Ford Repair: 99 Mustang Fan, mustang fan, jumper wire

Question
The electric fan on my 99 Mustang intermittently stops in city driving. I base this on the air conditioner not blowing cool. Also I've see the temperature gage start to rise at stop lights. I think that it is the fan relay or the temperature sensor but I don't know where these are located. Can you tell me where the fan relay and temperature sensor is located?  

Answer
Tom,

The fan relay should be incorperated in a module above the radiator support called the IRCM.  I would check to see if the fan has a bad spot in the winding first. If it lands on the spot it won't run. Unplug the fan connector and run a jumper wire from the fan motor to the battery positive. Now connect a test light from ground to the other fan terminal. The light should come on, but the fan will not run. Now spin the fan by hand and watch the test light. If it goes out at any point you have a bad spot in the fan motor. The IRCM uses a signal from the engine ECM to turn on the fan. Also, if it is a two speed fan you may only have the low speed broken causing the A/C to warm up.