Roadfly.com         Roadfly Home | Features | Car Review Videos | Car Reviews | Cars For Sale | Used Car Parts Classifieds | Forum | Car Review Archives | Forum Archives Index



PDA



mark
08-21-2001, 05:46 PM
Subject: 86 L7, air conditioning system<br>In a correctly operating car, can you run the a/c and NOT have the system in the recirculate mode? If I select either a/c button on mine the light above the recirc button also comes on, and the outside vents close. If I select the recirc button the a/c always comes on. Was the recirc button added just to have another button in the system?? Maybe someone would care to explain. Just curious.<br>Mark

Bruce H ATL 85 745
08-21-2001, 07:14 PM
<i><br>Subject: 86 L7, air conditioning system<br>In a correctly operating car, can you run the a/c and NOT have the system in the recirculate mode? If I select either a/c button on mine the light above the recirc button also comes on, and the outside vents close. If I select the recirc button the a/c always comes on. Was the recirc button added just to have another button in the system?? Maybe someone would care to explain. Just curious.<br>Mark<p></i><br>Mark,<br>The recirc LED should come on only when the recirc button is pushed and not at any other time.<br>Bruce

Steve Hillman
08-23-2001, 02:54 PM
<i><p>Subject: 86 L7, air conditioning system<br>In a correctly operating car, can you run the a/c and NOT have the system in the recirculate mode? If I select either a/c button on mine the light above the recirc button also comes on, and the outside vents close. If I select the recirc button the a/c always comes on. Was the recirc button added just to have another button in the system?? Maybe someone would care to explain. Just curious.<br>Mark<p><br>Mark,<br>The recirc LED should come on only when the recirc button is pushed and not at any other time.<br>Bruce<p><p>Actually that's not entirely true. In A/C mode, the system will automatically go into "recirc" mode if the temperature differential dictates (i.e. when you first start the system up and the car is baking hot).<p>I have a diagram that matches flap position to HVAC cycle and according to that diagram, the recirc flaps are open for the first "8%" of the control unit lever movement. From what I have been able to determine so far, the control unit is an integral part of the HVAC system that monitors air flow, air temperature from two sensors (cabin and exterior), and the setting of the temperature knob on the dashboard and generates output control signals accordingly. It's not the same as the circuit board that houses the 6 buttons and two rotating knobs - it's some sort of electro-mechanical device attached to the main HVAC unit. <p>I'll have to get familiar with it soon as I'm pretty sure mine is acting up - I get strange things happening to the system depending on how much airflow there is (the system will switch back to defrost under heavy acceleration, but ONLY if the fan is blowing fairly hard - if the fan speed is at one of the "." settings, it doesn't happen!. I also never get any air out of the defrost vents the rest of the time unless I press the defrost button. The rest of the time, my windows steam up!)<p>Steve Hillman<br>'85 735i 5spd<p></i>

Russ
08-23-2001, 04:14 PM
The HVAC system is one designed to operate automatically, that is you set the desired temperature and the system does the rest. What that translates to is that if the cabin temperature is colder than the setpoint, the HVAC system will automatically open the outside louvers and close the cabin return vent so that the setpoint can be obtained using whe warmer outside air. When the cabin temp exceeds the setpoint, the outside louvers close and the cabin inlet reopens to recirculate the cooler internal air. If your variable speed blower dial doesn't work like mine doesn't, then you have a situation where this process may cycle constantly if the blower is set to run @ full speed. <br>The RECIR button forces the system to always use inside air which will cause a loss of cabin temperature control because the system has no way to regulate the inlet air temperature.


Roadfly Home | Car Reviews | Forum Archives Index