With regard to the very high temperature (it is really, really, hot, almost painful to the touch) of the heated air, can that be influenced by 1) whether or not the flow restrictor arrow is pointed in the correct direction or 2 whether or not the flow restrictor is functioning properly? When I looked at the restrictor it was my initial judgement that is was a restrictor. However, on closer inspection, I noticed, what appears to be the cylindrical
shaped sleeve that restricts the flow, but it is moveable and is spring loaded. I clearly see how the sleeve restricts flow, but why is it moveable and spring loaded. I don't see how the position of the sleeve would alter the flow. Also, can you direct me to a flow diagram. Since I replaced the rubber portions of the hoses, I am thinking maybe I connected something wrong or have the restrictor in the wrong place.

Sorry to keep digging into this, but I have far above average experience working on automobiles and I am really stumped by this. Should the heat be so hot that it is uncomfortable to the touch? I have never seen an automobile heating system anywhere close to as hot as this. Let me give a llittle more background. For quite a long while (years) I had been hearing a noise in the vicinity of the drive belt and I noticed it took a long time for the heater to produce warm air. A few days ago, as I accelerated rapidly to get on interstate, out of the corner of my eye I saw the temp gauge peg high. Immediately pulled over. Plenty of coolant, recently had garage install new thermostat. Serpentine belt in tact. Finally limped home, couldn't find anything wrong. Long story short, the impeller had detached from the shaft inside the pump housing. Also noticed noise was no longer present. Replace water pump. Decided to replace rubber portions of heater hose. Used 5/8" heater hose, I cut to length. Started engine, that is when I noticed very hot heater air. Began to wonder if I had put flow restrictor in incorrectly. Reversed direction of restrictor, no change. Insnpected flow restrictor. You can see a hollow sleeve that serves to reduce the diameter. However, the sleeve is spring loaded and will move slightly (approx 1/4") if you insert a slender object and press on the sleeve. I could understand if this was simply an immovable sleeve. I am concerned that there is something wrong with this piece that is causing the heat to be much hotter than it should. I can't understand the need for the spring loading and the movement in the sleeve. It acts like core is getting way too much water. I am wondering if something has broken and is missing from inside the restrictor. I suspect impeller was slipping for a long time and I may have not had normal system flow. I am in a rural town without a dealer so I can't easily just go look at a new one. Have you ever know of any failures associated with the flow restrictor or any problems which creat an abnoramlly high heater output temp.?

I have rear heat but, as far as I know, I do not have the automatic system. I have a fan selector speed knob and a dual (driver side and passenger side) slider bar that I believe modulates dampers to vary the heat to each side. I assume a full auto system would have a control that establishes a set point about which either the fan speed or flow through the core would be modulated. Glad you mentinoed the point about the restrictor being brittle. While I was replacing the hose it cracked and I will have to order another one. I appreciate your patience. I think we have this about wrapped up. One last question, do you have any idea as to why there is a flow arrow on the restrictor or why it has the spring loaded moveable sleeve inside? I am familiar with industrial flow orifices and nearly all of them are simply fixed diameter flow restrictors.

Thanks George, when I get the replacement restrictor I think I will cut the old one on a band saw so I can see the cross section and figure out why it is built like it is. I appreciate your help.