This is the unit before I cracked it open. This is looking down on the top of the unit. The hole down through the white plastic is where the air would come out to go to your demisters.
If you were sitting in your car looking straight at the centre air vents in the dash.....this is what is directly behind them.
Now if you had the bonnet open (that's the hood for you Kevin) there is a back wall in the engine bay known as the firewall. I guess in the old days it was just that a wall that stopped the fire from a fuel fire, getting to the occupants in the car. Anyway if you could see through the firewall this would be the view you'd have of the heater. The two pipes at the top right of the picture carry hot water from the engine block cooling system into the heater core. You can just see the top of it. Its the copper coloured piece.
In fact here is the heater core, its basically just a small radiator, and in essence that is rows of small tubes joined by thin vanes. The heat from the water is transferred outwards through the copper tubes and into the vanes which are then cooled by air flowing through. That's how your cars radiator works to keep the engine cool. The heater core is no different except it is used more for the fact that it heats the air that's passing through it. That said though I have in the past turned the heater on flat out and the heater fan to full speed to try and help cool the cars engine down on a hot day. Kills the occupants in the car but it is surprising how effective this can be at helping to bring the engine temperature down. Oh sorry.... almost forgot to show you the heater core.
Okay so what is inside this third unit? Like I said pretty simple at first glance. This is looking down inside the bottom half. Basically just a few air flow control flaps.
The only other thing to note here is the small silver rectangle to the left. Here's a closer look.
It is one of the many sensors that the brain of the Climate (automatic) aircon uses to assess whats going on. The heater core sits right down on top of that silver metal box, which is basically an electronic thermometer telling the aircon how much heat is available from the heater core.
This next pic is looking up inside the top half of the unit. The heater core is still inside it. Sorry its a bit blurry. To the right you can see more airflow control flaps.
It took hours to restore this unit as all the control flaps had to be relined with sponge/foam as all the old stuff was rotten. Not much was left and what was, was all crumbly and basically would have served no purpose. There are no fewer than about 7 or 8 flaps in total and most had to be covered on both sides.
Anyway with all that done let me show you how it works....
Remember air comes in from either inside the car (recirculating) or from outside (fresh) and is forced in by the heater blower motor. That was the first unit.
If the aircon is on the air is chilled in the second unit. If not it is kept at the ambient temperature.
Now the air arrives at the heater box. This next pic shows the heater in the closed position. The flaps are covering the heater core so the air doesn't go through it and get warmed up. We'll look at it a bit later but the motor that operates these flaps also operates a tap controlling the flow of hot water into the heater core....so when the flaps are closed like this....so is the hot water turned off.
Now as the flaps are opened to let air through the heater core to warm up, so does the water tap open and let the hot water flow. Quite clever that one motor serves both purposes I thought.
Looking at the front of the unit you can see here a few more of the control flaps. The one on top at the right is the hole that air for the demisters comes through.
The hole in the top to the left and the one on the front on the left both act like a bypass. It seems that no matter what position the flaps are in there is always some air flowing to the centre face vents.
The front right flap controls the bulk of the air going to the face vents. Then at the bottom, you can't quite see the flap but the hole there is where the air comes from to go to the foot vents.
All of that you have seen above gets covered up by plastic mouldings that direct the air to various pipes to take it out to the vents you use in the car. I'm going to have to make something to adapt this as the unit won't be marrying up to a Toyota Celica dashboard like it once did.
Anyway here it is with that moulding in place. Now when I say I will need to make something to adapt....its not quite true as I have a lovely assistant helping me out. I have employed the services of Tony Field to weld some adapter plates up. I have made patterns for what are basically metal plates that will screw over all the outlets and have a piece of pipe welded on to them that I can later attach the ducting to.
Okay, remember I said I'd show you the motor that controls the flaps and heater tap...... here it is. The black box is the motor which the Climate air brain (computer) controls, by telling it to open or close or stop at any position in between. The black cable is what operates the heater tap, while the white plastic arms (and the rods coming off them) are operating the air flow flaps.
Here's a picture of those control arms without the motor covering them.
Pretty smart cookie that designed that eh!!!!
I tell you what, he wasn't that clever at all..... just the apprentice I think..... the real bright bugger was the one who figured out a way to have one other servo motor control the airflow to face only, feet only, demist only, face and feet, feet and demist oh and of course demist and face. So not only does the one motor control all these combination's it also opens, closes and partially opens the various flaps all in the right sequence. There are about 6 flaps to operate here remember. How the hell they worked that out I'll never know. I reckon I'd have more chance of solving the rubics cube with a blindfold on and that ain't gonna happen.
Anyway this is what operates it all. A large wheel that has worm shaped cutout that push up and down on various levers that push and pull on the airflow flaps. There are more controls behind the motor as well. Very clever.
Actually while we are looking at this pic you can see a white plastic thing that looks a bit like a microphone.....just another sensor for the computer.....this one measures the ambient air temperature in the car.
the big black hole to the left is where the air comes from for your side air vents at either end of the dashboard.
Then finally the computer (brain) screws on over the top. That's the cream coloured box.
I couldn't resist opening it up to have a nosey. Not quite true I opened up the other one I had sitting here as I was frightened I might damage something.
No comment required I'm sure. The pictures speak for themselves.
Last but not least here are some before and after shots of the whole unit all back together again. Man I hope I can get it to fit!!!!
BEFORE
AFTER
BEFORE
AFTER
BEFORE
AFTER
And that about wraps it up before I wrap it all up in plastic and store it. I'll do one more post on it once I have the adapter plates back from Tony.
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I really appriciate your work. thanks for giving us information .keep it up.
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