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HDGENE, ASE Master Tech
Category: Dodge
Satisfied Customers: 4782
Experience:  25 years Auto experience, Ford, GM, Chrysler, Asian & European
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The condenser cooling fans are not coming on when I turn the

Customer Question

The condenser cooling fans are not coming on when I turn the AC system on I have checked the fans and there's nothing wrong with that
JA: OK. What is the model/year of your Dodge?
Customer: 2008 Dodge Avenger RT model 3.5 engine
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I think I can fix it myself but I would like to know what turns off and on when you turn on the AC that's probably what's bad
JA: Anything else you think the mechanic should know?
Customer: Don't think so
Submitted: 2 months ago.
Category: Dodge
Expert:  HDGENE replied 2 months ago.

Hello, when you turn the ac system on, the compressor engages? Do the fans come on when the engine reaches normal operating temperature with the ac off? No warning lights on? If you apply power and ground to the fans will they operate?

Customer: replied 2 months ago.
The fans come on when the operating temperature is reached also the air conditioning compressor comes on when I turn it on it that's always functioning properly that's about it
Customer: replied 2 months ago.
I did apply apply power to the fans at both their speeds and it worked great with a jumper
Expert:  HDGENE replied 2 months ago.


Fan control is accomplished three ways. The fan runs when the air conditioning pressure reaches a set pressure, refer to RADIATOR FAN OPERATION chart. In addition to this control, the fan is turned on by the temperature of the coolant which is sensed by the coolant temperature sensor which sends the message to the Powertrain Control Module (PCM). The PCM turns on the fan through a fan relay. On models equipped with automatic transmission, a transmission fluid thermister may have some influences on fan operation. See Wiring Diagrams Manual for circuity and diagnostics provided.

The Powertrain Control Module (PCM) provides fan control for the following conditions:

  • The fan will not run during cranking until the engine starts no matter what the coolant temperature is.
  • Fan will run when the air conditioning clutch is engaged, and once set compressor head pressure is reached.
  • Fan will run according to the following information charts.

it doesnt list a chart for the 3.5 engine, the pcm controls the operation of the low and high speed fan operation. Since the fans do operate on their own for engine temperature, A diagnostic check for codes with a scan tool should be done to see if there is a fault with an ac pressure sensor or ac input fault. If the scan tool can look at live sensor data, it can be used to see if the ac demand is showing that it is on to tell the pcm to operate the fans and if the fans are being commanded on or not. If it is being commaned, then it would be a question if it is a low or high fan speed that is not working and which relay to check which operate the fan speed.

Customer: replied 2 months ago.
I swapped out all the relays it's not the relays
Expert:  HDGENE replied 2 months ago.

Then it has to be an issue with the PCM control of the fan system. A diagnostic scan tool would be needed to check for codes and see if you can command the fans on using the scan tool to eliminate a wiring issue or other control system fault.

Expert:  HDGENE replied 2 months ago.

Do you need more help with this concern?

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