ISBXT 350 Hi Coolant Temp Alarm

[pboserup]

Driving back from Chicago in pleasant 70 degree weather the hi coolant temp alarm came on several times. Had no problems when we left Florida with temps in the 90's. The check engine light never came on.

Easing up on the throttle to 55 mph would allow the temp to come back down out of the red zone on the gauge and after 1 - 2 minutes the temp would return to normal. Coolant level is is good and no sign of any leaks.

When I first got the unit ('09 Fleetwood Discovery) in late August, my son and I both noticed that the cooling fan produced a tremendous wind when backing up to the garage where it would blow papers off of a table in the garage. There is no longer and apparent airflow through the radiator at idle, even during a stop to check the fan during a hi temp episode.

Does this unit have an electric clutch? Could it possibly be designed so that when it fails it is disengaged?

Any thoughts on what might be wrong?

[Spikester]

I believe you have a mechanical fan clutch, by 08 does. With no air being blown through the radiator during a high temperature episode I would suspect a bad fan, fan clutch, or blockage of the radiator. I would suspect that when the fan clutch engages you should be able to hear the increased noise level coming from the rear of the coach.
My temperature fluctuates from 190 to 210 degrees in warm weather as the fan engages and dis-engages. The cool down from 210 to 190 is rapid, taking maybe 10 secs or so. Fan clutch rarely engages when outside temps are below 65 degrees, only when pulling long grades.

Spike

[pboserup]

I had a look on Sunday and there is no blockage and
the fan clutch in this 2009 model is electrically controlled.

I disconnected the electric connection, ran the engine and observed that the fan was engaged and the airflow through the radiator was as expected.

I turned off the engine and connected the clutch and started the engine, again no air flow.

I just had a thought, I wonder what affect if any, turning on the dash A/C would have on the fan operation. I'm pretty sure that during each overheat alarm we were running on the roof air. I'll check this evening.

[GaryKD]

Hi pboserup,
I'm going out on a limb here as this is not my main skill. Disconnecting the electric clutch may have put the fan in "default" run all the time mode. When the electric connection was again made it is not clear, to me, the temp was up enough for the fan clutch to be engaged. I'm not sure how you would diagnose the circuit and components that control the clutch.

[pboserup]

Brought the unit in for service and it turns out that electric fan clutch was bad. To my good fortune it was a warranty replacement and did not cost a dime.
pb