For those of you who are experiencing frequent overheating with a 2007-2009 or similar year diesel pusher with a Cummins ISC 8.3l engine on a Freightliner XC chassis (mine is a 2008 Fleetwood Providence), here is my experience resolving the problem.
The cause of this issue was that the Cummins ECM only provided a Fan Clutch control signal, while the Horton clutch was not designed to send a speed signal back to the ECM. Therefore, the fan clutch would not always engage to bring the fan up to speed after highway driving and slowing down to 20 to 30 mph.
I found that most mechanics, including some Freightliner Oasis centers, were not aware of this issue, or even interested in servicing an RV over 10-15 years old. Subsequently, I had to do my own research to avoid thousands of dollars of extra costs.
It appears that Horton recognized this issue around 2012 and issued Product Technical Bulletin PTB1202. This bulletin states:
“If an overheat occurs, turn vehicle off, wait 5 min and restart. Be sure to verify the swage is not leaking. If clutch engages after the restart, install the following in-line device:
2007-2009 Engines: 995595
2010-2013 Engines: 994670”
Since I had a 2008, I went to the Horton website (www.hortonww.com) and learned that part #995595 is actually two items (Anti-Rotation Bracket 995580 and the Guard Dog Viscous Speed Controller 994671). The Anti-Rotation Bracket has a 6 pin connector (instead of 2 pin) and includes a set of replacement fan bolts that must be torqued to 106 in-lb. These bolts allow the bracket to sense fan speed. The Guard Dog connects between the 2 pin ECM connector and the pin of the bracket. After installation, I have not had an overheating issue again.
If you want to do this yourself, the parts cost around $650. If not, be careful who you have do the work and make sure they understand that they need to replace both the bracket and the Guard Dog controller.
