Heater deforster problem

The bi level control is vacuum operated and often on the older commodores and utes the vacuum switch and or hoses are at fault, listen under the dash drivers side next to console for any hissing noises.

There should be vacuum, check the hose (small) going through the fire wall and hooking into the inlet manifold at the rear, that is the vacuum supply line.

Just been re thinking, have a look around the throttle body underneath and at the rear, been a while sine I did a VP, check the length of the hose and see wher it lays around the manifold, I will still try to find the exact port in a manual and re post.

Just had a thought, I think the VP had a vacuum accumulator under the front of the L/H/ guard, so lay the loose vacuum hose along the fire wall and you may find the rest of the hose going to the accumulator, I will check further.

Your in luck, I just had a 5 litre VP booked in for later to day, when it gets here I will have a look at the system.

It just got towed in. On the L/H side of the fire wall there is a round rubber grommet with one vacuum hose and below that a small pipe (part of the A/C system) the vac hose run along the L/H guard behind the strut tower and it goes to the vac accumulator under the guard, a second vac hose is seen here as well that is the vac line that runs to behind the inlet manifold, problem will be that as this also has gas, all the coolant hoses make it very difficult to see wher it actually goes, I think that this car has a stuffed distributor so if I have to take it out later to day I may see some more. Stay tuned.