fan relay

[mark b]

looking for electrical debug suggestions - the low speed fan relay will blow after the fan runs for a minute or 2. I am going to inspect the wiring but wondered will a malfunction coolant temp sensor do this? Bad wiring grounding out? I would have thought if the fan was drawing too much power it would blow the fuse and not the relay.

thanks in advance for any suggestions.

 

[norbs]

There is no fuse for the fan relay, only a fusible link, it takes almost a dead short for it to melt. maybe the bearings are seizing in the fan motor?

 

[Ormand]

The low speed relay is triggered (or should be) by the ECM, or by the A/C pressure switch. There is a fuse (the gauge fuse) on the control side of the relay- the low current side. Fusible link protects the "power" side. Could be a problem with the fan motor, or maybe a short in the wiring between the relay and the motor. Also, might want to make sure the connections are in good condition at the motor. When the relay "blows", what does it do? Melt internally?

 

[norbs]

Thats a good question, i have never seen a relay melt down, but i have seen the weather pack plug melt on the fan connector. The control fuse would not probabaly blow instantly if it was shorted.

 

[mark b]

good info, turns out the relay will usually reset when it cools down. I tried a circuit breaker type tester bypassing the relay - it did the same thing. The fan is drawing too much power.