Volkswagen Repair: air lock in cabin heater, wv polo, rubber cone

Question
I have a WV polo 1.4GL

I have just replaced a faulty thermostate, but not the cabin heater is not working. I beleave nearly 100% that it is because of air in this part of the system.

Can you tell me how to remove this air?

I have tried filling the tank slowly as instructed in the haynes manule, and squeezing the pipes, but it has not helped.

Thanks Richard.

Answer
Hi Richard;
Many of the questions I have answered are to do with this very problem.  There is a special tool that is used to evacuate the cooling system in all Volkswagens.  It is called "Air-Lift."  It is a gauge, a rubber cone(upside down), and a pair of tubes with fittings.  You must have shop air, or a compressor to pull a 1.2 atmosphere vacuum into the cooling system.  At that point it's just a matter of changing fittings, and filling with fresh low phosphate Volkswagen coolant.  Once you have the tool, and access to an air compressor, get fresh coolant. Don't try to reuse the stuff that's been heated and cooled at an air lock boundary inside the cooling system.  It has probably already formed a crust inside the heater core, or next to it. Get that stuff out, and some clean fresh stuff in, and disolve that crust so your heater can work freely again.
Good luck, Richard.  Hope this helps.