The Stovebolt Site Forums The Shop Area The Electrical Bay Heater Blower Question

My old blower kept popping the fuse and although not frozen, I thought it was time to replace it. It moaned and groaned and made a lot of noise. I put in a new blower and fuse, I believe 20 amp. The new blower seems to run great.
Days later my truck would run and then just die unexpectedly. Sometimes it wouldn't start. It wouldn't keep cranking and cranking, it just wouldn't start. Then sometimes it would. I have been pulling my hair out trying to figure out what is wrong with my truck. Then today I think it hit me. As I was driving down the street with my heater "on", my truck just died again. Turned heater off and started right up and came home. Ran her in the driveway, then turned the heater on and simotaneusly the truck died.
I guess my question is what gives? Does the blower require a ground? Could wrong fuse be doing it? Something shorting out?
My motor/carb is in EXCELLENT condition, turn key start everytime, ran flawless before this.
I am running an HEI distributor.
Any help would be great. Thanks!

Did you replace the wire from the ignition switch to the HEI when you upgraded to the electronic ignition? Depending on the year of your truck, there will either be a ceramic resistor on the firewall, or a nickel-chrome wire from the ignition switch to the original coil. Either way, the voltage to the coil would have been dropped to about 9 volts at the coil + terminal to prevent burning the points. The HEI needs full alternator voltage, about 14 V, to work right, and also a lot of amperage. The best bet is to run a #10 wire all the way from the ignition switch to the HEI coil's + terminal, and eliminate the small-gauge wire to the resistor, or the nichrome wire. It sounds like the heater blower is robbing voltage from the HEI, and the only way that can happen is if the wiring to the ignition switch from the battery, or the wire from the switch to the HEI is too small to carry the current load, or it's dropping the voltage available to the electronic ignition.
Jerry

thank you for your help!
the previous owner didn't do much to this truck at all, but one of the things he did was install a new wiring harness. Kind of a generic one, but nonetheless new. I believe the new wiring harness was "made" for an HEI and also internally regulated alternator. Basically, the harness just plugs into the hei, and the wires appear to be new.
I guess where I am confused is how the heater is "tied" into the ignition?
I am pretty comfortable in all aspects of these old trucks except one area...electrical! drives me crazy!
thanks again for your help. I am going to crawl under the dash tomorrow and do some more investigation.

Maybe isolate the heater from the rest of the system,go from battery to a switch to the heater?

I'm guessing it's a bad electrical connection somewhere and I agree with PapaJ. Isolate the two systems. It might be easier to temporarily run a #10 wire directly from the battery to the coil, and then try your heater. If this solves the problem, you know its a bad wire or bad connection under the dash. I had a similar problem with HEI and it turned out to be a bad ignition switch. Current for both the heater and the coil run through the ignition switch.

I replied to the same question in the 60-66 section.

Would there be any advantages to putting a relay on the heater? I am having a similar problem with my new heater motor blowing the fuse when I turn it on. sometimes it runs for a few seconds but always blows the fuse. 1953 Chevy with all new painless wiring.

Once again the stovebolters came through for me. I investigated it further today. After a good nights sleep and a cool head I checked everything under the hood. Perfect....so I went on to under the dash. When I started inspecting the ignition switch, I noticed the pink wire was barely clipped into the ignition switch. As you guys know, the wires go into a black plastic plug, then the plug snaps into the back of the ignition switch. The pink wire was basically falling out of the plug. So, I took her completely out, rebent her a bit, snapped her back into the hard black plastic plug, smeared a little di-electric grease on to the ignition switch, then snapped the plug onto the ignition switch. Whooppeee! I don't want to get to confident yet, but drove her all day and no problems. Also, while running I put a meter on the posts with the heater running and pulled about 14.5 bolts! I think I caused this problem myself, because when I put the new blower in I also installed some new vent tubes under the dash. In wrestling these things, I probably banged some things around under there. Rookie mistake.
Anyways, thanks to all who through in their 2 cents, I will let you know if this is the fix. keeping my fingers crossed.
On another note, my blower also blows the 10 amp fuse consistently. It is a new Thriftmaster. I popped in a 15 amp today and so far so good!