Question about 1986 Porsche 944

1 Answer

Cant turn the heating down

Even with the heater control set on cold in my 1988 944(without a/c) the heat coming out the vents is unbearable.How does the heater control work and how can i fix it by summer?

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  • tjgecj Mar 01, 2009

    found the valve and it,s working ok ,but it only activates in the off position for about 2 mins from start up then opens and the interior gets hot.

  • tjgecj Mar 03, 2009

    I have taken the valve off the car ,tested it ,it's not letting bye. I think it must be the control unit situated to the left of the steering column.does anybody know how this works or how to test it? thanks Ian

  • dreamderekng May 07, 2009

    the heat will not stop blowing on my 1986 944 porsche

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  • Master
  • 3,533 Answers

Need to find out where the heater control valve is located (it normally is near the engine inside the hoses) and see if that is sticking and if you cannot free it up replace it

Posted on Feb 28, 2009

  • 1 more comment 
  • edgar walker
    edgar walker Mar 01, 2009

    if it was me i would replace it and tyhen you be all set

  • edgar walker
    edgar walker Mar 01, 2009

    if it was me i would replace the valve and then you be all set

  • edgar walker
    edgar walker Mar 04, 2009

    you can try your local library for more information on heater control valve and they even make copies of the diagrams for you

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NO HEAT ON FLOOR VENTS

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As per your problem mentioned. There are few solved help links to troubleshoot these problems. Go through the list and Click the link below:----

2000 Toyota Avalon: No heat on Passenger Side?

http://whatisbyme.blogspot.in/2012/05/2000-toyota-avalon-no-heat-on-passenger.html


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No heat on Oldsmobile Silhouette?


http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.html

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http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

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http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

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http://repairhelpcenter.blogspot.com/2012/01/hot-air-on-drivers-side-vents-only.html

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http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html

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These will help.

Thanks.

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1 Answer

Rear vents blow out hot air when a/c is on


Keep this principle in mind: Heat, flows INTO cold... When you hold an ice cube in your hand, your hand gets cold because the heat from your hand is flowing INTO the clod ice cube, NOT because the cold is flowing into your hand.

On this particular vehicle (like many modern vehicles), hot water from the engine flows through the heater core at all times, even when you have the A/C on or when you have nothing (A/C, heat or vent) on. The system uses a door that closes down over the air opening to the heater core to keep you from feeling warm/hot air when it is not desired. The reason(s) you feel that the vent air is warm even when the outside temperature is somewhat cool is/could be caused by the following:

First, although as mentioned above, the heater core is restricted from receiving air when you are not commanding heat by the control panel, the heater core ultimately ends up as warm as the engine temperature. This is generally somewhere around 200 degrees F. Because all the air coming out of your vent(s) must pass over the door that restricts air over the heater core, and because the heater core gets so hot, some of that heat is picked up by air passing over the hot door even though it is closed.

Second, the door that restricts airflow from passing over the heater core has a seal around it. After a period of time this rubber (or usually felt) seal deteriorates, allowing some air to actually pass over the heater core. Since the core is hot all the time, some of the air gets heat loaded, producing warmed air.

Third, the door is operated by (in the case of your vehicle) an electric motor which responds gradually/proportionately to the setting you select on the temperature dial. If the motor gets out of calibration (can happen from time to time), if the control head has a 'glitch' and sends an incorrect signal (chronically, usually), or if the electric motor (called an actuator and contains its own little electronic 'brain') becomes faulty, the door may not be closing completely. This symptom can also be caused by a problem with the door itself, where the door gets stuck due to warping of the plastic case, a foreign object preventing it from closing (usually a pen or toy dropped into a vent or defrost opening), or a broken or cracked door hinge.

Last, the vent intake opening, where the 'fresh' air comes into the car on the 'vent' setting, is located just below the windshield on the passenger side. This opening receives its air directly off of the sun-baked, engine-heated hood and because of this the air is never as cool as outside air even on a cooler night.

I hope this answers your question. Many domestic vehicle manufacturers have begun installing heater control valves on their vehicles once again as they nearly all used to have. Note that the fix for most everything I have mentioned here requires removal of the dash of the vehicle or replacement of the control head and therefore is in many cases not worth the investment if it is not an extreme problem (for example, unless the system is stuck on full heat in the middle of summer. Additionally, remember that, if you so desire, manual shutoff valves can be placed in the heater hose lines (please consult a qualified mechanic as water from a vehicle can and will scald and burn you!), allowing you to manually shut off the flow of water into the heater core, thus reducing some of the heat (Readers note that certain foreign vehicles REQUIRE water flow through the heater core at all times for engine cooling and are not candidates for this procedure!).


Parts Of BMW.

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