Ignition....is it all related???

[JVis21]

Hey guys I have a 1996 Chevy 1500 350 4X4. Recently my blower motor has been deciding on its own when it wants to blow some heat on me. It only works occasionally but only on high. I've replaced the resistor card, blower motor itself, and the relay and still nothing. I've used a voltage tester on the two wires that feed the blower and they are hot only until I hook them up to the blower motor. Perhaps in a related situation I walked out to my truck and went to start it but everything seemed to be dead. I waited for a while, and my dome light clicked on and I was able to start my truck.
Could this all be related through my ignition switch?
Being in Michigan my driving is pretty cold without heat, so any suggestions would be great!!! Thanks

[planedude]

check your battery terminals for corrosion. also check the ground for the blower. What setting is the heater set at when "it decides to blow"?

[planedude]

if there is anything drawing power left on or working after you shut off the truck 45 minutes later it will shut off the main feed. just a battery saving thing. So I would say there is something being powered after you shut it off. Start pullling fuses till it doesn't happen.

[J-Ri]

Was the time you had to wait for the power to come on a single occourance, or does it do that regularly?

You said "It only works occasionally but only on high". Does it only come on when the switch is on high, or will it come on at any position, but the speed is at high?

Also, do you know if the resistors are on the battery or ground side of the motor?

[JVis21]

The heater only turns on when the switch is in the high position, if you try adjusting it after it comes on it will die again. The it could be 30 seconds or 30 mins before it comes back on, but again only on high. As for the when I did replace everything it worked for a day fine, then right back to it's old ways. I can't hear or feel the relay switch making any clicks or movements, so I'm wondering if my ignition switch could be destroying my relays.

[JVis21]

J-Ri, I've had to wait a couple times for the power to come back to my truck, the blower comes on only when the switch is on high (the blower is at high speed also), and the resistors I believe are on the battery side of the motor. Thanks Again

[planedude]

Have you measured the voltage on the plug for the motor to see if it is actually 0. When you disconnect your battery does it seem like there is alot of current(spark) when you touch it back on. Its seems to me there is something staying on after you leave, and its prob related to your blower issue.

[JVis21]

I think the battery is fine because soon as the power comes back the gauge reads a good voltage, if something were staying on and draining it I don't think I would have enough juice to start my truck.

[planedude]

Thats what the feature is for to save your battery if there is a drain on it. I have the exact same truck.

[J-Ri]

I'd say it's most likely a problem with the switch for the blower motor. The next time the motor doesn't come on, check to see if there's any voltage at the connector. You could also hook jumper wires up to the conector and see if the motor comes on. I'm not too familiar with the newer trucks, but on my 86, these checks would be very easy to do.

[Fireplug]

CHECK MAIN GROUND on the battery and cables.

[JVis21]

I did run a hot wire directly from the battery and the motor seemed to be working fine. The The contacts read a good voltage until i hook them to the motor. It's almost as if as soon as there is a load (the blower) the power is lost.

[JVis21]

OK guys I've narrowed it down!!!! haha I ran a ground directly from the battery and the blower seemed to work. Ultimately that means I have a bad ground, any suggestions on where to start??? Thanks Again for all your help!!!

[Cadillakin'98]

The blower motor thing sound like something my "98 was doing. To make sure I understand your ? correctly, even with the AC/heater fan switch in the OFF position, do you still feel air blowing? If so does it feel like it is blowing at a slower rate than your lowest setting on switch normally? And if you switch to different vents do you feel air blowing while in OFF postion? These are things I was noticing awille back and I remember noticing the air flow more when my switch was set to the floor board vents (like when you have the heater on). Anyways, if this is what you are experiencing than I can tell you it is most likely to be your fan switch. Turns out this is a very common problem on say '94 to '98 (maybe even earlier) models. Your aC/heater controls should be a set of three switches located just below radio - 1 for fan, 1 for temp, and 1 for vents. Beware that when you go to dealership to get a new switch, many parts advisors while try saying you have to replace the whole assembly of 3 (roughly $150) but you can by just the one fan switch individually and its fairly simple to replade. I don't quite follow or understand your other problem(s) described; sorry I can't help you there but good luck

[JVis21]

Thanks Cadillakin for the advice, I believe that all my problems are simply caused by a faulty ground. If the problem continues I may have to look into the switches in the dash. Like I said running a straight ground from the battery seemed to work so any help with the locations of the grounds would be great!