Coolant Temp Sensor and HEAT

Dec 21, 2005 4 Replies
T

Hi All!



I have an 1984 Cadillac Fleetwood. A read the trouble codes. The is code 15. Open coolant sensor circuit.



In the diagnostic test there is -40 celsius from the CTS. And i haven't got any HEAT. The blower works, but the air is cold.



Maybe i haven't got heating because the CTS is bad? Where is the coolant temp sensor in the car?



Other: The cold air goes from the defrost intake. Both hoses are hot at the heater core. Heater valve is OK. How can I see the AIR MIX DOOR or MODE DOOR problem??? How can I diagnose this problem? In heater mode why cold air comes like defrost mode?



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P

Check all the electrical connections from the sensor back. Check wiring for; bad terminal connections/bad wire/faulty mating of the cts terminals/connectors. Once you are sure of the wiring, then there is a long diagnostic list to try. It starts with disconnecting the cts and putting a jumper wire between the terminals in the wire harness. If the parameter value then is: -40 to -35, there is one ladder to follow. If the value is -34 to 151 there is different ladder to follow.

One of the electrical inputs the air-mix valve is adjusted by is, the cts value.

When/if the cts value is wrong, as seen by the computer, it then uses the mat sensor value to operate.

I'm willing to help, so read the values with the jumper-wire in place and post them. Is your email addy right? I may go to my pc instead of this terminal.

Dave S(Texas)

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