Red light blinks? Just kidding but this is what you get when you don't give any details or full sentences. This is not a search site, we are human and can only give answers based on info you give us. Furnaces have code lights which are usually visible through a peep hole on the front panel. Look at your and record the color and number of flashes or steady lights. Open that panel and look for a chart that matches the code you saw, then come back here