[DML] Thermal Time Switch

["bitsyncmater" <david.mckeen@xxxxxxxxxxxx>]

Ran testing on my thermal time switch.  Markings on the each side of 
the brass hex switch are:

VDO made in Germany
3.80
35/5/19 max 150 C
35 C
-20 C 7.5 sec.
12 V 40 W

One thing I discovered is when the switch is open it really is 120 
ohms.  I guessing they put a 120 resistor inside the switch to keep 
some current (100 ma) flowing through the CSV to reduce burning the 
contacts (switching inductive loads makes sparks when contacts open).

My switch will open a 98.2 F and close at 95.8 F.  note: closed is 
0.6 ohms.
Also to note the internal heater resistance is 29.8 ohms.

The test was run with a FLUKE 52 thermometer calibrated on 09/10/2007
The switch was submerged in hot water to the top of the threads.
I let the hot water cool until the switch opened.
After letting the switch cool to 90 F, I added heat with a soldering 
iron stirring the water so it would heat slowly until I could read 
the open temperature.

It takes a long time for the hot water (160 F) to cool to 95.8 F at 
my room temp of 75 F.  About three hours.  When my car is sitting out 
in the hot parking lot with summer temps in the mid 90s.....It would 
take much longer than 4 hours to cool so the CSV would activate.

Don't know why so many are convinced that the cold start valve is 
used to start a warm engine.




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