In the summer of 2005 we decided to head north and get out of the Texas heat. We have a 1970 Glastron motorhome that we have traveled in for 16 years now. It has always had an over heating problem so summer travel has been challenging. To prepare for the trip I put in a new over sized radiator and an electric cooling fan. I had the fan wired to a switch on the dash and only had to use it when we were in stop and go traffic. The first day out everything was going just fine until the sun got low enough in the sky to make sitting behind the windshield feel like being in an oven. The air conditioner just could not keep up in 104 degree heat. I pulled in to a KOA in the Texas pan handle and my wife went into the office to secure us a campsite for the night. I stayed behind the wheel to monitor the engine temperature and make sure our new cooling fan was doing its job. She was only gone for 5 minutes when the engine just stopped running. I started trying to figure out the problem but the heat got to be to much. The owner of the KOA said he could tow me to our space where we could plug in and get the roof air conditioner going and then sort the problem out. There were other people checking in so we waited for what seemed like an eternity. Finally here comes the owner with his John Deere tractor. After hooking a chain to our bumper he pulled us in low gear (like slow motion) on a road that must have gone by every space in the entire campground. When we finally arrived at our space there were people walking alongside wanting to here what happened. One guy was a Dodge mechanic and helped me find the problem. I learned that day that a 30 amp cooling fan hooked up through the ignition switch will melt that switch like cheese on a enchilada. 

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Yo Gary, been there done that n got the T Shirt as they say. This past June we drove through the panhandle and New Mexico and Arizona and when we pulled into the campgrounds we plugged up the RV, turned the AC on high, n just stayed inside till almost dark.

Yeppers on the ignition switch, it was designed to handle maybe 10 amps max, so 20 to 30 through it will overheat n cause all sorts of nasty undesirable consequences. By now I guess you have fed the fan switch circuit via a higher ampacity source???? but if you just have a need to use the ignition switch such that the circuit isnt energized when the ignition is OFF, all it takes is a simple 12 Volt 30 amp DC relay set up so an ON contact off the IGN switch only supples an amp or less to the coil (activation) side of the relay, while its other power contact side serves the switch and actual fan. Id suggest a 30 amp fuze or circuit breaker right at the 12 volt power (Fan side of relay) source to protect the wiring, and if the fan actually draws near 30 amps (that sounds high) I would use 10 gauge wire to the fan.

I used to buy used Class C Ford powered RV's that came from the factory with 3 core radiators which I always removed and replaced with higher capacity 4 core units, new radiator and heater hoses and thermostats, fan clutches and water pumps if needed, and used wetting agents, super cool and anti rust and other assorted snake oils, BUT THEN I COULD CLIMB MOUNTAINS AT 100 DEGREES AND HORSE LAUGH THE DUDES WITH $200,000 RV's THAT WERE OVERHEATING which the first wife said was being MEAN lol

Radiators, belts, hoses, tires are things I insist on being near perfect and oversized where possible when I hit the open road, especially when driving in lonely deserted remote areas in the arid Southwest

Yall take care now

Ol John T in Indiana
Hey John. I did use 10 gauge wire and instead of a relay I went straight to the battery because in my situation the battery is close to the fan. The fan I got called for the 30 amp fuse and it works fine. I do still have an over heating problem though. I have even installed a spray bar in front of the radiator hooked up to the 40 gallon fresh water tank so I can occasionally turn a valve from the drivers seat and shoot water on the radiator! If ambient temps are in the high 80's and below I can climb hills and all no problem, in the mid 90's it gets precarious.

This is a common problem with 318 powered (under powered) motorhomes like mine but I think I may have other issues. The engine needs a rebuild now and I will be sure to check all cooling passages well when it is apart.

My travel opportunities are mostly in the summer so I avoid the Southwest and head to the Northwest. I overheat just about as easy as the motorhome does anyway so it works out. I'll save the Southwest for the retirement years when I can go in the winter.

Snow birds head south for the winter so am I a sunbird because i go North for the summer?

Thanks, Gary
Good old Texas heat!  Helen




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