fan blows ac fuse... elec. help needed
Thread Starter
Racer
Joined: Oct 2011
Posts: 417
Likes: 2
From: Blacksburg Virginia
fan blows ac fuse... elec. help needed
My fan would not blow on anything but high speed....so I replaced my AC fan relay and resistor.
as soon as I turned it on, it blew the AC fuse (25amp).
I assume something is shorted, but where do I start, and how do I check....electrical was never my strong suit.
as soon as I turned it on, it blew the AC fuse (25amp).
I assume something is shorted, but where do I start, and how do I check....electrical was never my strong suit.
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
Are you sure that you got the right relay..
With the control set on any other setting than high you use the resistors to give you the different speeds through normally closed contacts of the relay.. I would try putting in the old relay with the new resistors..the relay is only operated when you select the high setting..
With the control set on any other setting than high you use the resistors to give you the different speeds through normally closed contacts of the relay.. I would try putting in the old relay with the new resistors..the relay is only operated when you select the high setting..
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
If your blowing a fuse, then there is a path to ground in the power circuit.. best way to trouble shoot this would be to Connect a meter to the (C878) side of the fuse [I would disconnect the battery] the meter will indicate a short <1 ohm. Now disconnect one component at a time until the meter indicates an "Open" or Mega ohms.. now you have the problem narrowed down to a section/Component
Thread Starter
Racer
Joined: Oct 2011
Posts: 417
Likes: 2
From: Blacksburg Virginia
I checked the fan, its fine. When I check the voltage coming off of the resistor it is the same regardless of the setting on the fan dial. Doesn't that mean that the resistance is always the same? Therefore, I think the problem is actually in the manual control panel.
any more ideas?
any more ideas?
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
The purpose of the resister is to Limit the amount of Current (power) is flowing into the Blower motor.. The multi position switch dirrects the power to the resister's. High speed is accomplished by energizing a coil in a Relay (#52) and re dirrecting power from (S257) Assuming of course the Schematic I'm looking at is correct!
Your problem is blowing a fuse, so there is a high current load somewhere between the fuse and (C137) ?
I suppose this could also be a blower motor drawing high current?
Your problem is blowing a fuse, so there is a high current load somewhere between the fuse and (C137) ?
I suppose this could also be a blower motor drawing high current?
Last edited by desertmike1; May 18, 2013 at 07:26 PM.
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
In your original post you stated that the fan would run in high speed. You changed the relay and resistors and blew the fuse.. Something you did created the short, or the relay is not the right one..
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Thread Starter
Racer
Joined: Oct 2011
Posts: 417
Likes: 2
From: Blacksburg Virginia
When I put it on high, c 52 is energized and changes the circuit from 101 to 2.... Correct?
Then when not on high the power to the fan flows through 101.
Should 101 be two or three different voltages based on the fan speed? What are those voltages? If I see no change when the selector is changed in the 101 voltage...then the resistors or the switch must be bad. Right?
Then when not on high the power to the fan flows through 101.
Should 101 be two or three different voltages based on the fan speed? What are those voltages? If I see no change when the selector is changed in the 101 voltage...then the resistors or the switch must be bad. Right?
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
In your original post you stated you blew the AC fuse, now you have moved past that to the rest of the circuit?? If you get voltage as far as 101 then unless the relay n/c contacts are not making contact the blower should work on the lower speed settings.. 