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Old 07-04-2018, 04:35 AM   #2
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 43,465
 

2003 L-Series 3.0L Sedan
Default Re: A/C fan not working.

Are you describing the ac blower fan inside the car or the radiator/ac condenser cooling fan? Each fan has it's own circuit, downstream of the engine computer, ecm. Without more info, my initial guess is this dealer may be attempting to emptying your wallet. Fans have fuses and some use a relay. Fans are controlled by circuits. Engine cooling fan(s) use the same circuit whether or not its for overheating coolant or using ac. Every ac system turns on cooking fan - the ac condenser coil gets hot and it's in front of the radiator. Without the fan running when ac is used, hot air from the condenser coil flows into the radiator that's already hot and can result in overheating. Cooling system and ac suffers if the cooling fan doesn't run. Without ac the cooling fan runs only when coolant reaches a temperature the engine computer determines warm enough to turn on. The cooling fan operates on the same circuit for either the ac system demands it or when engine coolant demands it.

Fuse, relay or faulty fan may be the problem and not the ecm. You're always free to try another dealer or reputable auto electric shop experienced in electrical systems. Some may even be knowledgeable about engine computers in general to make honest assessments.

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