Dayton gas furnace model 3e385 works and lights but as soon as fan comes on the unit shuts off and lights again wondering what was wrong

Does unit fan come on ??? Is flue clear as most units have a safety klixon if exhaust not venting properly.

Check the flue for a restriction

Hi,

Sounds like the blower motor is bad and then the unit is kicking off on high limit....

Probably nothing you can do with out getting a new motor to replace the bad one...

heatman101

I'm not sure whether this is a gas unit or not. With many gas heaters, the blower comes on when the heat exchanger gets hot enough and goes off once the heat exchanger cools. Other things are happening before the blower goes on. The blower is normally controlled by a "fan control thermostat". This stat actuates the blower when the furnace is hot enough so that cold air is not being blown around and allows the blower to run until the furnace cools enough to get out the remaining heat after the flame shuts off but not so long to again allow cool air to blow around. If this fan control is malfunctioning, you will get erratic runs from the blower or the blower may not run at all or run long or continuously. The fan control is the first thing to check.
Gary

Check the high and low snap disk and check wall thermostat if fitted.

This problem is caused by a bad flame sensor (looks like a spark plug) which can be cleaned by sanding or with steel wool.

Hopefully someone with more experience will respond as well, but my experience with this type of furnace is that this is likely to be a clogged line or gas feeder control device. The behavior indicates that there not enough gas being presented to the unit. Unfortunately this is NOT a DIY type of repair. A licensed plumber should examine this unit. Gas units can be dangerous if not serviced properly. Please seek local assistance frmo a professional.

Dan

When your furnace starts...the Ventor motor(exhaust fan) starts up....within a short time (seconds) the Pressure switch closes proving that the Fan is indeed running and the vent is not blocked...if this doesnt happen the furnace will not poweer the ignitor or fire at all....Check the vent pipe outside and look for obstructions or dirt on the screen inside the pipe...the condensate from the fuirnace may not be draining at all...due to plugged condensate drain lines...find this tube coming out of the furnace front...bottom of upper compartment usually , and pull it off the tap....if water starts coming out then your drain is plugged downstream of the furnace.

This happens when the furnaces tries to light to many times and doesnt succeed. If you stand in front of the furnace while it is coming on, you will be able to hear the problem. If its an electronic start, there will be a clicking sound, followed by the gas valve opening to start it. If it has a pilot light, make sure it is lit, then listen for the gas to come out, it will make a hissing sound. If no gas is coming out, first double check to see if the gas is turned on to the unit, if it is, then its possibly the gas valve. Oh, if it is electronic, and you hear gas, but dont see a glow inside the furnace, or no glow or gas, it could be the ignite. Hope this helps.