Hello I have a Dearborn model 65 kbps wall mounted furnance. I recently purchased the house and no one knows how to turn it on. The gas relay has On and Low markings with a dial. There is a red button on the side. No markings for pilot light. Does anyone know how fire up this model furnance... It also has a wall thermostat. Thanks

New user, looking forward to helping a single grandmother in my community get back to a warm home! Unit: Rheem RGPH-07EAUER horizontal installation Symptoms: Furnace fully ignites and runs blower with warm air being sent to house, but shuts off gas after 5-7 minutes. Confirmed multiple times control board does NOT indicate any failure codes (no blinks at all, just flame sensor LED de-energizes). After gas shutoff both inducer and blower motors run proper shutdown sequence, then process starts over again. Checks: Removed thermostat and wire-nutted RH and W wires to ensure thermostat is not issue. Cleaned flame sensor, no change. Unit detects flame properly (LED energizes) upon flame-on. Cleaned supply/return registers, fully opened, slightly longer runtime. Ran unit fully open with finger on blower door switch, no change. Confirmed flue outlet is clear of obstructions Diagnosis is unknown, but it seems like a limit switch issue with overheating either the coil or the discharge air, or just a bad limit switch. Ready with a multimeter to start diagnosis, but want to confirm what I am looking for. Grounding, looking for continuity between inducer fan ground connection and furnace body. Furnace limit switch - do I watch ohms for anything except 0? Flame rollout limit switch - do I watch ohms for anything except 0? Inducer pressure switch operation - check for continuity once inducer fan is running, any OL is failure? There does NOT seem to be a limit switch on the flue stack, but perhaps I am missing where it might be It does not seem like there is any dirt/dust/grime in the burner housings and minimal dust on the squirrel cage blower, everything looks to be clear. Thanks for any help you might be able to provide! Kevin