The odds are against you having a total system breakdown if you skip one cleaning but that increases greatly with continued neglect as moving parts wear out and dirt accumulation makes the HVAC system work harder
If you play roulette, the choices are playing American style or European style. The American roulette wheel has an extra slot, the green double zero. It decreases the odds of any number coming up on a single spin to 2.63% (1 in 38) from 2.70% (1 in 37) so the “wise” choice is to find a European wheel. If you do hit on a single number, your payout is only $35 for every $1 bet so the best roulette advice anyone can give you is to stay away from the wheel and enjoy a nice meal at the casino buffet. There’s a third style of roulette that involves no cash transaction and the odds are about 83.33% (5 in 6) that you will escape unharmed. If you do lose at Russian Roulette, your family may be able to collect your life insurance assuming your policy covers loss of life from an accidental gunshot. No one in their right mind will willingly play Russian Roulette but Americans do take a risky gamble every time they decide to forego their semi-annual HVAC cleaning and tune-up. The odds are against you having a total system breakdown if you skip one cleaning but that increases greatly with continued neglect as moving parts wear out and dirt accumulation makes the HVAC system work harder. The odds are higher that, in certain climates, mold and mildew will form in the HVAC’s ductwork making your house smell like a pile of dirty socks. The real danger is if your furnace’s heat exchanger begins to leak due to the constant contraction and expansion when the furnace is in operation. Carbon Monoxide is just as lethal as that bullet sitting in the chamber of that pistol waiting for someone to play Russian Roulette.