The leaves are turning, the temperature is falling, and you are hitting the switch on your thermostat from “Cool” to “Heat”.

You might be winterizing your boat, weather-proofing your home, and making other careful preparations to get through another Michigan winter. Before you get started doing anything with your AC unit or Furnace in advance of “the big switch”, we recommend reading this Q & A to make sure you don’t over-prepare (which is common) or under-prepare (which is costly).

Q: Should I Cover my AC Unit in the Fall?

A: It depends, but the answer is “probably not”. Covers aren’t really needed unless you are in one of these situations:

  • The unit is in a spot where the roof or a drain pipe leaks on it excessively
  • Debris falls on or piles up near it; i.e. it is near a tree that loses a lot of seed / small debris in the Fall or during windstorms
  • Your AC expert can provide really good reasoning for covering it outside of selling you a new cover.

Covers may seem like a good idea. You may think, “it will prevent wet leaves from falling through the grill”, “snow won’t leak into it and cause rust or corrosion”, “it will last longer if I protect it.” To the surprise of many, these issues aren’t a big threat – but covers CAN be.

Air Conditioning covers, especially those that completely cover the top, can cause condensation within your unit which has a far more disastrous impact on your unit than snow falling on it. Many covers will lock your unit down entirely and block air flow, which will cause moisture build up and corrosion inside the unit where it really matters.

If you still want a cover, or feel there’s a strong reason to use one, make sure you get one that is made from a high-grade, thick vinyl, and that it doesn’t cover the top completely – many new covers allow for ventilation, like those from Trane (although a Trane unit is built so durable and sturdy, with a weatherproof design, and there isn’t much need for a cover.)

In Stewart’s Experience: “We’ve actually had customers insist on using covers, then forget to remove their covers in the Spring when they first start the unit. It causes the unit to blow a fuse, and is a more costly service than us removing and cleaning whatever may have fallen on the unit in the cold season!”

Q: Should I replace my furnace filter?

A: Absolutely. If you stay on top of keeping a good, clean filter in your unit at all times, it heads off a lot of other problems.

A good rule-of-thumb is to check your furnace filter and change it out twice per year; Spring and Fall are the best bets. Even if you haven’t been running your furnace, your air filter has been put to work while your AC is on (unless you have a boiler or other special scenario.)

If for some reason your filter doesn’t look worn or as if it needs replaced, you can hold out for a month or two, but don’t forget to circle back around before winter is in full swing.

Remember: A clogged, dirty filter doesn’t break anything, but it makes your furnace work harder, makes the mechanical unit dirtier (which will require cleaning at some point to prevent problems), and it costs you more on your energy bill.

Stewart’s Tip: Call your Air Conditioning and Furnace expert to have them do a seasonal tune-up, or what they might call a “maintenance visit”. These visits are worth the price you pay to have the filter inspected and changed and to have a look at your furnace’s health prior to needing it for warmth in the upcoming cold season.

Q: I went to start my furance and it doesn’t seem to be working right (or isn’t working at all). What do I do?

A: We hope you tried to start it well in advance of needing it! There’s nothing worse than waiting until it’s cold to find out your furnace has a problem.

First, call your furnace expert and schedule a service appointment immediately so you can get on the books quickly and won’t be out of heat for long.

Second, check your pilot light. You might think it wise to check this first, however, you don’t want to waste any time in getting an expert to your home if it turns out the pilot isn’t the issue. If it turns out it is the pilot light, and you are able and willing to light it yourself, try that and see if you are able to get the furnace to work. If so, call and cancel your appointment.

Occasionally in the Fall when you go to kick on the heat and it doesn’t work it’s because something in the unit needs cleaned, a component failed somewhere in the off season, or in some rare cases, your flue is clogged and a sensor detects this, causing the furnace not to start; frequently this is due to a clogged flue, which can happen from debris, wasp / insect nests or birds.

Q: What other seasonal changes might I be forgetting?

A: One common missed “checklist item” is replacing batteries in your thermostat, especially if it is a programmable thermostat. We commonly say to replace them at the same time you replace your smoke detector batteries, unless you have special long-life batteries that might take it an entire year.

Q: What other crazy “weatherproofing tips” should I avoid?

A: We’ve seen one “trick” that makes us laugh every time we encounter it. If someone told you to put a large piece of plywood on top of your unit and put a rock or cinderblock on it to keep snow from building up on the unit during the winter, please – don’t. This is useless and can cause undesired side effects for your unit.

The only thing worse than this is tarping your entire unit and stretching bungee cords around it, or using duct tape / mailing tape to seal the entire tarp. Refer to the first question above for why this is a horrible idea (not to mention a terrible eye-sore!)


If you are in Southern Oakland County, call Stewart Heating and Cooling for a quick, friendly maintenance visit to keep your furnace running strong all winter long. Maintenance visits are inexpensive, can help avoid costly repairs / problems and heat outages, and give you a peace of mind that is priceless.

Call (248) 549-0400 to schedule a Fall maintenance visit now!