Blower fan won't come on

electrical-wiring
engines
blower-motors
fans

#1

2004 Dodge Ram 3500 5.9 Diesel



The blower fan for the AC and Heater has stopped working. At first (the last 3-4 months) it was intermitent, coming on and going off. But now it won’t come on at all. The motor never made any noises or suggested that the motor was having any trouble.



Could it be the switch? A relay? If so where are the relays in this truck? I looked around and didn’t see any loose wires and the fuse is fine~


#2

[b]When a blower motor turns off and on intermintently, and then fails to operate altogether, it usually means the blower motor has given up the ghost.

Out of all the vehicles I’ve seen that displyed this symtom, 99% of the time it was because of a defective blower motor.

Tester[/b]


#3

Even thought it’s only a few years old? The last time I had a blower fan go out was in my '70 Chevelle. and to be honest it made a horrible noise for about a year before it finally gave up. I thought a blower motor issue would mean that the motor would give some sign of strein first, That’s why I was thinking this might be a relay. Is there a good way to test the motor with out having to completely remove it from the truck? Thank you


#4

It seems too early for the blower fan to go out but it sure could be a problem. You can apply 12 volts directly to the blower and see if it checks out. The relay may be in the power panel under the hood.


#5

Check for voltage at the motor. Make sure the fan can freely move.
Is the thermostat analog (dials and no display) or digital (buttons and a display)?


#6

Tap on the blower motor with a rubber mallet. I had a similar problem with a Ford Aerostar. The motor would quit for a while and then come back on. I could restart the motor by opening and slamming the hood. As the others have suggested, check to see if you are getting power to the motor. If so, it’s the motor. If not, you might run a lead directly from the battery to the motor. If it comes on, the problem is in the switch or wiring. Just test it–don’t make the connection permanent.


#7

it’s an analog switch.

And thank you to everyone who has replied.

is there any way to test the relay if the motor turns out to be ok? or will I just have to buy a new one?


#8

At the motor, simply connect a voltmeter in parallel and check for voltage. Or disconnect the motor from the circuit and connect a known good power supply to it.
Relays are cheap so it’s often easier to just replace them. They can be tested with a power supply and ohmmeter if you know the pinout. More elaborate equipment is needed to check if the contacts are actually good, at which point you might as well just replace the relay. Replace it with a relay of higher current rating so it lasts longer.