I had a new Weather King Furnace installed approx 18 months ago and a new climate technology thermostat as well. This is really the first time I've had to use the heater. The Furnace comes on for approx 30 seconds and shuts off. The A/C unit works fine. Any suggestions?:(

Behind the door on the furnace you should find a circuit board ,or control moduel with a red light,, if it is blinking (coding) count the blinks and the paper gled to inside of door will tell you what the codes mean and what to look for. This is if you have a gas furnace,which you didn`t say

To help you understand any control codes, check the sequence of operations in the sticky at https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313.html