Suburban DD-17DSI, Service Manual

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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 with Time Delay
Figure 22
P-40 with Time Delay