olritter Report post Posted July 24, 2020 My overheat alarm goes off when we climb in elevation even tho it is not overheating. It is a 3-wire alarm. Has anyone had this problem and is there a fix? Share this post Link to post Share on other sites
rayin Report post Posted July 24, 2020 Have you cleaned out the radiator fins? This can cause overheating. How did you determine the alarm is sounding although it is not really overheating? The sales brochure tells me little concerning your issue. Share this post Link to post Share on other sites
rossboyer Report post Posted July 24, 2020 Please search for a detailed post “Procedure For Cleaning Rear Mounted Radiator” where I detailed the procedure that FREIGHTLINER told me to use. Possibly, it will help you. Share this post Link to post Share on other sites
kaypsmith Report post Posted July 24, 2020 The CAC is as much important as the radiator. How hot does your gauges show when the alarm goes off? The heat sending unit to the alarm may be faulty, just a thought for things to look for, if there is a separate sensor. Share this post Link to post Share on other sites
manholt Report post Posted July 25, 2020 Yellow or red light? If it's yellow, drop down a gear & keep your RPM up, it will help with the heat build up....also, as suggested clean your radiator and CAC, it's important. As Kay said, could be a bad coolant sensor...normally on outside of your overflow tank by radiator and looks like a spark plug with a two wire clip connector. Un clip and see if sensor goes off on next hill, then reclip. About $35. Share this post Link to post Share on other sites
euphoria2me Report post Posted August 3, 2020 I have a similar problem with my 2005 Monaco Diplomat with a 400 ISL Cummins and 62000 miles. Had the radiator and CAC removed and cleaned in Denver, changed the filter, checked for exhaust leaks and she still overheats going up-hill, not on flat terrain. I'm running out of options. Any suggestions? Share this post Link to post Share on other sites
jleamont Report post Posted August 3, 2020 15 minutes ago, Euphoria2me said: I have a similar problem with my 2005 Monaco Diplomat with a 400 ISL Cummins and 62000 miles. Had the radiator and CAC removed and cleaned in Denver, changed the filter, checked for exhaust leaks and she still overheats going up-hill, not on flat terrain. I'm running out of options. Any suggestions? I responded to the post you created. Share this post Link to post Share on other sites
