1986 T/A 305 TPI, 700R4, 3:27 9 BOLT, 27,000 MILES. ORIGINAL & STOCK. AIR DEFLECTOR INTACT. CAME FROM THE FACTORY WITH A SINGLE COOLING FAN. THE ORIGINAL RADIATOR WAS REPLACED WITH A 3 FLUE BRASS UNIT. NEW 195 THERMOSTATE, HOSES, AND BELTS. CAR RAN AT NORMAL OPERATING TEMP (200) IN TOWN AND ON THE HIGHWAY, BUT OVERHEATED SEVERELY AND QUICKLY WHEN DRIVING SLOWLY IN THE MOUNTAINS. SINCE WE LIVE IN THE MOUNTIANS THIS WAS A PROBLEM. SWAPPED THE SINGLE FAN SET-UP FOR A FACTORY DUAL FAN SET-UP THAT I FOUND ON E-BAY. USED THE ORIGINAL POWER FEED FROM THE ECM TO CONTROL A 30 AMP RELAY PROVIDING POWER FOR BOTH FANS VIA A 60 AMP RELAY DESIGNED TO BE A BATTERY ISOLATOR SWITCH FOR AN RV. INSTALLED AN ADDITIONAL 195 ON/ 185 OFF TEMP SENDER IN THE RIGHT HEAD, WHICH CONTROLS A SECOND 30 AMP RELAY, THAT PROVIDES POWER TO THE SAME 60 AMP RELAY WHICH DIRECTLY POWERS THE FANS. THE WHOLE THING IS ROUTED THROUGH A 30 AMP CIRCUIT BREAKER WHICH IS CONNECTED DIRECTLY TO THE BATTERY. THE POWER SUPPLY FOR THE ADDED SYSTEM IS FEED FROM THE IGNITION SIDE OF THE ORIGINAL FAN RELAY. THE TWO RELAYS PREVENT A POWER FEEDBACK TO THE ECM FROM THE ADDED CIRCUIT. SINCE THE INITIAL POWER FOR THE TWO 30 AMP RELAYS COMES THROUGH THE IGNITION, THE FANS DO NOT RUN WITH THE KEY OFF. THE CAR RUNS GREAT. IT'S STILL LEGAL. BOTH FANS ARE ON IF WHEN THE A/C PRESSURE SWITCH ACTIVATES THEM, OR IF THE ENGINE TEMP IS ABOVE 195. THE TEMP STAYS BETWEEN 195 AND 200 IN TOWN OR ON THE HIGHWAY. LUGGING IT AROUND IN THE MOUNTAINS WITH THE AC ON, IT SOMETIMES BRIEFLY PEAKS AT 210, AND NO SWITCHES TO DISFIGURE THE DASH! IF ANYONE IS INTERESTED, I WILL POST A WIRING DIAGRAM AND BETTER DISCRIPTION OF THE PARTS USED.

 

Please do post the diagrams and any additional description of what you did. Thank you

 

I will post some diagrams as soon as I figure out how to download them onto this site. As for the large relay, it is a Tekonsha dual battery switch. The relay is self grounding, and has three terminals on it. Either of the large terminals can be supply or load, and the small center terminal is for the 12 volt coil. It is rated at 150 amps continous duty, and is available through PPL Motorhome Supply for approx $16.00 plus shipping. Physically it is about the size of a Ford starter relay, however the starter relays are not designed for continuous duty. The dual battery relay is a continuous duty unit. I have used these relays for everything from fan relays to starter solonoids on tractors and standby generators, some in service for more then 15years, and found them to be very durable.

 

I like that idea. Here's what I did when I swapped from mechanical to dual electrics:

https://www.thirdgen.org/forums/cool...electrics.html

JamesC