DSI fireplace: ignitor sparks but burner will not light

What is going on

Spark is present but the burner never lights; on RAM 1MC1 modules it sparks for 4 s (-01) or 7 s (-05) then locks out.

Likely causes

• Gas shut-off closed
• Air in the gas line
• Obstruction at the gas valve
• Burner ports covered by embers
• Plugged burner orifice
• Ignitor not over the burner port holes, or sparking at its base
• No voltage to the gas valve, or failed valve
• CFX-DA: combustion blower not running or open high-temperature limit

Check in this order

1. Make sure the gas shut-off is ON and purge air from the line.
2. Clear any obstruction at the valve, reposition embers off the burner ports and clean the burner orifice.
3. Adjust the ignitor bracket so the ignitor sits over the port holes; the spark must jump at the tip. A cracked ceramic or spark at the base = replace the ignitor.
4. 120 VAC modules switch ON, measure MV to MV RTN on the module, expect 110/120 VAC. Present but valve stays closed = replace the valve; missing = replace the module.
5. Fenwal 24 V: measure 24 VAC at V1 and V2 on the module. Missing = replace the module; present = replace the valve.
6. RAM 1MC1 valve wiring terminal 1 (white) to 3, terminal 2 (blue) to 4.
7. CFX-DA the combustion blower must run (it needs outside air via the AK-CFX kit, and the air duct must never elbow down). No 110/120 VAC across MV/MV RTN: check the high-temperature limit, which on this unit is normally closed and must have continuity; blower not running with power at it = replace the blower; blower running but no valve voltage = replace the module.

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