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Re: Low speed relay/resistor - ? For Ari Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Sun, 8 Mar 2009 15:59:25
In Reply to: Re: Low speed relay/resistor - ? For Ari, gman, Sun, 8 Mar 2009 12:40:56 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Which 30 amp fuse is blowing? There are two in the fusebox. The Low Speed fuse is #7 - second from the left, on the row farthest from the relays. The High Speed fuse is #8 - second from the left, on the row closest to the relays.
Low speed circuit - 12 volts comes through Fuse 7, through the Low Speed relay, to the series resistor, to the fan.
High speed circuit - 12 volts comes through Fuse 8, through the High Speed fan realy, to the fan.
Each relay is triggered by the thermoswitch mounted in the bottom of the radiator. It has three wires, the black wire being ground, Blue is the Low Speed relay, Blue/White drives the high speed relay.
What usually happens is the resistor dies. So you get 12 volts at the side of the resistor away from the fan (relay side), but the fan doesn't start. Then the High Speed relay closes, and the high current causes the fuse to blow.
Which switch are you looking at when you see "no current from the switch to the resistor"?
Possible issues:
Blown fan resistor
Bad fan (pulls too much power)
Bad fan (pulled too much power, now dead)
Burned relay contacts
Which fuse was blowing?
Have you measure the resistance of the resistor?
Assuming it is a stock radiator fan thermoswitch, the low speed should kick on when the coolant temperature at that part of the radiator hits 90C. The high speed kicks in at 106C. Note - this isn't the temperature on the gauge in the dashboard. If the thermostat is sticking (controls coolant flow) the engine can overheat an the fan never come on. Why? The thermostat controls flow to the radiator. If it stays closed, the radiator never gets warm, and the thermoswtich in the radiator (at the cool end of the radiator, no less) never kicks on. However, blowing fuses is usually a sign of a fan trying to turn on.
posted by 192.249....
, Sun, 8 Mar 2009 11:01:21, Sun, 8 Mar 2009 15:59:25 <-- Viewing This Message, Sun, 8 Mar 2009 19:34:25
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