Blower fan will not come on when set on Auto in heat mode.
Old Rudd unit works fine but when I cleaned up for the winter heater find the fan will not come on when set on auto. The burner unit fires up but after burning for short period goes out when time for blower fan to come on. Works ok when fan set for ON. Works fine when in AC mode.
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Re: Blower fan will not come on when set on Auto in heat...
The fan is controlled by a fan center or a stack switch. as burners light and heat up the spring sensor on the bulkhead above burners heats up and turns and a a point energizes the indoor fan if it gets to hot the burners go out on safty. sounds like a fan control is bad tap on them gently and they sometimes break loose but if not then have a pro replace fan control and test heat exchanger.
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It is either the element, sequencer (or contactor/relay), or power to the switching element. 5KW Elements normally Ohm out @ around 10 Ohms when they are good. Everything you need to check requires a multimeter.
Wish I knew how old your furnace is. Let me answer your question directly. In the heat mode the fan runs independently from the air conditioning fan relay. Its either brought on by time or temperature. An old furnace will use a fan and limit control that uses a coil to sense the heat exchanger temperature and turn the fan on or off. Newer furnaces use a timer on a circuit board. 20 years or newer Ill bet its a timer board. Follow the blower motor wires back to the component and ill bet that's the culprit. Hope it helps. Good luck.
Maybe turn selector switch to off.see if every thing shuts off.if yes. turn FAN selector switch from (auto) to (on) mode.does the outside unit come on or does just the furnace blower only run ? the inside fan should be the ONLY thing on.if not, reverse the (G) & (Y) wires inside the new thermo.
The model of T-stat you gave comes up as a discontinued model on Honeywell's web site, but it looks to be a manual stat that type of stat would have to be wired with a summer winter switch with electric heat, allowing it to turn on the fan with a call for heat. If yours is a programmable T-stat you would need to select electric heat or in the installers set up change the default setting for fan from unit controls fan in heat to thermostat controls fan.
Okay did you check your thermostat to see if you have the fan switch on auto? The switch must be on auto or the fan will continue to run. If the thermostat fan switch is on auto then there is a malfunction in the thermostat probably. You can go to your forced air unit and on unplug the unit. That way it will not turn on at all, because the forced air unit is controlled by the thermostat. Hope this helps.
You have a blower relay in the furnace that's probably bad. In the heat mode the blower is on a temperature relay, in cooling mode the blower has to come on immediately so there is another relay for cooling. The green wire on the thermostat feeds that relay, so if you go to the furnace and shut the power off and find the green wire from the thermostat that feeds that relay and replace it, being careful to mark all the wires before removing them, also the relay terminals have numbers for identification.
The blower has absolutely nothing to do with outdoor air. Having the T-Stat set to auto lets the blower come on only when the A/C-heat comes on. With the switch in the ON position the blower simply runs all of the time. Depending on your living space (high ceilings, multi-level) having the blower on constantly while costing a small amount to run can actually save some money and make you more comfortable in the summer. However most people will leave it in auto in the winter so they don't feel as if they have a draft from the air movement as the blower is in high speed in fan on position and cool modes and low speed in heat mode. Many furnaces today are equipped with a setting that allows the blower to run constantly at a lower speed or simply run for a min. or two after the A/C=Heat have turned off.