Hello,
I try to understand how the fan is working on my 92 RS TBI.
My previous car was an 86 IROC with a single fan. But, long time ago, I had read that on my IROC there was no fan switch. On a TPI, the CTS inform the ECM when to energize the fan. Right?

Now on my 92 RS TBI, there's always one single fan but there"s one sensor more : the fan switch.
Now I try to understand. The CTS displays the engine temp on the board end the CTS informs the ECM about the engine temp to modifiy the advance, right?
What is the rule of the fan switch?
1 - Is it a thermostatic sensor which energizes directly the fan?
2 - Is it a thermostatic sensor which informs the ECM about the engine temp and the ECM energizes the fan?

 

On my '88, the Coolant Temp Switch and A/C Pressure Switch will turn the fan on directly without involving the ECM. A/C Control Head is also shown in the wiring diagram. I'm not 100% sure what this is, but I assume it means the actual HVAC controls in the console.

The only thing Autozone is good for:
http://www.autozone.com/servlet/UiBr...3d80199c9f.jsp

Wiring diagrams can be found in the Chassis Electrical section.