Service manual

06/2010
7. The RV500 will not increase the flame above minimum until a flameproof signal is sent to the
circuit board by grounding the red lead attached to the spade connector on the DSI board.
You can do this manually by touching the metal portion of the red wire to the RV500 steel
case. The flame should increase.
8. Check thermisters per the section 4.5 ‘T-in, T-mid, T-out Thermister and T-set Readout’.
9. Check DSI harness 1829 red wire for continuity between the circuit board and the DSI spade
connector (see figure -4).
10. Change the circuit board 1841-RV. (SM500-01).
11. Check the heater for airflow obstruction and clean.
3.8 Large fluctuations in temperature
1. Are you operating on the water pump? If yes, check if the flowmeter (or water flow) is pulsing
at a low flow. If YES, then you may need an accumulator. See the section 4.4 ‘Using the
water system pump’.
2. Are the inlet and outlet water supply lines hooked up properly? Check that all screen
strainers and filters are clean and not obstructing water flow. The water inlet connection is
the upper and the water outlet is the lower. This is the opposite of hot water tanks. You can
also check the direction that the flowmeter rotor is turning. It should turn counter-clockwise.
3. There is a built in check/pressure reducing valve in most newer coaches. It is built into the
hose hookup assembly. To locate it remove the water supply hose and the strainer/washer.
Now, look into the water inlet. You typically will see a plastic spring retainer.
By putting a small screwdriver beside the spring retainer and turning it you can increase or
decrease water flow. By turning adjust this check valve so that your showerhead, on full hot
and no cold water running, makes the green LED on the water heater blink 12 to 16 times
between interrupts during the summer and 8 to 12 blinks during winter operation or when on
cold well water.
When moving from campground to campground you may need to readjust the pressure if
you experience hot and cold cycles. This would be due to drastic changes in supply water
temperature from campground to campground.
Do not make the above water pressure adjustments unless the showerhead flow-
restricter has been removed!
To remove the showerhead flow-restricter, take the shower hose off the showerhead. Look
into the water inlet of the showerhead. You will see a white or gray plastic part with a small
hole in it. Turn a screw in to the hole and pull out the small plastic part with a pair of pliers.
4. Is the flame cycling between minimum burn and off? If yes, check the water flow through the
unit as described in section 4.3 ‘Reading flow using the green LED’. Then refer to figure -1
to verify that the water flow is above the minimum normal operating line. You can do this
step only if the last letter on the micro-controller chip EL 9049 is version ‘D’ or later.