Technical Tips #32
By Bob Lowe
Motorhome Walk Around Hints:
AC Generator (Gas)
- Exercise it regularly by running it with 75% load (typically both Air conditioners turned to COLD temperature or two 1500 watt electric heaters)
- Monitor voltage and ensure that it is not varying by more than +/- 2 volts, if it is exercise more
- Service all generators annually according to Manufacturers maintenance schedule.
- Practice safe dumping technique using disposable gloves.
- Lubricate termination valves with SILICONE lubricant (not oil based). Empty tanks, spray valve rubbers on slide. Some owners drill a small 1/8" hole above valve handle; spray Silicone in hole and plug with small self-tapping screw.
- Install Tank Rinse Flush fittings on both Black and Gray water tanks and flush tank with each draining. It is helpful to make a water hose manifold with hoses to both tanks and a junction tee with an anti-siphon water fitting on it where water hose connects
- Use clear drain fittings to confirm tanks are clean after flushing
Water Heater (with DSI)
- Use di-electric grease (also known as tune-up grease) on all contacts
- Remove and reinstall white printed circuit board connector with this grease after gently using an ink eraser to clean any green corrosion from the circuit board contacts.
- Power flow is through thermostat (usually fixed and not adjustable) then through a thermal-fuse (covered in plastic sheathing) to a high limit switch. Power should be traced through this sequence before condemning circuit board. Ensure all grounds (circuit board, gas valve, and burner spark ignitor) are clean and corrosion free
- Most can be serviced from the exterior if a large metal cover is visible. Remove four screws (not those around air intake and exhaust) and slide off.
- Power flow is from Power Switch, Thermostat, Sail Switch, Relay, Limit Switch and then the Circuit Board. (See Tech tip 8 for details)
- Check all connections for security and corrosion. Boards do not fail as frequently as believed. Poor connections will cause poor or no furnace operation and can damage board.
- If thermostat calls for heat and furnace fan runs but does not produce heat then check continuity on limit switch. Most frequent style of limit switch is a button style bi-metallic switch. Dirt can enter the buttonhole and prevent the switch from closing. Sometime removal of the switch and cleaning corrects the problem, however replacement with a new style virtually eliminates the problem. Limit switches are usually mounted on the heat exchanger of the furnace or in the heat duct close to but often behind the furnace. Sometimes there is access from inside the coach, often the furnace must be removed to inspect. The wiring is visible from the outside access door area.
- Ensure all connections are clean and corrosion free. Use di-electric grease to protect. Disconnect both 12V and 120volt AC before working on fridge.
- Clean and regularly check burner area under chimney for rust and chips that drop from chimney. (See Tech Tip #29 and 7 for hints)
- Older Dometic electronic models require revised ground kit available from Dometic.
Recommendation: If you must operate your refrigerator while traveling, we suggest that you run your fridge on the AC generator or 12V if available, not propane for safety reasons. Utilize a small battery powered "FridgeMate fan" and reduce door opening while travelling will maintain suitable fridge and freezer temperatures for 6-8 hours.
- Lubricate the step every 30 days using Kwikee "Grease Gun in a Can" an aerosol based liquid grease. (see Tech Tip 1 & 14)
- Coat all rod bearings under step mounting are as well as pivot points that are visible.
- If step is not regularly lubricated then liberally spray the rod bearings with WD40 while moving step in and out until the rust is gone from the bearings then dry and apply the grease as noted above.
- Travel with it turned off
- Avoid carrying (spare) propane bottles. Connect accessory appliances to main propane system using Extend-A-Hose adaptors.
- Use Dog Bone adapters: Others generate too much heat with no way to dissipate it but through plastic around pins
- Use AC Polarity Checkers before hooking up and AC Test Meters to Monitor voltage. Avoid using sensitive appliances if voltage is out of range.
- Use proper 30 or 50 amp rated outdoor extension cords for your rig.
- Turn Fridge to GAS if on 15 Amp Service. Your Fridge AC heating element draws 160 watts (13 amps) so little is left for other appliances
- Inspect and Clean motorhome power socket. Check the back of it as well as the pins for corrosion. Coat with di-electric grease or fill rear with silicone sealer after ensuring all connections are clean and operating.
- Replacement sockets and connectors should be larger style with more pin area.
- Use di-electric grease on all 12V connections, bulbs, sockets etc to inhibit corrosion.
- Double Ground to chassis and battery the Towed vehicle ground wire. Ground at front to frame or common ground point and rear.
- Use isolating diodes for connecting towed vehicle wiring. Diode blocks in towed vehicles and "T-Connectors" on Tow vehicles.
Tow Vehicle Braking Systems
- USE THEM IF YOU TOW!
- All Provinces and 46 States have laws requiring these systems
- You cannot change the laws of physics. Often 6" is the difference between impact and a near miss. Compare how much it costs to replace a motorhome bumper and grille to the cost of a quality braking system
- Insurance considerations, renewal may be difficult
We recommend the SMI Vacuum Assist Tow Vehicle Brake System
- Supplies vacuum & operates using vacuum (Live vs. Dead Pedal)
- 10-15 Pound pedal pressure vs. 50-100 lbs.
- Positive brake application and Pull-Off (No brake drag)
- Coach Monitoring of tow vehicle braking
- G-Force controller allows user to adjust when brakes are on
- Break-A-Way switch included in every installation
- Full FIVE (5) year warranty
- Designed for User installation Takes 1-2 hours (Toll-free help line)
- Headlight "On" & "Signal" Beepers
- Day-Time Running Light (DRL) Modules
- Front Side Mounted Turn Signals
- Towing Bike Racks, Some fold down (great for rear diesel engine access)