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Fan Clutch breaker
Getting ready to replace the fan clutch I noticed I am missing 4 of the reset able circuit breakers Cb 130 and 131 Are for the fan clutch Ours is presently locked down. Looks like some on got creative with the wiring. Is Prevost the only supplier for these? I think they are ETA 127-T12 H.
Thanks
Craig
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12 Replies
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Relays #s 78 & 79 in the engine compartment electrical box above the engine control the engine driven fan clutch?
Your results my vary?
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Craig, You say the CB’s for the clutch are missing, but you say the clutch is locked.
What do you mean? The clutch can be locked using the tabs and provided bolts (not a good long term method) or electrically using the relays lonestar mentions. If locked electrically you are getting power? Or not?
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Position 9 from left looks like RH stop & cyclop lts, Position 11 from left should be power for fan clutch, And is the wire on the bottom moved to far right? Missing relays R9 Back up lights- R36 AC std clutch- R81 water heater Wabasto Relay R78 low speed fan R79 High speed but if the #11 Breaker is disconnected at bottom neither 1 will work. find an old relay and jump it fo testing.
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I think yours is the same as my 1994 series 60 XL. There are no relays for the fan clutch. It has a thermo switch in the metal upper rad hose that controls the fan high and low speed. My breaker has wire 427 attached to the upper conection on the breaker and goes on the thermo switch. If you check the wires on the breaker on the right hand side and find the one with wire 427 that would be the one( mine is a 6 amp). The fan might be locked because the thermo switch failed. I just replaced mine because the fan would not engage, with one that came with the bus in the spare parts bin, so I think it has failed before and the PO had a spare.
Herb
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I think your right I don’t see on Craigs R78 & R79 Here’s mine see R78 & R79
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Jon, The clutch is locked via the two tabs. Our coach is a DDEC II. Apparently previous owner had a issue of some kind . And some one disconnected wires and removed the circuit breakers. Hopefully I can find the wires and Try to figure out what the issue is. I have not unlocked the fan I am going to do that this morning. Will rotate and see if I have a bad bearing.
Thank You
Craig
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Herb I will try to find wire number 427 .
Thank You
Craig
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Here’s what I have in my notes covering the fan control for DDEC II
Prevost used the two speed fan clutches with the introduction of the Series 60 engines. The first Detroit engines used were DDEC II configuration and had no fan control avaiable in the software. To make it function a thermal switch was used. It was mounted in the radiator cross pipe over the engine. It would turn on low or high speed as the temperature reached around 190 degrees F for low and around 200 degrees F for high speed. See diagram. : This control method was with the power side of the fan clutch. In other words when the temperature reached low set point, power was fed through the switch and down wire 291 to give us low speed. As the temperature continued to rise, the same would happen for the high speed and power was fed through the switch to wire 292 for the high speed. The grounds for the fan clutch were constant to chassis ground.
With the introduction of DDEC3 the present style of fan control was supplied by Detroit Diesel through their ECM.
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My bus is 1994 Series 60 DDEC III and has the thermo switch style, not the DDEC controled relays from the factory .
Herb
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My 97 had the relays 78 and 79 but since I don’t have it the only way I would know which breakers were for the clutch would be to go to the wiring diagrams. On the road now and not going to take the time.
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A 94 with DDEC III?
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Tom here is a pic of my ECM.
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