Coolant Temp Sensor and HEAT

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?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
CTS is near the thermost housing on the intake manifold, 2 wire connector. If both hoses are hot the problem is usually in the temp door controls, this system is automatically controlled by thermistaors and a dial rheostat, sending a signal to a programmer which in turn moves the temp door based on in car temps, outside temp and dial setting, it is underneath/ behind the glove box.

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Keep in mind the climate control sytsem on the Cad. uses the cts to decide whether to allow the blower to actuate, so it still may be seperate problem for that issue.

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.