A power-vent heater's running blower does not prove that the burner can ignite safely. The control must satisfy its model-specific operating and safety conditions. Record the exact status code and have persistent failure checked for the permitted vent, pressure-switch, ignition or gas-supply causes. Never bypass a switch or open the sealed combustion chamber.
Start with the exact model and status message
Read the accessible display or status light and record its full pattern. Do not use a flash chart from another gas valve. The cited Rheem power-vent manual provides different status-code tables for its listed control types, including pressure-switch, blower thermal-switch and failed-ignition conditions.
Those entries identify checks for qualified service personnel, not a single part that must always be replaced. A pressure-related message can require examining wiring, the vent system and the blower arrangement. A failed ignition trial has another diagnostic path. Copying a code count from a different control can send the repair in the wrong direction.
Keep safety devices in the sequence
Do not bridge a pressure switch, reset a thermal device repeatedly or remove the sealed burner door to make the heater light. The manual states that burner, vent, ignition and safety-device repairs belong to qualified service personnel. Altering a proving switch can allow operation without the condition it is intended to check.
Look from a safe location for an obvious change near an accessible outdoor vent termination, such as stored objects or visible damage. Do not climb, detach the vent or reach inside it. Report what you see. How a gas water heater is vented explains why the complete vent arrangement matters.
Know when to leave the area
If you smell gas, leave and contact emergency services and the gas utility from a safe location. Do not operate appliance controls or electrical switches inside. If a carbon monoxide alarm sounds, move outside to fresh air and obtain emergency help. CPSC's carbon monoxide guidance warns that fuel-burning appliances can produce this odorless gas; a running blower is not a safety test.
For recurring shutdowns after operation starts, see a gas water heater that keeps shutting off. A pilot outage with a gas smell needs the gas-emergency response first. For a blower without ignition, give the technician the code and sequence rather than trying replacement switches or relighting indefinitely.