A/C Blower Motor Event

Upon returning from a 11 day vacation (I’ll write about it later), I found that the house was 92 degrees inside:

This was despite a thermostat set at 85. My kitties weren’t happy!

Listening closely, I could hear refrigerant gurgling through the evaporator despite no fan.

Oh, no!

I shut the system off. Later, after inspecting the electricity meter, I found that the compressor ran almost constantly, chewing through about $190 of electricity before I caught it.

Here’s all the ice that formed on the evaporator coils (the part inside the house):

I could hide a penny in the ice:

Here’s all the water (and mold!) that accumulated next to the evaporator:

Yuck!

Ice even formed on the refrigerant return line:

Yes, ice was even on the refrigerant line outside in the upper 90s heat!

By the time I took that picture, most of the ice already melted off. The system had been shut down for a few minutes. The bottom of the condenser had a lot of water, suggesting that even the entire condenser was cool.

This is after I used my shop vac to vacuum most of the frosty ice off one side:

The ice in the very rear was solid, clear ice. I pulled that off by hand.

A new neighbor in the A/C business came by and helped me confirm that the blower motor died. He helped start it back up by manually turning it while switching on the thermostat.

Note of caution: those fan blades can eat fingertips when it’s moving. Be very careful doing this!

After unpacking the car, we left for supper and shopping. Returning about 2½ hours later, the fan had shut off again. It could not even maintain speed!

Fortunately, I already had taken off the next two work days, so the following day was spent replacing the fan.

Here’s the furnace. The blower assembly (fan) is in the back:

The blower assembly removed removed:

It’s so dirty partly because the previous owners used a low quality reusable filter resembling a thin wicker mesh coated in some blue substance. Very ineffective, and actually very costly, considering that a new blower costs a lot more than the value of a few saved filters. I could smell their nasty cigarette smoke while I was disassembling it.

Here’s the fan housing later all taken apart, with the blower separated from the squirrel cage:

Between figuring things out for the first time and dealing with a squirrel cage fan that didn’t want to budge from the blower motor, it took me about 45 minutes to do this. The bricks were used to support the bottom of the blower housing while I banged on the blower motor shaft to separate it from the fan.

At that point, I took the blower motor to my local Grainger Industrial Supply for a replacement.

Grainder technically doesn’t sell to the public; you need a business account. Fortunately, the salesman was nice enough to use my employer’s account. (I need to print up some DBA business cards so that I can register myself next time I come across this!) About $75 later, I walked out with a replacement fan and capacitor. (The capacitor sends a surge of electricity to the fan to start it up from a stop.)

Now here’s where things got a little hairy. The original Carrier furnace had a special connector to connect its primitive logic circuitry to the fan:

I knew I could rewire this, but I figured it would be best if I could find a similar connector so that I didn’t have to cut everything up. The original blower motor was permanently connected to this part, and the new blower motor just had wires ready to be crimped to something.

After a wild goose chase involving a nearby electrical parts supply, an air conditioning supply, and a motor supply house, I decided to just rewire it using standard blue butt crimps.

The new blower motor had a broken oil port cover:

Easily fixed by a dab of black RTV, left over from my Nova days:

Another problem with the motor is it had four studs that protruded way too far:

My Dremel and a cutting disk fixed that:

Test fitting the blower motor and the fan:

After about an hour of cleaning the grime and cigarette residue out of the fan and the case and reinstalling the fan assembly into the housing, I ended up with this:

Ready to be tossed back in the furnace! By the way, it was difficult to get that to fit correctly. The three arms slide into a band that is cinched around the motor. You had to hold your jaw “just so” to get it all in the right position as you tightened the band whose bolt and nut were barely accessible! That was frustrating.

Empty furnace:

Furnace with fan and wires connected using butt crimps:

My special tool to keep the door switch depressed while testing (the neighbor taught me this one!):

I got the fire extinguisher ready, crossed my fingers, turned on the thermostat, and IT BLOWS! Even though this is almost an exact replacement–almost identical specifications as the old fan–it blew much more strongly. That old fan must have been ready to go.

I can already tell this new blower has improved air conditioner performance. Temperatures are somewhat more consistent in all rooms.

The best part is I only gouged one finger:

It bled through three band aids before it came under control.

I spent the next evening sealing up a major air leak in the system. This air leak pushed nasty crawl space-smelling air into the living area of the house. The bad thing about this leak is it was across the width of the unit in the very back, where the furnace sits on the evaporator housing. (Basically, the thermostat housing’s bottom opening protruded about 1/2″ past the edge of the evaporator housing.) 2 hours of fun with foil tape and improvised tools got the leaks mostly sealed up, at least well enough that I don’t get crawl space moldy stink in my house every time I run the A/C.