What Does This Sensor Do?
08-21-2004, 10:07 AM
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What Does This Sensor Do?
I have an 87 944 NA and am in the process of replacing a number of things. One of them is a tube that is under the intake manifold that comes out of the block and connects to the heater valve. I believe it is the supply for the hot water that comes from the block to the heater core. This tube has a sensor screwed into the top of it that connects to two vacuum lines. One of the connections on the sensor has a red tab on it and the other does not.
The question is what does this do? Also, does it matter which vacuum line is connected to the connector with the red tab on it? My guess is that it regulates the vacuum to the heater valve and does not allow it to operate until the water is hot enough to start heating. That is only a guess. If this is correct, then one of the lines would go to the heater valve to not allow it to operate until the water is hot.
Thanks to who ever can let me know what this is.
The question is what does this do? Also, does it matter which vacuum line is connected to the connector with the red tab on it? My guess is that it regulates the vacuum to the heater valve and does not allow it to operate until the water is hot enough to start heating. That is only a guess. If this is correct, then one of the lines would go to the heater valve to not allow it to operate until the water is hot.
Thanks to who ever can let me know what this is.
08-21-2004, 10:18 AM
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Think of the heater valve as a switch or a door that lets hot coolant into the heater core. When it's closed it just lets the coolant circulate through the engine and radiator. When it's open the heater core is added to the loop. The vacuum line supplies vacuum to the round diaphragm which controls the opening and closing of the valve via the rotary temp **** on the dash.
08-21-2004, 10:31 AM
#3
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What you are looking at is a temperature operated vacuum switch for the evaporative emissions cannister purge system.
The "switch" is set to open when coolant temperature reaches 58 degrees Celsius. When the switch is open the cannister is purged every time the throttle plate starts to open.
Check the vacuum diagram on the passenger side wheel arch just above the widshield washer tank.
The "switch" is set to open when coolant temperature reaches 58 degrees Celsius. When the switch is open the cannister is purged every time the throttle plate starts to open.
Check the vacuum diagram on the passenger side wheel arch just above the widshield washer tank.
08-21-2004, 12:14 PM
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Charlotte,
Thanks for the answer and I found the diagram. In looking at it, I assume that the vacuum line that connects to the connector with the tab goes to the throttle body. My diagram is kind of difficult to read, so that is why I am checking.
Thanks for the answer and I found the diagram. In looking at it, I assume that the vacuum line that connects to the connector with the tab goes to the throttle body. My diagram is kind of difficult to read, so that is why I am checking.
