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Heater Temperature - Only full hot.


pmdw1
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My LP640 heater blows fine (fan speed changes as it should) but doesn't have any heat until the temp is set to max, when it suddenly becomes red hot. There's nothing in between. Any idea's what the likely cause is?

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your Heater Control Valve/Water Solenoid (410260155) that provides the level of hot fluid to the core in the main hvac unit is probably blocked "and or" corroded and is only responding to a full open.

 

 

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your Heater Control Valve/Water Solenoid (410260155) that provides the level of hot fluid to the core in the main hvac unit is probably blocked "and or" corroded and is only responding to a full open.

 

 

Great response. Could it also need to be bled? I know I had a problem with a heater core one time, and there was air in the line causing it to not work properly.

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Great response. Could it also need to be bled? I know I had a problem with a heater core one time, and there was air in the line causing it to not work properly.

 

 

How would you bleed that? When I changed some hoses and coolant on my Murci, it seemed the system is well designed to burp itself, unlike some modern cars.

 

I guess you could drain the system and use a vacuum filler like I do for my daily drivers. My old cars either bleed themselves or have specific bleed points.

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If it goes hot only in max position sound more like in car temp sensor issue.

 

 

The controller has fault codes that will display in the event of a temp sensor failure, there would be a very good chance of a flashing code during operation if this happened.

 

E0 thru E9 then/or Ea thru EE

 

it is interesting that the Servo Valve even though it has position information to the computer, it does not have a fault code that displays as a warning on the screen in the event it fails due to a jamb or such.

 

also, if the resistor wipe has worn internally on the servo valve, it may only give a feedback of a certain value, and that may arbitrarily be wide open.

 

there is also a re-circulation pump for the feed to the heat exchanger, but i seriously doubt that would be the issue, if it failed you would just get uneven bouts of warm to hot then warm, based on engine RMP

 

I would put my money on the servo valve.

 

and, if you need to get a cost effective one that is identical to the Lamborghini, I will mildly point you in the direction of Maserati, they have two such valves (left and right), one is the direct "plug in"replacement...

 

Right Heater Water Control TGK Valve 67635900 Maserati Quattroporte M139

 

in case anyone is interested.

Thank you for reading.....

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and, if you need to get a cost effective one that is identical to the Lamborghini, I will mildly point you in the direction of Maserati, they have two such valves (left and right), one is the direct "plug in"replacement...

 

Right Heater Water Control TGK Valve 67635900 Maserati Quattroporte M139

 

in case anyone is interested.

Thank you for reading.....

 

We love any and all cross references! Thank you!

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