Where is the heater control valve located on a 2003 Saturn Vue

Its a v6 awd and I took it took autozone and they said it had a vacuume leak and there are a couple of hoses that are attached to nothing we bought the car used a couple of month ago

Unconnected hose

I think the thermostat is working ok it stays between the quarter and half mark when im driving (its been cold here) but when im sitting still it stays at the half. I been reading alot (almost every page I could find on the internet) about what it could be and I found one thing saying that there could be air in the system. One page suggest that parking on a hill parking and letting it cool down then start it and let it warm up and take the radiator cap off and letting air out, my car doesnt have a radiator car so I just left the resevour cap off and I seen a bunch of air bubble come out and I cold smell like a faint smell of the heater work and had luke warm air. What could this mean

The luke warm air went away after a few minutes

One get a little warm and the other doesnt really get that warm I can hold them the whole time the car is on they never really get hot to the point I couldnt hold them I would say warm at best and it doest really feel like anything is running through either of them thats why I thought there was air in there its like a very minimun stream of liquid

I flush the core a bunch already I flushed it thru the outlet hose and then the inlet hose several times it flushes clean and nothing come out beside clean clear water, would it clean it better if I got some hot water and dumped it down the hose with a funnel, some pages even suggested using bleach to clean it and oven cleaner as a last resort

I looked at it more and I have noticed that its useing coolant and there are no visable leaks, and if I look from the passenger floorboard up under the center console and twist the heat/cold **** I can see it move I think its working because when its on cold it sounds much louder and its blowing harder than when its on hot, and my friend said someone might have used some of that leak stop stuff on it and when I flushed it out I did notice something that resembled that stuff. If someone did use that stuff on the system would water still be able to flow thru the heater core what kind of effects can that stop leak have on the cooling system

Ok last night my fiance took the vue to autozone because I went to check the transmission fluid and the entire tube came off cause it didnt have a bolt on it at all do you know what size bolt goes to that, and she had them check it again and this time they got the code P0128 and P0442 thank you for all of your help, so it look like I have to change the thermostat, I looked it up and this looks like alot of work on a scale of 1 -10 how hard is this to do?

I bought some of that lubricant for the cooling system and when I bleed the air out of the system I have heat for a few minutes and then it goes away I checked other forums and by what they said it could be a leaking head gasket cause no matter how many times I bleed the air out it keeps coming back, and I was wondering is the leakseal stuff would be a good short term fix until I get some more money, and what kind of affects that stuff can have on my cooling system, if I do go that route I plan on getting a fitting to bypass the heater core cause i've read that stuff clogs up the heater core

Is this the oil pan and if so what size allen wrench do I use, I want to change the oil cause I found a whiteish look film around my oil cap, this car is driving me crazy