The Stovebolt Site Forums The Shop Area The Electrical Bay Heater blowing fuses - new resistor?

Hello All,
I have a 1964 Chev Burb, and my heater blows a fuse after running for a short period of time at high.

I have done a search for this topic and came up with many good suggestions that I have tried (check the ground, the wire gauge, fan cage size).

I am still having problems with my heater blowing fuses.
Since I am a novice at a lot of this stuff, I would appreciate some more help.

IF the heater motor was working at different speeds, would this mean the resistor is OK?

I pulled the resistor to check and see if the coils were corroded and saw nothing of concern. Can you tell thru visual inspection if your resistor if gone?

Any other ideas?
Thanks for your time.
Bert.

Bert,

I must have done the same search you did...actually found a post with the same title as this one.

I didn't see any definitive answers, so here are some thoughts. If the heater motor works at all the different selected speeds it means the resistors are OK. The motor should pull more current when it runs at the slower speeds than it does at the higher speed (I think), and you're saying it only blows the fuse when run for awhile at the HI speed.

Does your fuse box indicate what size fuse should be in this circuit (10 amp), and are you using it?

Could there be a restriction in the flow of air passing the motor that might make it heat up when running on HI?

Do you hear any noise from the motor when running in HI that might indicate dry bushings or some mechanical issues with it.

If the fuse is sized properly, the motor would only draw excess current if it were crapping out. This would be my first guess. Your choices would be a intermittent dead short through a wire or bad switch, or a motor that was shorting or pulling excess current when it ran for awhile at max RPM.

I don't know how difficult it is to replace the motor, but aside from this, crawling around under the dash, wiggling wires in a effort to get it to blow a fuse would be worth a try.

If the resistors are contiguous, they are probably fine. Keep us posted.

Stuart

It should use a 30 amp. fuse.

My fuse box was painted by the PO, so nothing is left. The information I have from the manuals, indicated a 10 amp fuse - that was what was in there.

Quote

Could there be a restriction in the flow of air passing the motor that might make it heat up when running on HI?

No, I took the whole heater assembly apart, put a new motor in and cleaned the whole thing, double checked functionality of all levers and paddles, the air flow is fine.

Quote

Do you hear any noise from the motor when running in HI that might indicate dry bushings or some mechanical issues with it.

Just the sound of blowing air ...

Quote

If the fuse is sized properly, the motor would only draw excess current if it were crapping out. This would be my first guess. Your choices would be a intermittent dead short through a wire or bad switch, or a motor that was shorting or pulling excess current when it ran for awhile at max RPM.
Stuart

I will check the fuse information in the manual again. Perhaps I misread it.
The PO put in a new wiring harness under the dash and the wires look new. I will do the wiggle test to see if there is something broken.

Thanks for all your suggestions.
Bert.

Thanks Wrenchbender, I will try this change and see whether it works.
Bert.

Bert,

All the sites I visited show a 10 amp fuse too. Things are a little more complex....someone snuck in a new motor and wiring!

The interesting thing is that your post indicates the motor will run on high for awhile before it pops the fuse. This sure is indicative of a undersized fuse that is merely taking its time to overload and pop.

Improper wiring would usually result in a instant short. What does the motor do on LOW, or if there is one, a medium speed. Is it only the high speed that kills the fuse?

There was mention of an incorrect fan assembly in one of the posts I searched. If the motor were run at HI, and couldn't move the air properly, it would tend to load the motor and make it draw more current.

If wire size was adequate, sticking a 15 amp fuse in would be a interesting experiment. If this fuse blew too, but after a longer period of time, you would definitely have to find the problem. If wire size was adequate for 15 amps, and this larger fuse solved the problem, you would have found your solution.

Could the replacement motor you installed have had a higher current draw than the stock motor, thereby neccesitating a larger fuse?

Stuart

Yeah I guess I should have indicated that up front sorry.

Quote

Is it only the high speed that kills the fuse?

Yes it was only on high that it blew the fuse.

Quote

If wire size was adequate, sticking a 15 amp fuse in would be a interesting experiment. If this fuse blew too, but after a longer period of time, you would definitely have to find the problem. If wire size was adequate for 15 amps, and this larger fuse solved the problem, you would have found your solution.

And so it was - 15 amp fuse and heater runs on high with no problems.
Must be as you suggested,that the motor they gave me was a different draw. perhaps it was one that fits the newer model trucks as well.
It was identical mounting and connection.

Thanks for all your help Stuart.
Now it is on to the horn...
I really want to get this thing registered soI can drive it!
Bert.

Hello All,
thanks for the previous help.
Trying to sort out the next stage of heater problems.

I ended up having to use a 30 amp fuse due to the draw of the newer heater motor, I thought I was goodto go and did for many weeks, but I seem to have some wiring gremlins.

So first I would like to find out where this wire that has broken off should connect.

It is the red wire connected to the top left terminal (parallel to the heater fuse) in the 64 fuse panel, which in Jolly's diagram is indicated as "IGN.unfused"

This wire broke off and shorted out my tails lights and heater.

Now I would like to get it hooked back up so that I can go back to cruising with heat temporarily until I get a new wiring harness.

Does anyone have any ideas where this should be going to?
I have the wiring diagrams and they are not helping me.
I was thinking this was the power to the heater, but I am currently at a loss as to where it fits into the spaghetti.

Thanks for your time.
Bert.

Bert,

I looked at Jolly's site but can't seem to find the right diagram. If you feel the wire is actually "IGN-unfused", that would indicate it is switched on and off with the key, but not supplied with protection. Was this obvious to you already...

Does the fuse block on your '64 have notations next to the fuse holders. I have seen fuse blocks that had several terminals that were energized with the key and not fused. They accepted push on terminals and were intended for owner add on's I think.

I guess I would ask, what doesn't work with the red wire dangling?

Stuart

I thought it was Jolly's,but Icannot find ti there either sorry for the misdirect

Yes this was obvious- I am learning slowly ...:0

These are the terminals in question,and the wire is attached with a push on terminal and terminates in a broken off wire at the other end.

The heater ...

I am sorry if that was not obvious from my earlier post. This is why I am stumped. In the diagrams that I have regarding the heater, it shows the wiring coming from the opposite end of the fuse. I thought that the power to these fused elements cameinto the fuse block from the power wire in the back of the block- but perhapsI am wrong and the power for this fuse comes from the broken red wire. My problem is that thisbroken red wire should not be hot if it is the power wire from the ignition swith,yet it sparks when it hits ground.... so?

it is late as usual and I am rambling - more details tomorrow or monday once my son is back home.

Bert,

I have linked a diagram for a heater and associated wiring. It is for a '65 GMC...maybe there are similarities between this setup and yours. It's worth a look.

Stuart

http://rides.webshots.com/photo/1546203618046814442HwgfJw