We have a 2003/4 international t444e. We have only had this thing for about a month and 3500 miles into our first trip with 1400ish miles to go westward on the i40 back to phoenix. This bus has the step heater, driver, and rear heater. Previous owner removed rear or midship heater and made a loop. That loop puts off a crazy amount of heat. I saw another thread where someone mentioned they were designed to be shut off in summer. The previous owner mentioned that there are shut offs under the hood but that it would mess with the cooling. I have seen those valves. It really as easy ass turning the valves off so I dont roast for the next two days or do I need to plumb in a proper bypass before the heater cores. We live in phx so being able to bypess them 99% of the time would be awesome. However Id like to have the option to use them in the future.
Turn off the valves...that's what they're there for and it won't cause you an issue. Because the heater control valve can leak, it's common for buses and semis to have those valves to cut off flow through the heater core during the summer. We're also in AZ...so I know of what you speak!
I run all sdummer long with my valves closed.. I have electric valves on my DEV bus that are closed unless my heating systems are actually in use.. if i didnt close those valves, my Air conditioners wouldnt stand a chance
One more vote for closing the valves. I used to drive school busses, and most of them had the manual shut off valves, whether Tomas, IC or Bluebird. We shut them in the summer, and then wondered why we weren't getting heat in the winter when we forgot to reopen them I believe the heaters are on a completely separate circuit from the engine cooling system.
You are all geniuses! First time on the entire trip drove with windows closed and mini split cranking away after anout noon today. Catfish round-up rv park (not kidding) to loves trucl stop in gallop without a single issue. 733 miles. Seriously check out catfish round up though. Haha it was a great meal and little rv park