lylefikse Report post Posted March 8, 2012 I couldn't switch my engine heater to the floor setting (2007 Damon Tuscany). It is stuck on the defrost setting. No air going to the floor. Does anyone know if this switch is fused? Or is my switch in the dash bad? Can't find it in my owners manual. Share this post Link to post Share on other sites
dickandlois Report post Posted March 9, 2012 Think that your heater functions are controlled by solenoids. that being the case,I would look for the chassis fuse box(s) under the dash,drivers side. fuse size would be around 25 amps and located in the main fuse block. Now, as I ponder the question,do you get air flow from the defroster? When you switch the controls to redirect flow to the floor, does the air flow to the defroster stop? I found the floor ducts on my coach(a different brand) had never been connected to the floor registers. Most likely the heater controls are supplied by the Chassis manufacture not the Coach manufacturer. R.M. Share this post Link to post Share on other sites
KeithandBarb Report post Posted March 9, 2012 I had a similar problem with my 2002 Damon Escaper. The problem was not electrical but the mechanical vacumn lever that switches the vent flaps near the floor. The manfacture or installation caused the lever to be too far back and off centre so it could not be moved by the vacumn slide. After I glued a washer on the frame member to keep the lever slightly forward, the vacumn slide could then move the lever and heat came on to the floor. My description may sound a little cryptic but it should be obvious when you look at the heater control equipment on the floor. Hope this helps. However there still is not a lot of heat to keep the coach warm on cold snowy drives. KH Share this post Link to post Share on other sites
wolfe10 Report post Posted March 9, 2012 Yes, most of the dash HVAC systems are vacuum controlled. Start with the vacuum pump and work toward the dash HVAC control tracing the vacuum lines. Defrost is the default position in the absence of vacuum. Brett Share this post Link to post Share on other sites
dickandlois Report post Posted March 9, 2012 Brett, A question, I'm familiar with vacuum controls on the Gas units,but My Diesel Pusher uses electric motors / servo's to redirect air flow and a cable to control the mix of hot and cold air to set temperature. Do some of the Diesel units have a vacuum pump also? I did make the assumption that the coach listed was a Diesel powered unit !!! R.M. Share this post Link to post Share on other sites
wolfe10 Report post Posted March 9, 2012 Yes, many diesels have a separate electric vacuum pump to "power" the dash HVAC. Share this post Link to post Share on other sites
dickandlois Report post Posted March 9, 2012 Thank you, always learning. R.M. Share this post Link to post Share on other sites
hermanmullins Report post Posted March 9, 2012 Both of you have great Ideas, but no matter which he has, ITS Still Under the Dash. :( :( LOL Share this post Link to post Share on other sites
lylefikse Report post Posted March 9, 2012 Thanks. It is a diesel. I was looking for a fuse in the outside fuse compartment. I'll look under the dash. I was cold driving it through Nebraska two days ago. All the air was on the defrost and nothing on my feet, I stopped at rest stops twice to fire up the coach furnace to warm up. Coach got down to 45 degrees inside. Now I am home now and have time to work on it to track it down. I'll post when I find the problem. Sounds like I should start looking under the dash. Share this post Link to post Share on other sites
wolfe10 Report post Posted March 9, 2012 I would not start under the dash. Start by locating the small 12 VDC vacuum unit/air compressor. Likely in one of the forward-most basement compartments (forward of the front tires) or in the generator area if that is in front. Share this post Link to post Share on other sites
lylefikse Report post Posted March 10, 2012 Your right. Still looking for the vacuum pump. To dark now to continue. No fuse box under the dash. The system is vacuum, as there are vacuum lines under dash. Appears there is no power to the pump (wherever it is). Fuse for vacuum pump (In outside fuse box) looks OK. Need to test it tomorrow. I can manually push the lever and change airflow. Share this post Link to post Share on other sites
lylefikse Report post Posted March 10, 2012 OK, after your last reply, Brett, I couldn’t wait. I went outside with a flashlight and located the pump. It was up front in the compartment with the generator. The electric connection to the pump had come loose. I plugged it back in and everything works great. At least I don't have to test the fuse. Thanks again! Share this post Link to post Share on other sites
wolfe10 Report post Posted March 10, 2012 You are welcome. Glad it was so simple. Brett Share this post Link to post Share on other sites
lylefikse Report post Posted July 28, 2012 Brett, please help! Still having problems. Very hot this time of year without AC working right. Vacuum pump works only part of the time. Runs in spurts. If I unplug the vacuum loop for the internal pressure on the pump, the vacuum pump runs all the time. As soon as I put it back on the pump, it stops or runs in slow spurts.. I tried to plug the hose with a golf tee to get vacuum to the system ( pump runs this way) but still no luck with controls changing to floor or dash. Sometimes it will change to the dash for and hour or so and then returns to defrost default setting. I think it must be the switch on the dash. What do you think? Don't hear any vacuum leaks. Maybe a hose is kinked but don't see one. Share this post Link to post Share on other sites
wolfe10 Report post Posted July 28, 2012 You need to diagnose the issue with your vacuum system. Could be the vacuum switch or the pump or even a breaker supplying it. I would start by hooking up a voltmeter to the line to the vacuum pump and verifying whether you are loosing 12 VDC when the vacuum pump stops working. Brett Share this post Link to post Share on other sites
chucknewman Report post Posted July 28, 2012 Brett's suggestion is the easiest way to start troubleshooting this. If you have good battery voltage at the pump, whether running or not, since the pump "runs in spurts" that would indicate the pump is over temp cycling or, more likely, you have a small leak in a vacuum hose. Or both. That is because most of the small vacuum pumps are not designed to run continuously or very often. A leak will cause the pump to run more than normally required and may overheat the pump motor resulting in internal thermal cut out. Until it cools then the cycle begins again. The rate this happens depends on the volume of your vacuum tank (if you have one), and the size of the potential leak. If you don't have voltage issues, I would get a new piece of hose about a foot long at the local automotive store. Securely clamp one end or preferably put some silicone sealant in and around one end and let set for 48 hours. Then attach the open end of the new hose securely to the vacuum pump. If it does not run in spurts that indicates you have a leak somewhere in the hose system -- not uncommon. I would also get a vacuum gauge and plumb it into the line using a plastic ribbed tee adapter to see what is going on. You should have 10 to 30 inches of vacuum for the control valves to work. Brett may know a good number to advise. If the pump still runs in spurts with the new hose piece, I would replace the pump. Share this post Link to post Share on other sites
lylefikse Report post Posted July 29, 2012 After nearly giving up, I discovered the hose from the pump to the vaccum tank was plugged. I blew it out with compressed air and reconnected it to the pump and tank. Everything seems to be working now. Don't understand how this got plugged. Thanks for the help. Share this post Link to post Share on other sites
jrwitt Report post Posted July 29, 2012 Pixie dust! Those little critters can get into anything. lol Share this post Link to post Share on other sites
lylefikse Report post Posted August 7, 2012 Pixie dust is right! We took it out this weekend and had problems again. When we got home I took this vacuum hose out of the wire harness and installed a new hose. I zip tied it to the outside of the wire harness. Everything works great now. Pump runs like it should, instead of in spurts. The old hose must have been pinched in the harness causing a weak spot that would pinch off the line sometimes. Big headache to figure out, but cheap and simple fix. Share this post Link to post Share on other sites
