problem with relay?

[62 Bowtie]

any ideas as to why i keep blowin fuses is it becuz of fuse rateing? all wires are good no hot touching grnd. Heres what we got 8ga from batt to 87 terminal 0n 30amp relay 10ga from ign sw to pressure sw on tank 10ga from compressor to 30 on relay 8ga from other side of pressure sw to grnd on relay 10ga from neg on compressor to frame 10ga from relay to frame grnd hope this is clear also useing 25amp fuses one at the battery and one from ign wire thanks dudes

[dwcsr]

Originally Posted by 62 Bowtie

any ideas as to why i keep blowin fuses is it becuz of fuse rateing? all wires are good no hot touching grnd. Heres what we got 8ga from batt to 87 terminal 0n 30amp relay 10ga from ign sw to pressure sw on tank 10ga from compressor to 30 on relay 8ga from other side of pressure sw to grnd on relay 10ga from neg on compressor to frame 10ga from relay to frame grnd hope this is clear also useing 25amp fuses one at the battery and one from ign wire thanks dudes

It sounds like you have 2 fuses on the same wire?. That doesn't work . What kind of compressor, make, model? Where is the power source located in relation to the compressor and relay? It sounds like you have your relay wired wrong.

Not sure why you have a 10ga on the rely trigger and ground but its way to big.

Ignition to Relay terminal 86 should be 16 ga with a 3 to 7 amp fuse. Relay terminal 85 to ground or through the pressure switch to ground should be 16 ga. 14 ga if the battery is at the other end or the vehicle from the relay. This circuit doesn't draw very much so 10 ga is way overboard.

12 ga from battery to Terminal 87, 10 ga if the battery is more than 10 ft away from the relay. The fuse or circuit breaker should be 50% - 75% above the running draw of the compressor and should be the "slow blow" type. Relay Terminal 30 going to the compressor should be 12 ga again depending on where it is maybe 10 ga. and the ground from the compressor can be 12 ga because its going to be very short. Do not use the same ground point for the relay and compressor.

Running monster wire doesn't get you anything more than a little less beer money and in some cases actually makes it worse. Big cables store energy and can make fuses blow when the device shut down.

Ideally the relay should be very close to the compressor so you can use the 12 ga wire without worry. The battery should also be close but if not run a #10 wire back to it with the fuse near the battery or power source. The trigger wires can be long and still 16 because the draw is small and again fuse near the power source.

[62 Bowtie]

thanks for the reply ok yeah the relay and compressor are same grnd 1 fuse inline from ign sw to pos on press sw and 1 fuse inline from batt to 87 on relay. the compressor is an older big red model unknown theres no number on it 1 compressor 1 30amp relay 1 7gal tank relay is close to compressor all are behind cab in the bed of the truck

[dwcsr]

Big Red compressors had a 30 amp draw when they were new. So you may be 35 or 40 if its old. That makes you low on the relay and low on the fuse. Go with a auto reset 40 or 50 amp circuit breaker and a 50 or 60 amp relay. Then separate the grounds, they can be right next to each other but not on top of each other on the same screw.

[6doggie3]

Thanks for doing leg work Bowtie! where would the circuit breaker go and would a ford type starter relay work? Im having a hard time finding a 50 amp relay! And if u have a diagram of some kind would be very helpfull THANK'S

[dwcsr]

The circuit breaker goes as close to the battery as possible but no further than 18 inches away. You should be able to get a relay at any parts store. Ford starter relays are not design to operate like that, they are intermittent relays made to be engaged for 30 second to a minute and no more. The coil in them also draws much more amps.
http://www.aeicomp.com/Detail.asp?Pr...03.113_BU5084W