Air handler blower door location & operation:
How to find the blower compartment door on an air conditioner, furnace, heat pump air handler or blower unit, and how to open or close and latch the cover.
Safety warnings about opening the blower compartment on an air handler unit.
Green links show where you are. © Copyright 2017 InspectApedia.com, All Rights Reserved.
[Click to enlarge any image] In the sketch above, provided courtesy of Carson Dunlop Associates, a Tornto home inspection and education firm, you can see the blower unit of a forced air heating furnace in the left side of the sketch. The blower compartment access door for this unit is probably on the "back" of the unit that you can't see, around the corner of the left side of the unit that you can see in the illustration.
2016/08/14 Linda said:
Where is the blower door located at ?
I've added some photos and created this article to help you see what you're looking for when you need to find the blower compartment access door or cover on an air handler.
The "blower door" is found on one side of the blower assembly. In my photo below, a handle opens the entire side of this air handler installed in the Watergate apartments in Washington D.C.
For air handlers or blower units intended for consumer access, such as to change an air filter, you'll see a handle that un-latches and opens the blower compartment.
If your air handler or blower assembly (the indoor unit of an air conditioning or forced-air heating system that contains a blower fan and connects to ductwork) is also a heating system, usually the blower door is on the opposite side of the air handler from that where you see the oil or gas burner that is used when there is a call for heat.
The interior of the residential air handler shown above is accessed in two stages.
The taller upper cover (1) is lifted up and out, or simply outwards. Some vertical air handlers on air conditioners and furnaces use screws located along the sides of the unit to secure the upper cover in place while other units have a cover that can be slid upwards about an inch, then pulled outwards. A flange on the cover bottom secures the lower edge of the cover in place when it is replaced.
The shorter panel at the bottom of this air handler (2) will lift up and out once the upper cover has been removed.
Above: in our first photo, the air handler, jammed into a closet, provides a single access cover to its interior. The cover is held in place by four screws seen on the front of the cover and circled in red. Our second photo above shows an air handler access cover held in place by two thumbscrews near the top of the cover access panel. Below, using a different and possibly unsafe air handler installation we see the unit with its upper cover removed.
I was concerned to see an inlet in the return air duct for this gas fired furnace in a location (upper right in the photo) where it could draw combustion gases into the building air - risking a fatal CO poisoning hazard. I was also concerned about the rust at the air handler bottom: further inspection was needed to decide the safety of this unit.
In the photo below I'm opening the blower door on the rear of a forced-air heating furnace. Notice the very dirty, debris-blocked air filter. More about finding the air filter and other photos of air handlers are at AIR FILTER LOCATION.
On a horizontal air handler such as we might find in an attic and shown below, an access door will more likely be secured with screws not a handle, as the air filter is located elsewhere (such as at a more -accessible return air inlet grille) and the consumer or homeowner is not expected to open this machine.
In the first photo above access to the air handler interior will be behind both of the screw-secured panels on the face of this unit. Our second photo shows the air handler interior both covers removed. On the left side of that second photo you can see the blower itself behind a panel containing a circuit board and a morass of wires. .
In my photo below you can see the access cover removed on a different air handler unit.
Above you can see the heavy door and thumbscrews that secure it on a commercial-grade rooftop air handler. Notice that I've opened the electrical box at the lower left in this photograph. I needed to turn OFF the power to this unit before it would be safe to open the blower compartment door. My second photo shows a close-up of the latching thumbscrew on this rooftop air handler - in the closed position.
Watch out: do not attempt to open any air handler with the power on. There are shock hazards, and moving parts can cause you to lose a finger or hand or otherwise to be seriously injured.
Above I've opened the hinged cover of a commercial rooftop air handler to expose the bllwer compartment. Because it's exposed to weather this cabinet is weatherproof and the hinged blower compartment door sports a weather-proof gasket and thumbscrews (photo left side) that tighten the door against leaks.
Watch out: if your blower unit or air handler has electrical power but won't turn-on, and provided that your thermostat seting or FAN setting should be causing the unit to run, the problem could be a loose blower door cover that is not properly contacting the blower door interlock or safety switch.
Or see AIR CONDITIONER WON'T START
Or see HEAT WON'T TURN ON
Continue reading at BLOWER DOOR SAFETY SWITCH or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see AIR HANDLER / BLOWER UNITS - home
Or see BLOWER LEAKS, RUST & MOLD
Or see FURNACE CONTROLS & SWITCHES
Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website