, sort of like a truck's airbrakes, but mini-scale.
> >
> >
> >
> > Anyway, starting yesterday, I could hear the whoosh when the cabin 
> > reached
> > the desired temperature, but it would appear that whatever the air 
> > is trying
> > to move must be stuck. the whoosh repeats, and repeats, and repeats, 
> > trying
> > to move whatever it needs to move but without success. the 
> > compressor stays
> > connected and will never cycle off. If I manually roll the temperature
> > selector to basically "off", there is a whoosh and the compressor 
> > shuts off.
> >
> > I deduce that the thermostat is working and trying to send a signal to
> > whatever air device shuts off the cooling function but it sticks. 
> > But I can
> > shut it off manually if I turn the temperature wheel to minimum.
> >
> > a) Anyone know how the thermostat functions in the late model
> > Panteras? What happens when the desired interior temperature is 
> > reached?
> >
> > b) Will it hurt anything if the compressor runs non-stop 
> > continuously?
> > For hours at a time? Is there something that could freeze, or 
> > overheat, or
> > something bad?
> >
> > Horrible description of the problem but hopefully people who have 
> > seen the
> > system will understand what I'm trying to describe?
> >
> > Charles McCall
> >
> > 1985 DeTomaso Pantera GT5-S #9375
> >
> > "Raising Pantera Awareness Across Europe"
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