Ok - this is new, huge cloud of steam of some king bellowing from under my hood
06-14-2007, 11:36 PM
#16
Chronic Tool Dropper
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Lifetime Rennlist
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The pre-GTS cars may or may not have high=pressure cutoff in the pressure switch. The wiring diagram for my S4 has the symbol for a dual switch, but per Alan the dual switch has more electrical connections than the two on mine. Hmmm.
The schraeder valve port there on the tubing manifold is where the pressure switch (and the pressure transducer on S4+ cars with variable fans) screws on. The 'cap' there is supposed to be the switch.
In the top middle of the drier on mine is what looks like a blow-out plug. If you have an extra "vent" there now, you probably need a new drier. (see my post #2 above...). You'll need one anyway now that air is in the system no matter what.
For thoose reading along at home, this is the one failure mode that keeps me from recommending R-134a for pre-S4 cars. All it takes is a cooling fan failure on a hot day, and you have a problem like this. The R-134a has a pretty steep "knee" in the temp-vs-pressure curve that spikes pressure higher than R-12 under this extreme condition. You --will-- find the weak spot. This is also a reason not to use any of the iso-butane blended R-12 replacements. Sudden mass release of that, with oil entrained, is a fire looking to happen if the hood is closed and the gas contacts a hot exhaust manifold.
The schraeder valve port there on the tubing manifold is where the pressure switch (and the pressure transducer on S4+ cars with variable fans) screws on. The 'cap' there is supposed to be the switch.
In the top middle of the drier on mine is what looks like a blow-out plug. If you have an extra "vent" there now, you probably need a new drier. (see my post #2 above...). You'll need one anyway now that air is in the system no matter what.
For thoose reading along at home, this is the one failure mode that keeps me from recommending R-134a for pre-S4 cars. All it takes is a cooling fan failure on a hot day, and you have a problem like this. The R-134a has a pretty steep "knee" in the temp-vs-pressure curve that spikes pressure higher than R-12 under this extreme condition. You --will-- find the weak spot. This is also a reason not to use any of the iso-butane blended R-12 replacements. Sudden mass release of that, with oil entrained, is a fire looking to happen if the hood is closed and the gas contacts a hot exhaust manifold.
