[Dan]

What is the VIN number of the vehicle? You show a Series 60 engine but what transmission do you have iiiin this conversion: ATEC HT755crd or World Transmission?

[Mike]

Vin is R1001788. Tranny is Ht755cr.

[Dan]

When the Detroit series 60 engine was introduced we did not have the World Transmission yet. Plus the DDEC level at the time was DDEC II. The electronics did not support fan clutch control. So we used a temperature sensor mounted in the radiator cross pipe above the engine to control the fan. When the coach was started we supplied 24 volts to the switch and when it reached first speed temperature wire #291 out of the switch became hot and 24 volts was supplied to the fan cluthc to get first or low speed. When the temperature reached the setting for high speed fan then power was supplied through the switch to wire #292 and we get high speed or lock-up on the fan clitch. Look at the diagram below. I highlighted the system in yellow.

To manually get the fan to work you would need to supply 24 volts to wire 291` for low speed or wire 292 for high speed. Go to connector C427 at the temperature switch and jumper pin 3 to pin 1 in the harness connector to have full speed.

As soon as Detroit came out with DDEC III, we began using the two relays, R78 and R79 on the XLs for fan control.

For the above work-around remember to check and verify 24 volts at pin 3 in the connector at the temperature switch. If no power check CB30 or CB130.

[Dan]

Thank you PrevostService. I will print your post and keep it handy in the bus.

[Bernard]

Thanks Prevost Service (whom you will all meet at our seminar next month). Anyone with the early series 60 coaches with the 5 speed transmission should copy this because it may be very helpful

[Robert]

Just for FYI I have a 1994 40 ft RV shell with the Series 60 and the World transmission with DDEC 111. It has the coolant temperature switch in the radiator crossover pipe and no relays to control the fan clutch.