I’m a newbie,,, so sorry for the ignorance. Love the car, race prepped and a lot of fun. Brand new rebuild. So, my silly question is about the vent in front of the wind screen… how do use raise it? I can find nothin in under or around the dash.

 

It is vacuum operated. On the centre console below the ashtray you should see 3 push buttons, marked "Air" "Heat" and "Off". Pushing the air button raises the vent, then pressing heat opens the heater valve and allows you to heat the incoming fresh air, off turns everything off and closes the vent.

If you just press "Heat" that opens the heater valve, but doesn't allow any incoming fresh air. To have heated, fresh air, you need to press air before heat.

 

Check on the bulkhead dead centre under the bonnet. There should be a round saucer shaped vacuum switch with a rubber tube going into it. When the button on the dash is pushed this saucer shaped vacuum switch operates a lever that opens the scuttle. On the Mk2 this was opened by a lever but the S Type went up market. Problem is the saucer shaped Vacuum switch can stop working and is no longer made so a previous owner might have removed it.

 

the Vacuum Actuator for the Scuttle Vent is located on-center below the vent itself mounted to the firewall in the engine compartment.

Cass calls it a "switch" but it is an "Actuator" operated by vacuum.

Those actuators can be rebuilt by a firm in Australia for approximately $85.00 USD.

while you get it repaired, use the Fan to get air ventilation. There is a switch in the row of switches that says "FAN". The switch has 3 positions: OFF-LOW SPEED-HIGH SPEED.
This Fan switch works with the TEMPERATURE LEVER, cold or hot or in-between.

All that assumes the actuator is bad, because it could be something else, for example, the rubber hose that goes from the AIR button to the actuator could be ruptured or even disconnected from the 3 button switching vacuum port.






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As it is Race prepped other considerations you might wish to consider other than in car-ventilation.

https://www.jaguarforums.com/forum/m...129320/page14/

 

Vacuum control scuttle vent. 66

 

If the vacuum is not working you might be sucking excess air into your intake manifold, which you need to address.
P.

 

this is the Scuttle Vent Actuator