Hi all,
I'm troubleshooting my car is constantly blowing hot air. I took the dash apart and have located the internals of the temp control knob. I can see that the knob is connected to a cable which mechanically operates some flaps. That part looks ok. I probed the two electrical contacts on the knob by measuring the electrical resistance and found that it acts like a switch (10% of the range (cold) gives a closed circuit and the other 90% (warm-hot) is open circuit).
Issues:
I disconnected the two wire harness connected to the heater control valve by the footwell and the voltage always reads 0V no matter what position I turn the temp control valve. It's supposed to be 12V when knob is cold and 0V when knob warm-hot. Strange considering my knob is correctly acting like a switch. Why is the voltage always 0V at the heater valve?
Thoughts:
1) There may be some kind of short to ground somewhere which is forcing everything to 0V
2) 12V is broken somewhere
Help:
Does anyone have any experience with this? I measured the voltage at the contacts on the temp knob and it always reads 0V so even if it's acting like a switch, it's just switching between 0V and 0V. Should it be reading 12V or maybe 5V for a relay?
Thanks for any suggestions/links/photos/etc...
-jeff
I'm troubleshooting my car is constantly blowing hot air. I took the dash apart and have located the internals of the temp control knob. I can see that the knob is connected to a cable which mechanically operates some flaps. That part looks ok. I probed the two electrical contacts on the knob by measuring the electrical resistance and found that it acts like a switch (10% of the range (cold) gives a closed circuit and the other 90% (warm-hot) is open circuit).
Issues:
I disconnected the two wire harness connected to the heater control valve by the footwell and the voltage always reads 0V no matter what position I turn the temp control valve. It's supposed to be 12V when knob is cold and 0V when knob warm-hot. Strange considering my knob is correctly acting like a switch. Why is the voltage always 0V at the heater valve?
Thoughts:
1) There may be some kind of short to ground somewhere which is forcing everything to 0V
2) 12V is broken somewhere
Help:
Does anyone have any experience with this? I measured the voltage at the contacts on the temp knob and it always reads 0V so even if it's acting like a switch, it's just switching between 0V and 0V. Should it be reading 12V or maybe 5V for a relay?
Thanks for any suggestions/links/photos/etc...
-jeff
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