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

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

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"?

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.

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?

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.

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

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.

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.

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

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.

CHECK MAIN GROUND on the battery and cables.

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.

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!!!

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

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!

99% of all electrical problems are linked to a faulty ground. Think about the way a switch works.........doesn't a switch ground out and/or completes the circuit? Don't have my wiring diagrams nearby but I bet if you looked you would see how the fan switch will complete the ground (circuit)- that is when it works properly..............You mentioned the blower motor comes on only when you put the switch on high, mine was doing the same thing. Have you ever tried jigglling the switch around to make the proper contact to make the blower motor operate at a lowerer setting? I would have to "play" w/my switch for awhile to get it to a lower setting when desired. One last question...when switch is in the off position, and you have the AC button pressed in, does the AC button light remain on??? Try that, I know you said your in Michigan where you may never even use the AC but I'm from Texas and thats how I figured out it was my switch because I knew that when the fan switch is in OFF position, the AC button light (indicator) should not remain lit. When AC is selected, indicating light should only light up when you turn the fan on. Try that if you haven't already. I'm telling you it took me a little while to figure out that even though the switch is off and you can't hear the blower, the unwanted annoying air flow was due to the faulty fan switch and as mentioned, this is a very common thing. Let me know.....

Well I just went out and checked to see if the AC light stayed on or turned off after I turned off the fan. When I turned the fan to the off position the AC light turned off as it's supposed to. So I may be sticking with my theory about a bad ground, I just wish I knew which contact it is. I have a Haynes manual but It just tells what is grounded in a wiring diagram, it doesn't give exact locations. So perhaps I will search and destroy!!!

Alright, your problem must be different than what I experienced. Got some locations you can check perhaps. But what I'm wondering is why and/or how do you have a loose/bad ground to your blower motor? Reason I ask is because if you have had any work done on your truck that would involve get under the dash a little, than I wold suspect that there might be loose wire near the location of where work was done. Anyways, if you remove your glovebox I think there are about 3 or 4 wires screwed into the metal frame for the dash. Then there is like 2 to 3 wires underneath steering wheel/fuses area. I would scope out behind the glove box, that might get you started, if you hadn't already. To remove glove box you simply grab the little tab on the plastic strap on the left hand side, push glovebox back a little until plastic strap discvonnects, then carefullylet box down beyond its normal open position and pull until it pops off. Real easy. Once you get in there, you will find basically all the AC/heat stuff including wiring. Hopefully that helps you out more!

I have had my dash apart for a CD player installation, but that was years ago. I'm going to tear it all up starting tomorrow if I don't get held up to long at class. I will keep you posted and let you know if I have or have not found anything. Thanks for the help!!!

I have had my dash apart for a CD player installation, but that was years ago. I'm going to tear it all up starting tomorrow if I don't get held up to long at class. I will keep you posted and let you know if I have or have not found anything. Thanks for the help!!!

Even though it was a few years ago, if you did possibly knock something loose it could possibly just now start acting up. But if all you did was a CD player than I doubt anything got knocked loose; wrong location. if you have never seen behind youre glove box, that is definantly I would suggest looking and chasing wires. Good luck, keep me posted

check your body grounds as well

engine to firewall
battery to fender

Alright guys finished it all up. The problem was perhaps multiple problems ground, switch, etc. After checking all available grounds, fuses, and switches, the problem seemed to be fixed after i put a new fan speed switch on. It's hard to say whether or not that was my problem in the beginning, but oh well it's fixed! Thanks Again for all your help!!!

damn, I think I suggested it was the fan switch! Glad to hear you got it though