Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Component Test









Compare the resiance reading between the No. 1 and No. 2 terminals of the heater core temperature sensor with specifications shown in the graph: It should be within specifications.

Resistance at 68° F (20° C): approx. 7 K Ohms

NOTE: Dip the sensor in ice water and measure the resistance. Then pour hot water on the sensor and check for change in resistance.

CAUTION: The sensor uses a thermistor which can be damaged if high current is applied to it during testing. Therefore, use a circuit tester that puts out a measuring current of 1 mA or less. (At 20 K Ohm range)