Hi I have central heating and ac my heat worked a few weeks ago but I noticed at one point it was coming out cold so I put it up to like 80 degrees and it got warm I put my heat on last night and it was coming out cold even when I did put it up to 80 degrees nothing helped then at one point for a few minutes it came out a little warm not as warm that I know it can get because the house wasn't getting warmer so this morning the same thing it was coming out freezing and I keep playing with it up and down on and off and now its coming out warm not warm enough like it was a few weeks ago what do you think is wrong? Thanks

It could be a relay or a valve that is sticking or a bad heat sensor. We will need more details to help. Is the system a heat pump or a furnace? A heat pump is all electric with an outside unit up on legs that runs for both heating and cooling. The age, brand, and model number would help too.