How does the cooling system of a F136 work?

[Jaz]

Hi there,

Can anyone please help me to understand how the small cooling circuit works? The big one (engine) is fairly simple, the small (HVAC) one is not.

If I got that correctly, it all starts with a branch from the big circuit (item 22 upper, all pictures below). The branch is then split into two parts (upper and lower) and both connect to a dual-valve (called TGK?). Next both lines connect to the firewall and disappear.

But there also is a line returning from the firewall (item 14 lower). It is connected to an electrical water pump (9 lower). Its output is forwarded (by 19 lower) to a T-junction (item 23 upper). Both ends are connected to something (to each cylinder head, maybe..?).


Where am I right and where am I wrong? In which direction does the water flow? What do the TGK valves do? And what happens behind the firewall (in the HVAC, I guess)? What is the return line (item 14 lower), which is connected to the electrical water pump? And what does this pump supply, is it really the cylinder heads?

Thanks for any help!
Jaz




Picture 023 - Cooling System: Nourice And Lines:

Picture 080 - AC Unit Engine Compartment Devices:

 

[Zep]

There are three parts to a HVAC system.

H for heating uses the hot water from the engine cooling system to heater the cabin air if required.

V for ventilation - a fan in the cabin moved air around, over the heating coil and:

AC for Air conditioning. This this a sealed
Circuit which used refrigerant and a vapour compression cycle to remove heat from the cabin. It used the same principles as building a/c or your fridge. The compressor compressed the gas which then goes to the condenser, is condensed into liquid by losing heat to the outside air, then goes through the engine bay to the bulkhead where the TGK valve reduces the pressure using a variable orifice. This caused the refrigerant to boil in the evaporator picking up heat from the cabin and that gas then goes back to the compressor.

None of this is specific to the F136 engine, pretty much all ICE cars work like this.

 

[Jaz]

Thanks for your reply, Zep!

Using your post, I'm looking for the H in HVAC. That is the water circuit. I believe there are TGK valves, too. At least this is how the part catalogue calls them. However, they probably have a different meaning there, as there should be no need to modulate pressure at this part. Maybe they modulate flow. But I don't know what the TGKs are responsible for here at all.

Do they take care of the heating level? E.g. "hot" commands them open and "cold" closes them? But why are there two of them? One for the drivers side and the other for the passengers side? Or front vs. back?

Or do they work in tandem? E.g. while the first opens, the other closes? To maintain a constant water flow for cooling the cylinder heads? (In case they are connected to the cylinder heads at all.)

 

[corradokid]

More commonly labelled as heater taps. Restrict flow as you say depending on internal temp requested. Sided for passenger/driver as different temps can be requested. Can be one heater matrix (radiator) internally with temps controlled by flaps within the hvac box or two separate for each side. What’s your actual concern or just interested?

 

[Jaz]

I like to install an electric heater. It will heat up the coolant which in turn will heat up the engine and avoids cold starts. I need to know some specifics of the small water circuit in order to install the heater properly. Thanks for your help so far!

Do you (or anyone else) know the flow direction? Looking at the water pump design my guess is: cylinder head -> pump -> HVAC -> TGK -> main circuit/reservoir. Can you confirm?