My furnace works on ac and blows on ac but on heat it does not blow but i hear a humming sound coming from the furnace

Furnace Troubleshooting & Repairs ' HomeTips

www.hometips.com/repair-fix/furnace-problems.html

Nov 25, 2015 - If your heater doesn't heat or works poorly, this furnace repair guide will help you troubleshoot and fix typical furnace problems with step-by-step advice. ... If your furnace's motor runs but the blower doesn't move air, the belt that ..... a tune upbut couldn't really find any thing wrong . last night and today when ...

Furnace Not Blowing Air? A Furnace Troubleshooting Guide

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Dec 1, 2014 - A furnace works by a very simple principle, it uses some type of fuel ...This series of heated coils (called a heat exchanger) has a fan ... Today we will address the most common causes of a furnace not blowing air, and what you can do tofix it. ... It seems like this would be a no-brainer, but I can't tell you how ...

Simple Furnace Fixes ' The Family Handyman

I take you mean there is a fan coming on that blows AC air thru the vents and is the same fan used to blow the heat ? If that is the case is the fan coming on when the heat comes on ? If not then that is why you are not getting the heat.
That can be from a temp sensor not working or a control board or a contactor
First see if the fan even comes on or if the same fan is used for both AC and heat

Blower motor & or capacitor bad

The fans heat speed is low speed and the cool speed is high speed. High speed is controlled by the fan relay normally open switch, the low speed is controlled by the temperature delay or time delay.
see diagram

If its a high or mid efficiency furnace most of the time the sequence of operation goes as follows: tstat calls for heat (R&W at tstat ) ventor motor starts, pressure switch closes, spark or hsi lights pilot or main burners. main blower motor comes on. From your description of a humming noise it sounds like maybe the ventor motor is seized.

The service technician probably installed a larger motor pulley which increases the fan speed to blow more air which results in a slight increase in duct noise which is normal.

If it does not have a furnace or heating elements for heating, then it is a heat pump, which is rare for a central AC system, but makes sense of the fact that it blows warm air when you reset the pressure switch, which may indicates freon pressure charge problem if your AC system has a reverse valve and uses freon to for heating (heat Pump).

Do you get heating when outside unit runs? if you do, check freon pressure levels and top up to required pressures. The button you depress is a pressure reset switch ... that is if your AC system is a heat pump ... which, as pointed above, it is not common for central ACs.

It Sounds You Might Have A Bad Heater Core,That Could Be One Reason You Have No Heat.

the fan you hear come on at a call for heat is most likely just the inducer motor. the click you hear is probably the relay for the hot surface ignitor which should glow red, then in turn ignite the main burners. your going to have to determine if the ignitor is coming on. if it isnt the ignitor is bad and will need to be replaced. if it comes on and than shuts off after a few seconds the ifc board is probably at fault

Sounds like your indoor fan motor is not working, check either the cap or the indoor fan motor it's self.