Off topic for jeep forum

nursecosmo · **Posted:** Mon Jan 05, 2009 1:45 am

I have posted this question on a couple of truck forums without a helpful response, maybe someone here knows the answer seeing as how we have all proven ourselves to be above average students when we purchased our CRD's.

I have a weird blower motor problem in my 97 Dodge Ram. when the temp drops below 15 degrees or so, the heater fan won't function. It doesn't always do it but seems to be getting worse. I can jiggle the selector switch with no joy. I have examined the resistor but see no external sign of failure. When it won't blow, it won't blow on any speed which leads me to believe that it is not the resistor. The fan turns freely and when malfunctioning I can thump on the side of the motor and it still won't go. When I bring the truck into a warm shop to work on it the problem goes away and the idea of poking around under the dash with a test light in the freezing wind is not attractive to a wimp like me. Needless to say, when the temp drops into the -0s I am hurting. The biggest problem is that my interior window glass ices up.

Does anyone have a clue on this one? Has anyone ever seen a resistor go bad intermittently at all fan speeds?

Joe Romas · **Posted:** Mon Jan 05, 2009 7:25 am

I'll bet the blower motor's bearings are freezing up :lol:

Does it "grawl" sometimes too :?:

moto-scoot · **Posted:** Mon Jan 05, 2009 9:34 am

pull blower resistor connector check for melted terminals
sign of excessive blower motor draw
there is a repair connector available from mopar.
the bad news is if connector melted you need everything
connector resistor & blower motor

moto-scoot · **Posted:** Mon Jan 05, 2009 9:46 am

Ive just changed connector & resistor
vehicle usally is back within a year
with same problem.
mopar blower motors dont blow fuses for some reason
so you have to change motor to correct excessive draw
which fries connector & resistor

nursecosmo · **Posted:** Mon Jan 05, 2009 12:16 pm

Joe Romas wrote:

I'll bet the blower motor's bearings are freezing up :lol:

Does it "grawl" sometimes too :?:

No, it doesn't give any indication of seizing. It spins freely.

gmctd · **Posted:** Mon Jan 05, 2009 12:16 pm

May be difficult to imagine, but that '97 Dodge has gotten mighty long in the tooth, here in 2009 - disconnect the Dodge connector, use a jumper wire from the battery (+) to the motor connector - that will tell the tale, in reader's digest condensed form.........

nursecosmo · **Posted:** Mon Jan 05, 2009 12:18 pm

moto-scoot wrote:

pull blower resistor connector check for melted terminals
sign of excessive blower motor draw
there is a repair connector available from mopar.
the bad news is if connector melted you need everything
connector resistor & blower motor

No, as I posted there is no sign of damage on the resistor or terminals.

nursecosmo · **Posted:** Mon Jan 05, 2009 12:21 pm

gmctd wrote:

Disconnect the Dodge connector, use a jumper wire from the battery (+) to the motor connector - that will tell the tale, in reader's digest condensed form.........

Thanks GM, I will try that when it warms up today. It was -8 this morning.

gmctd · **Posted:** Mon Jan 05, 2009 1:23 pm

Holy cow!! - we're shivering here in Texas at 45*, wind chill is 40*................

vtdog · **Joined:** Fri Sep 30, 2005 11:27 am **Posts:** 640

I had a similar problem in a Pontiac that was my work issued car. Turns out the screw holding the ground wire for the blower was loose. In very cold weather there was enough "'shrinkage" in the wire to pull out the wire just enough to reduce contact with the ground screw. Tightening the screw down fixed the problem.

nursecosmo · **Posted:** Mon Jan 05, 2009 8:01 pm

gmctd wrote:

Holy cow!! - we're shivering here in Texas at 45*, wind chill is 40*................

Ha ha, rub it in GM.

Thanks to everyone for all the suggestions. I tried jumping the fan this afternoon but got no joy. So then I checked the power lines starting at the fan feed wires. Hit pay dirt on the first time. There is power all the way from the switch to the fan but the fan wont spin. So I have discovered where the problem lies. The good thing about the fan being bad is that it is the cheapest component to replace. The nearest thing that I can figure is that the brushes in the fan are worn to point that when the armature gets cold it contracts so much that the brushes can't touch anymore. Thanks again.

nursecosmo · **Posted:** Sun Jan 11, 2009 8:01 am

nursecosmo wrote:

gmctd wrote:

Holy cow!! - we're shivering here in Texas at 45*, wind chill is 40*................

Ha ha, rub it in GM.

Thanks to everyone for all the suggestions. I tried jumping the fan this afternoon but got no joy. So then I checked the power lines starting at the fan feed wires. Hit pay dirt on the first time. There is power all the way from the switch to the fan but the fan wont spin. So I have discovered where the problem lies. The good thing about the fan being bad is that it is the cheapest component to replace. The nearest thing that I can figure is that the brushes in the fan are worn to point that when the armature gets cold it contracts so much that the brushes can't touch anymore. Thanks again.

Nope I was totally wrong. The fan motor is just fine. I finally found it, there was a relay coming from the ignition which was unlisted in the manual which I happened to find by accident up under the dash. The ignition relay supply wire was loose and causing the relay to cut power to the whole system. The strange thing about the blower fan circuit is that the switch and resistor go backwards from the fan and are supplied by ground instead of + . so when I tried jumping directly to the switch or resistor with a hot wire nothing would happen. Also the energizer relay connects both hot and ground. I can't imagine why it would need to disconnect both wires when the ignition is turned off but it does.

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