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George H.
George H., ASE Master Technician
Category: Chrysler
Satisfied Customers: 18765
Experience:  ASE Master Tech 15+ Years
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Chrysler town and country I have a 2002 Town and Country,

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I have a 2002 Town and Country, 3.8L. There is a component with a flow arrow in one of the heater hoses near the front heater core. Can you tell me the function of the component? Also, can you tell me where I may be able to see a heater hose diagram on the internet?

Hello I will help you with your question,


This is a flow restricter and keeps the heater core quiet and slows the coolant flow to reduce the erosion from the coolant through the core.


Let me know what further questions you have about this



Thank you



Customer: replied 6 years ago.
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.

There are no flow diagrams produced for the service industry and I have to work from experience here. I know if the restricter is not installed the core will fail in a few weeks time from the increased flow.


The heat sounds good but how is the cooling? If there is no flow through the AC evaporator you will not have defrost/defog function so that needs to be checked.


Is this a full automatic system? If so has the calibration and operation test been run?


Let me know what I can do to help





Customer: replied 6 years ago.
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.?

The only failures of the restricter that I am aware of is that it will become brittle and shatter. The restricter is before the heater core to slow the coolant coming in so I wonder if you have it in the wrong hose? The OEM hoses are molded to only fit one way. The coolant will be about 200 degrees so if you have 150 air out of the center vent with the fan on medium that is normal. This will burn you if you keep it on this setting for long but you have a lot of area to heat so you can turn the blower up to get the cabin warm quickly then moderate the temperature from the vents by adjusting the blend door.


The automatic system has an infra red temp sensor to set the output temp so I come back to my original question, has the system been calibrated? Is this a full auto system?


You may find this diagram useful (Click here) If you have an engine oil cooler the diagram will be different as it will be if you have a rear heat unit.



By the way the problem with the impeller is well documented


Let me know





Customer: replied 6 years ago.
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.

The arrow should point to the heater core when the restricter is placed in the engine to heater inlet line. I don't know the engineering behind the design but it does work and if you leave it out you will be replacing the heater core in a few weeks.


If you have the manual system with rear heat use the diagram below


Click here


Note that the engine outlet runs to the lower heater inlet pipe.



Try this procedure to calibrate your system.


Click here


Let me know what I can do to help you with this



Thank you





George H. and other Chrysler Specialists are ready to help you
Customer: replied 6 years ago.
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.

OK please let me know if there is anything I can do to help


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