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94 Concorde 3.3L. CEL comes on as as weather is warm out, like 10 degrees celsius, the CEL will come on within the first 30 seconds of driving. Overtime the car overheats and the fans aren't on. I changed temp sensor and swaped relays to see if anu were broken. Sometimes I will start the car, with AC on and the fans will run, even when I turn off the AC. If I turn the car off and start it again with the AC on, then the fans won't turn on.

Why the hell won't my fans run properly. The CEL is code 35 for open relay circuit. I'm guessing it is wiring... But, why the hell would this not occur when the temperature is cold out? Doesn't make sense to me, the fans seem to always work in cold weather. Thats why I thought maybe it was the coolant temp. sensor, but that is obviously not the case.
 

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I'm thinking it's something to do the the RFI suppression module which sit's between the two fans at the bottom of the cooling fan houseing. Both fans plug into the module. Many of cooling fan problems have been traced back to that module. As far as I know, you can only buy a new module at the dealer. Our you could see if you could get on from a yard and try it.

Here some info on the cooling fan system that may help you:


Table 1
Fan Operating Mode Conditions - A/C Not Activated
Operating Mode 3.3 Engine 3.5 Engine
Low Speed Fan ON 99C (211F) 104C(219F)
Low Speed Fan OFF 93C(199F) 99C(210F)
High Speed Fan ON 110C(230F) 110C(230F)
High Speed Fan OFF 104C(219F) 150C(221F)

Table 2
Fan Operating Mode Conditions
Operating Mode A/C OFF A/C ON A/C Compressor Pressure
Low Speed Fan ON 210F 210F 1446.57 Kpa (209.8 psi)
Low Speed Fan OFF 199F 199F 861.87 Kpa (125 psi)
High Speed Fan ON 230F 230F 1723.75 Kpa (250 psi)
High Speed Fan OFF 219F 219F 1585.85 Kpa (230 psi)

OPERATION
Radiator fan control is accomplished in two ways. A pressure transducer on the compressor discharge line sends a signal to the powertrain control module (PCM) which will activate the fans. The fans are also turned on by a coolant temperature sensor, which sends a message to the engine controller. The engine controller then sends a signal to the fan relay which in turn switches the coolant fans on.

Switching through the engine controller provides fan control for the following conditions:


Fans will not run during cranking until engine starts, no matter what coolant temperature is.
Fan runs according to chart shown in Table 1 and 2.

CIRCUIT OPERATION
The radiator fan system uses two relays located in the Power Distribution Center (PDC) . One relay is used for LOW speed fan operation and the other is for HIGH speed operation. The Powertrain Control Module (PCM) controls the operation of the relays depending on engine coolant temperature and/or A/C operation.

Power for the coil side of both relays is provided on circuit F18. This circuit is protected by a 10 Amp fuse located in cavity 20 of the junction block. Power for the contact side of the relays is provided on circuit A16. This circuit is protected by a 40 Amp fuse located in cavity D of the PDC.

When LOW speed fan operation is required, the PCM grounds circuit C24. This causes the contacts in the relay to CLOSE connecting circuits A16 and C23. Circuit C23 connects from the relay, and is spliced to the low speed fan motor and the Radio Frequency Interference (RFI) suppression module. Ground for the motor is provided on circuit Z1, which terminates at the left front frame rail.

When HIGH speed fan operation is required the PCM grounds circuit C27. This causes the contacts in the relay to CLOSE connecting circuits A16 and C25. Circuit C25 connects from the relay, and is spliced to the high speed fan motor and the RFI suppression module. Ground for the motor is provided on circuit Z1, which terminates at the left front frame rail.
 

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Oh, here's the part # for the dealer RFI part:

Part # is 04592123 and cost is $45.00
 
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