Protecting your blower motor switch (non-EATC)

Topic: Protecting your blower motor switch (non-EATC) (Read 8255 times) previous topic - next topic

Protecting your blower motor switch (non-EATC)

Reply #15 – August 12, 2012, 08:42:32 PM

yea, your catching power upstream of the blower motor which is more electrically correct.
this was a little tricky to think through with a single relay, my hats off to you!!.... i sat here for 45min trying to figure out how to control that high speed ground lead then it hit me,,, "eye don need no stinkin grownd down theyr"

Protecting your blower motor switch (non-EATC)

Reply #16 – August 12, 2012, 08:45:13 PM

LOL,, see, they did what i did, they are powering the relay downstream of the motor.
I like your first version, now why is your first version not a good choice?>

Protecting your blower motor switch (non-EATC)

Reply #17 – August 12, 2012, 08:52:48 PM

looking at your revision, and granted there are several ways to do this,,, dont you think they went the long way around the track? i just traced it out and it makes a complete circle back into the coil which then the relay coil picks the very same ground the contacts are picking.

interesting but im dizzy

Protecting your blower motor switch (non-EATC)

Reply #18 – August 12, 2012, 08:57:04 PM

I think my point is "what will work" is what the attempt is here..... not "what did you do" to get it to work.
Granted the layout above on post 15 works,,,
What is the benefit and how is it different from your deleted solution and the one i have posted?

Protecting your blower motor switch (non-EATC)

Reply #19 – August 12, 2012, 09:01:51 PM

another interesting thing, once you select "HIGH", that allows the blower coil to energize but in effect the "HIGH" contact now becomes open as the relay has latched to the secondary path. They are also basically deleting the ground leg off pin1 of the switch but using it for the time it takes to prime the coil only.

Protecting your blower motor switch (non-EATC)

Reply #20 – August 12, 2012, 09:24:03 PM

Perhaps I am confused, but in one of these revisions, the secondary (bottom) relay in the closed position removes the needed ground from the blower motor completely, while in another, direct ground is applied to the fused (30A) source through the primary relay. quietleaf's last post however, appears to be exactly what is necessary to protect the blower switch in high from over current, but still relies on the thermal limiter for the low and medium positions, as originally designed. Exactly how much protection the switch really has with so little resistance can only be determined by actually measuring the current when the the blower is in operation at these two remaining levels.

Protecting your blower motor switch (non-EATC)

Reply #21 – August 12, 2012, 09:33:04 PM

Here's my final one, cleaned up...

Protecting your blower motor switch (non-EATC)

Reply #22 – August 12, 2012, 09:38:54 PM

Here's my final one, cleaned up...

Protecting your blower motor switch (non-EATC)

Reply #23 – August 12, 2012, 09:50:04 PM

Yes indeed, this revision will work fine. Do you have a ford part number for the "high speed relay" or will any Bosch compatible 30A relay work? Also, does anyone have a source for new connectors or connector pigtails and pins?

Protecting your blower motor switch (non-EATC)

Reply #24 – August 12, 2012, 09:52:08 PM

Slave relays are used to control high current applications. Most every switch in early fords suffered this dilemma. That is why so many of them found their way to the JUNK YARD as they burned to the ground. Over the years i have slaved out the headlights the fog lights the MFS. the blower motor and absolutely the IGNITION SWITCH. The stock wiring is heavy enough to handle the loads. But the switches are not as good and they get hot and melt. Not only the device the plug also. I have checked current flow through the ignition switch and it can exceed 50 AMPS. Basically just about all the heavy current draw switches have to be slaved. This is a pain to someone that lacks electrical knowledge. But never the less it has to be dun. Sooner or later the switches will melt. Slave relays can handle the loads quite well and are very common today on modern cars. learn how to wire them and you will be saving your ride from a possible melt down.

Fog light plug. Burnt pretty bad. I see so many of these .

All connections must be crimpedand soldered for a good connection. Below is a low high beam relay mod!!

Protecting your blower motor switch (non-EATC)

Reply #25 – August 12, 2012, 09:53:59 PM

Great advice Tom, thank you.

Protecting your blower motor switch (non-EATC)

Reply #26 – August 12, 2012, 09:59:26 PM

88 try this

http://www.repairconnector.com/

Protecting your blower motor switch (non-EATC)

Reply #27 – August 13, 2012, 08:12:37 AM

hey tom,
pls comment on the blower slave relay for both my design and quietleaf's layout.
wanna get these over to eric for a coolcats adder when reviewed and approved.

Protecting your blower motor switch (non-EATC)

Reply #28 – August 13, 2012, 08:45:53 AM

Quote from: Crazy88;395839

Perhaps I am confused, but in one of these revisions, the secondary (bottom) relay in the closed position removes the needed ground from the blower motor completely, while in another, direct ground is applied to the fused (30A) source through the primary relay. quietleaf's last post however, appears to be exactly what is necessary to protect the blower switch in high from over current, but still relies on the thermal limiter for the low and medium positions, as originally designed. Exactly how much protection the switch really has with so little resistance can only be determined by actually measuring the current when the the blower is in operation at these two remaining levels.

Ignore the top relay in both layouts, just pretent its not there and pass power directly to the blower motor.
-in my layout......
-power is applied to the coil of relay 2 and the postions of the contacts are switched.
-as you move the blower speed switch through the low, m2, & m1 positions, the blower motor gets its ground through the resistor bank.
-when you flip to "HI" however, the relay "de-energizes" and obtains its own ground as shown bypassing the blower switch.
-my design never uses the oem ground for "HI"

In quietleaf's layout, ignore the top relay and follow the same steps.
-his second relay stays "de-energized" during low, m1 & m2 but energizes during "HI"
-when "hi" is selected, power passes through the blower switch then comes around and energizes the coil
-the second relay contacts now are moved and the "HI" selection is now an open from pin 1 to pin 2.
~his uses the oem "HI" ground momentarily only as the alternate path is taken thus bypassing it.

a few thouths on my layout
- simpler to wire
-less retrofit wire required,
- you would have "HI" only if the relay coil were to fail and would be consistent with oem troubleshooting symptoms.
-my relay is energized during low, m1 & m2 and could increase current demand more often since its "on" three times longer.

a few toughts on his layout
-relay is de-energized duirng low, m1 & m2
-requires more retrofit wire
-tad bit more complicated to wire
-you would have low, m1 & m2 only if the relay coil were to fail
-you would use less power as the second relay is on only during the "HI" event.

Protecting your blower motor switch (non-EATC)

Reply #29 – August 13, 2012, 09:07:23 PM

I must be missing something :( I still don't see how switching to Hi de-energizes the coil in your design. Circuit 261 will always draw some current.