Well boy did I just have fun tracing down a fuse blowing/wiring problem on CAV #15. Anyway I will try to boil this down as best I can, but suffice it to say that all CAV owners should be on the lookout for relay issues.
Where it began. Over the winter I upgraded fans to 1" larger SPAL fans that flow about twice the flow of the stock fans. Mainly because the car temp would creep up on the grid during very hot days (95 deg. +). I also moved the condenser to the front of the radiator and would need some additional help. When I first started the car after the upgrade I noticed a 15A fuse blew right away resulting in the fans stopping. In the "quick fix" way of correcting this problem I went up to a 25A fuse and all seemed fine.
About a week ago I noticed the Lucas fan switch acted backwards one day and then the next mechanically broke inside. I ordered a new switch and went to replace it. I found that the switch failed due to over current! Now by looking at the wire colors and going over the fuse increase in my head I was convinced that they did not use a relay for the fans and were using undersized wiring. I bought new relays and 12/14 gauge wire.
In my detailed tracing of the fan circuit from one end of the car to the other (including thermal switch) I eventually found that THEORETICALLY they are using a relay to turn on the fans! It is mounted in the front near the horns. It THEORETICALLY draws main power through another 30A fuse and the Lucas switch and thermal switch were used to turn on the relay. After lengthy and methodical check out the switch side of the circuit was drawing ~23A! Well that is a little overkill to turn on a relay I thought. Come to find out the relay was wired wrong. The fat wires running through the 30A fuse was being used to turn on the relay and the small wires, switch, and thermal switch was supplying the actual required current flow to the relay/fans. Very nice! Anyway after rewiring the relay and reinstalling all of the other wiring that I had disconnected for diagnostics the fans work fine with the 15A fuse. Here are a few summary points that owners should look at and consider:
1.) If when you turn on the main disconnect to the car with the key out of the ignition and you here a "click" of a relay turning on this is a sign of a problem. I always wondered why a relay was being turned on like this and now I know.
2.) If you do here a click or notice that the fan switch is drawing too much current then check the wiring on the relay.
3.) All of these 30A relays that look exactly alike are NOT!!!!!! We looked at the pins on the Bosch units which the car uses and they are definitely different the two other like configured name brands. So if you do replace a Bosch relay you better double check the pin configuration.
4.) I did notice that one of the relays near the fuse box was not a Bosch (only one in the car) and was pin configured like the other name brands. Hope this is supposed to be in the car. It is difficult to check the configuration of the wiring in the car to see if this relay is wired correctly.
Hope this long winded post helps.
Where it began. Over the winter I upgraded fans to 1" larger SPAL fans that flow about twice the flow of the stock fans. Mainly because the car temp would creep up on the grid during very hot days (95 deg. +). I also moved the condenser to the front of the radiator and would need some additional help. When I first started the car after the upgrade I noticed a 15A fuse blew right away resulting in the fans stopping. In the "quick fix" way of correcting this problem I went up to a 25A fuse and all seemed fine.
About a week ago I noticed the Lucas fan switch acted backwards one day and then the next mechanically broke inside. I ordered a new switch and went to replace it. I found that the switch failed due to over current! Now by looking at the wire colors and going over the fuse increase in my head I was convinced that they did not use a relay for the fans and were using undersized wiring. I bought new relays and 12/14 gauge wire.
In my detailed tracing of the fan circuit from one end of the car to the other (including thermal switch) I eventually found that THEORETICALLY they are using a relay to turn on the fans! It is mounted in the front near the horns. It THEORETICALLY draws main power through another 30A fuse and the Lucas switch and thermal switch were used to turn on the relay. After lengthy and methodical check out the switch side of the circuit was drawing ~23A! Well that is a little overkill to turn on a relay I thought. Come to find out the relay was wired wrong. The fat wires running through the 30A fuse was being used to turn on the relay and the small wires, switch, and thermal switch was supplying the actual required current flow to the relay/fans. Very nice! Anyway after rewiring the relay and reinstalling all of the other wiring that I had disconnected for diagnostics the fans work fine with the 15A fuse. Here are a few summary points that owners should look at and consider:
1.) If when you turn on the main disconnect to the car with the key out of the ignition and you here a "click" of a relay turning on this is a sign of a problem. I always wondered why a relay was being turned on like this and now I know.
2.) If you do here a click or notice that the fan switch is drawing too much current then check the wiring on the relay.
3.) All of these 30A relays that look exactly alike are NOT!!!!!! We looked at the pins on the Bosch units which the car uses and they are definitely different the two other like configured name brands. So if you do replace a Bosch relay you better double check the pin configuration.
4.) I did notice that one of the relays near the fuse box was not a Bosch (only one in the car) and was pin configured like the other name brands. Hope this is supposed to be in the car. It is difficult to check the configuration of the wiring in the car to see if this relay is wired correctly.
Hope this long winded post helps.
