The radiator cooling fan on all Renaissance® coaches prior to unit 62032 is designed to operate in three stages. When the engine is first started, the fan clutch is in the "Brake" mode, which prevents the fan blades from turning. After the engine reaches operating temperature, the clutch shifts to "Slip" mode. In this stage, the fan blades turn, but at a slower speed than the engine. If the engine begins to run hotter than normal operating temperature, the clutch will shift into the third stage, or "Direct" mode. In this stage the fan clutch "locks" the hub and pulley together, causing the fan to operate faster (roughly the same speed as the engine). Listed below are the temperatures that shift the clutch to each stage:
|Engine Temp Rising||||196°F (90°C)||205°F (96°C)|
|Engine Temp Dropping||175°F (80°C)||190°F (88°C)|||
The clutch system is designed to operate in Slip mode about 85% of the time the coach is driven. This results in optimal fuel economy, and minimal fan noise while the engine is operating. The temperature gauge on the dash will also display this variation in temperature. It is normal for the temperature gauge to continuously fluctuate between 180°F to 205°F.
Attached to the back of the clutch are two air lines. These supply air pressure to ports on the clutch to control the Brake mode and Direct mode. Air pressure should never be applied to both ports at the same time. See Figure 1.
If you experience engine overheat problems and the clutch doesn't shift into Direct mode, the fan can be locked in the Direct mode to enable the coach to be driven to a service facility. This is accomplished by bolting the clutch pulley to the hub. Below is the procedure for doing this.
If you need further assistance, contact the MCI Customer Support Center at (800) 241-2947.
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