overheating.. fan not coming on. help.

Might be a bad fan. Happened to me. It just died. Test it by connecting the battery terminals to it with small connectors. If it spins its not the problem. Then either test or get a new coolant temp sensor. MIGHT be a good idea to change thermostat too if you haven't.

The stock 94-95 GT fan is a two speed unit. Low speed comes on at ~208*F. High speed comes on at ~228*F. To check if the appropriate fan is being triggered by the computer:

To check low speed fan operation, look for 12 volts at CCRM pin 14 with ECT temps greater than ~208*F

To check high speed fan triggering, look for continuity to ground at CCRM Pin 17.



Be sure the fan connector is plugged in tight and that if it has a retrofit breaker, that it's not opening.


Manual fan switches


Fan relay diagnostics




General cooling system info

I have the same problem. My fan is not coming on when it gets warm. I just plugged in my code scanner and when it scans for codes low and high speed fans come on. What could be wrong with it?

drewzx3 said:

I have the same problem. My fan is not coming on when it gets warm. I just plugged in my code scanner and when it scans for codes low and high speed fans come on. What could be wrong with it?

Click to expand...

Run through these links to see what applies to you and we can narrow it down from there.........

Uno


See the fan relay diagnostics in this one:
Dos


The car will shut down your AC if temps get too high (I dont recall the number off the top of my head - it's around 240*F IIRC).

I cant tell what pin is what but my fan didnt come on until about 235* and it didnt cool it down. What sohuld I do?

drewzx3 said:

I cant tell what pin is what but my fan didnt come on until about 235* and it didnt cool it down. What sohuld I do?

Click to expand...

There are small numbers on the CCRM connector. See this diagram for the colors that correspond to the numbers.

What do you mean the fan didn't cool the car down? Was the fan running hard? Which fan speed was on? Was the AC turned on?

The ECT is the engine coolant temp sensor. It's located on the passenger side of the motor, to the passenger side of the thermostat.

The following diagram can help you find various components (it's for an aero fox but many of the components are in the same location). Thanks to Stang22 and Almost Stock for the picture.

http://leemotorsports.com/almoststock/50enginepartsguide.jpg


To test the ECT, probe the signal wire leaving the ECT. It will be about 0.5 Volts at 200*F and 0.35 Volts at about 230*F.

If that checks out ok, run the tests in the links (where you look for 12 volts at CCRM Pin 14 above 208*F, and so on).

It will take a little bit of time to diagnose this - otherwise people end up throwing parts and money away hoping they guess right.

Good luck.