Glad it's working, but as mentioned before, the voltage drop across both halves of the circuit is going to be the same, so unless you're got a better or more direct path to ground with the new setup, it's functionally identical. You're still passing the same amount of current through the fan motor and the resistor leg, so there should be no change.

Did you ever try the TSB fix for the heater core electrolysis I posted a while back?

-Joe

 

Joe,

Its the static discharge from the fans when you turn off the engine that need to fing a more direct path to ground. I did the TSB back about 2 cores ago. A friend was rewiring a hotrod 99 Camero so I looked up how GM was wiring their blower motors and they have the resistor pack on the positive side of the motor. Never heard of them blowing heater cores......

JMC

 

What would make you think that there is a static charge building up, and if there was, wouldn't there also be a shorter path to ground if it jumped to the blower motor case and mount?

Another thought: If that was happening, wouldn't a set of copper 'brushes' rubbing the squirrel cage pull the charge off the plastic before it built up enough to jump? (in my mind, I'm seeing the fanned-out copper wires that pick the charge up off the rubber belt in a VanDeGraff Generator) Those resistors are no contest for a static charge.... were there a static charge building up on the squirrel cage, wouldn't it want to jump to the steel motor shaft that it's connected to?

I'll be surprised if this works any better than the OEM setup. I guess time will tell, huh?

-Joe

 

Double post ???????????

 

Static discharge looks for the path of least resistance to ground. Remember the core is insulated inside the plenum and so is the blower motor. Where does the discharge go? Jump to core travel through coolant to ground. The second and only other path of choice is to travel through the resistor pack. Wiring it my way the path of least resistance is to travel through the shaft straight to ground. If you ground the OEM wired Blower motor it will either run on high all the time or blow the fuse.
JMC

 

OK, so here's the million dollar question: How come yours has blown 8, but mine's still on the original?

-Joe

 

I don't know Joe. How come some Tritons spit plugs while others don't? I have read about failures on CorwnVics and on a few Expeditions too. Why does Ford have a procedure for heater core failures if they are a rare occurance?

JMC

 

I wasn't insinuating anything by the question, just thinking out loud. There's obviously a problem there, hence the TSB, and I'm not implying anything different.... just thinking out loud, that's all.

The point of my question wasn't clear.... Take two trucks (yours and mine). They rolled off the same assembly line around the same time. I'm wondering what applicable differences there may be that cause your cores to fail so rapidly where mine (and many others) lasts much, much longer?

Another thought.... what does the blower motor physically mount to? Having never had mine apart, I've never seen the plenum..... isn't the flange that the motor mounts to metal?

 

Joe,

I realize that now that you are thinking out loud. Sorry if I came off a little harsh. Trying to solve this situation is frustrating. One positive thing about this is one of the local shops will farm out the heater cores to me. What has me confused is even with the engine swap from the 4.6 to the 5.4 did not stop the cores from blowing. I was kind of hoping that the higher reving (6500 rpm) 4.6 might have been the culprit. The 5.4 is set at 5700 rpm. I did use some of the 4.6 accessories and the water pump was one of them. Maybe the pump had a role to play in all of this? It was changed a few days ago.

The blower motor is mounted in plastic so the only path to ground is through the ground wire.

JMC