W Iring Diagram S - Suburban DD-17DSI Service Manual

Customer complains of unit going into lockout only once in
6.
a while:
a. Thoroughly check electrode and burner relationship.
b. Lockout can occur if the gas pressure fluctuates at the time the
thermostat calls for heat. Pressure fluctuations can be caused
by a malfunctioning gas bottle regulator, an obstruction or a kink
in the gas line, or moisture in the gas bottle regulator or in the
gas lines. It is difficult to check for these fluctuations that will not
noticeably affect any other appliance in the coach. However,
isolating the furnace from the coach gas system will determine
if the gas system is responsible. This isolation procedure can be
done by connecting a separate upright bottle, regulator and gas
line directly to the furnace, eliminating the coach gas system. If
the occasional lockout still exists, then the furnace should be
thoroughly tested to determine the cause; however, if the
furnace works properly on this separate system, then the coach
gas system should be checked.
c. Check furnace return air and warm air discharge to be certain
sufficient air flow is present to engage micro switch every time.
d. Check micro switch to be sure it moves freely.
e. Remove electrode and burner. Clean thoroughly.
f. When moisture in the gas system is suspected as being the
problem, especially where the horizontal type gas bottle is being
used, the following steps should be take to prepare the gas
system against further moisture problems:
Corrective Measures:
1. Disconnect gas bottle and drain it completely dry of all gas
and all moisture.
2. Disconnect and blow out all gas lines completely dry.
3. Check pressure regulator on the gas bottle. Replace if
necessary.
4. Add the drying agent. One half pint of methanol alcohol per
100 pound bottle capacity is recommended.
Precautions:
5. Never fill the gas bottle over 80%.
6. Do not use the gas bottle completely dry to avoid using up
the drying agent.
We have found the above procedures to be effective in solving
most occasional lockout problems, especially where the
horizontal type gas bottle is used. All of these steps must be
performed as described for the preparation of a contaminated
gas system to be 100% effective.
Figure 21
P -30S w ith Tim e Delay
Figure 22
P -40 w ith Tim e Delay
30