A/C Fan not working

[MattKeller]

I have a 2003 Dodge 2500 with the 5.9 Cummins and 6 speed transmission. The heater and A/C fan isn't working and my truck is spitting out the codes P0541 and P2607 which are low voltage at the #1 and #2 intake heater relays. Any idea how i can fix my truck? Winter is approaching and I would sure like to get this resolved soon. Let me know if you need more information.

Thanks

 

[jhenderson]

I doubt the 2 are connected. Check for voltage at the plug for the fan. It's under the dash on the passenger side. If it's got 12 volts try hitting the fan motor with your hand. If it doesn't run the fan is shot.

 

[PWong]

The heater and A/C fan isn't working and my truck is spitting out the codes P0541 and P2607 which are low voltage at the #1 and #2 intake heater relays

For the blower: check blower motor & blower resistor if you have 12V at the connector on the resistor. (Disconnect connector first).
check ignition switch if you don't have 12V at the connector on the resistor.
For codes: check power and ground to relay coils and power output to heaters from relays.

 

[MattKeller]

For the blower: check blower motor & blower resistor if you have 12V at the connector on the resistor. (Disconnect connector first).
check ignition switch if you don't have 12V at the connector on the resistor.
For codes: check power and ground to relay coils and power output to heaters from relays.

I checked the voltage and after reading this I realized I checked the voltage at the connector on the blower motor and it was giving me 12 volts. I didn't check the resistor, does it matter which I check? Anyhow, I replaced the blower motor and still no luck. Any more suggestions? Could it be the relay?

 

[PWong]

I checked the voltage and after reading this I realized I checked the voltage at the connector on the blower motor and it was giving me 12 volts. I didn't check the resistor, does it matter which I check? Anyhow, I replaced the blower motor and still no luck. Any more suggestions? Could it be the relay?

Check resistor on blower housing. Power goes to motor then to resistor then to selector switch then to ground if IIRC.
I don't have the wiring diagram with me now. Will confirm that tomorrow.

 

[MattKeller]

Check resistor on blower housing. Power goes to motor then to resistor then to selector switch then to ground.

I did take the resistor out and look at it, everything looked to be intact and in good working order. I will check the voltage on the connector to the resistor this evening to see if it is putting out 12 volts. If that is not receiving 12 volts then it would be the ignition switch that is acting up? And if it is receiving 12 volts, what is the next thing to check?

 

[PWong]

Will confirm the circuit tomorrow morning.

 

[jhenderson]

The resistor varies the voltage to the blower motor. If you have 12 volts at the blower, the motor is bad.

 

[MattKeller]

The resistor varies the voltage to the blower motor. If you have 12 volts at the blower, the motor is bad.

I'm lost then, because I checked the voltage at the blower motor, it came up with 12 volts so I tried changing the blower motor and it still doesn't work. Do you think it could possibly be the switch for the fan? This is getting frustrating

 

[jhenderson]

It could be. As far as I know the ground is switched not the +. That lessens the load on wiring and switches. Use your test light to check the ground wire in the plug. As for the resistor; when they fail you usually loose lower speeds on the fan circuit. When the resistor fails it can't reduce the voltage.

 

[PWong]

Don't want to tell you exactly what to do until I have the diagram in front of me tomorrow morning.
If you don't have any blower speed at all and you have a good motor then it's the selector switch or the ground.
Will tell you how to test it tomorrow.

 

[PWong]

http://www.dodge.com/bodybuilder/2005sbbgl/docs/wd/dr/wiringdiagrams/8w42airconditioning.pdf
Please refer to page 2/10. I don't have diagram for 2003 and assuming it's the same as 2005.
Key ON, disconnect connector from the resistor block and check the connector wiring with a voltmeter.
Should read battery voltage on EACH wire if the ignition switch and the motor and the resistor are all good.
If ALL have zero volt then you have ignition switch or motor issue.
If at least one (but NOT ALL) wire has zero volt then your resistor block is BAD.
If ALL have battery volt, use a jumper and jump each wire to ground, one at a time, the motor should run at different speed.
At this moment you proved every thing was good except the selector switch.