POP goes my Lennox!

[andyvh1959]

As in AC unit. I was outside in my shop, about 30 feet from the Lennox AC unit that cools my house. Y'know that feeling when you smell that "hot electrical" scent? I heard a distinct "POP!" like a dud cherry bomb going off. Again, the smell, so I walk to the front of the house, thought maybe its the utility service truck on the street. Nope, as I walk back to the shop I see smoke curling out of the central AC unit, so I rush inside to the breaker panel to find the 30 amp breaker had already tripped. The side panel of the AC unit near the electrical is so hot I cannot put my hand on it. Something seriously shorted out, still smoking and very hot. I took the top off the AC unit to find burned insulation on the wire, and a few small flames I blew out.

So I called the HVAC service shop and I'm on their list for service tomorrow. My central air is a Lennox HS29-411-IP 3-ton unit, at minimum 20+ years old and never failed or quit till just now. The POP was the Motor Mate (beer can sized) capacitor that which blew apart. The fan motor still spins, and who knows how the compressor might be. I looked up MotorMate capacitors and it looks like they have a regular fail rate, so perhaps its only a bad capacitor. But the pics attached show more damage than just a capacitor. So I likely have a brand new AC unit purchase tomorrow. Question is should I stay with a 3-ton unit for my 2,950 sq-ft house or go up to a 4-ton unit. My house is a 1973 tri-level with two heating/cooling zones.

 

[PoorUB]

If the 3 ton cooled fine no reason to believe a new 3 ton will not cool as well. Also you need to consider duct work. You can't shove 4 tons of cooling down duct work sized for 3 ton.

 

[andyvh1959]

Good point, thanks.

 

[reader2580]

You don’t want to oversize an air conditioner, especially in Green Bay. A larger system won’t run long enough to remove humidity unless you get a fancy multi-stage unit.

A good HVAC contractor should run calculations instead of just installing the same size unit again.

 

[Hobby_Man22]

Mine runs 7-10 minute cycles and keeps the humidity around 60 percent. Now if you bump it up to 81 or so then the humidity level will go up regardless.

 

[American Locomotive]

Just a couple exploded caps and some melted wires to the fan motor. They'll probably try and sell you a whole new system, but I'd bet a new fan motor and new caps will get it up and running again.

 

[andyvh1959]

I'm sure they'll try to sell me a new unit, which I might consider given this one is at least 20 years old, and Lennox has some good rebate deals. Its the same unit that came with the house when I bought it in 2002. However if a new capacitor and rewiring will get it done, I'll be good that way. The fan spins easily, so I'll have them rewire it and check if it powers up. I can clean the base out and clean the evaporator.

 

[Jackfre]

You got a tech out in one day? You must have pictures. Repairing a 20+ unit is throwing good money after bad. Buy the multistage unit. You will be happy you did.

 

[TractorJeff]

Post 8 Yeah, if you have about 8 Grand to spend! This is the wrong time of the year to decide on a "Fancy Multi-Stage Unit". I would be tempted to go with a new Cap and Fan Motor!

 

[Showkey]

I am in the same climate zone as Green Bay.
No way I would spent up for multistage cooling……….multistage heating……..maybe YES. Even then there’s no real saving on multi stage but in home it’s more comfortable and quiet. In shop not really needed.

This year is slightly hotter than years past…….we are at 7 plus 90* days to date. The average is 5 for the entire year. There have been years with 0 90* plus days in the last 5 years.

Yes, we often run the AC to get the humidity levels down. Plan Jane AC proper sized unit will run for another 20 years.

DIY CAP replacement and wiring repair is very possible for some GJ guys.
CAP can be found to $10-$50.

YES,,,,,there might be other problems like the compressor failed.q

 

[andyvh1959]

Just got quotes from the local HVAC company I've had good history with for 20 years. This Lennox unit was installed back in 1995, and uses the old refrigerant that goes for $100 per pound. If I replaced the capacitor myself and replaced the burned wiring, assuming nothing else is wrong I'd into less than $100, but on a unit approaching 30 years old. Even if I got the old beast running again, I'm looking to sell this house within five years, a much newer AC unit is a selling point, along with a new Lennox furnace just eight years past.

If there is any need to replace the compressor, lets say its the cause of the capacitor literally exploding, I'm at $700 plus just to flush and recharge the system. Sales guy says the 1995 Lennox was about an 8 SEER. He quoted me a 3-ton Lennox ML14XC (13 SEER) installed for $4718, a Lennox EL16XC1 (16 SEER) installed for $6113, or a Lennox XC21 2-stage 20 SEER for $9453, yowsa!

So, bit the bullet, getting the EL16XC1 installed next week Thursday, 18 months no interest financing through the HVAC dealer. Luckily the weather has turned real cool today, and only in the low 80's through Sunday, mid 80's till next Thursday. Open windows time.

 

[chrispyny]

Honestly, a 16 seer brand new unit installed in the middle of summer PLUS all your other reasoning to do so is NOT BAD for $6,113.

Normally, i’d throw the $100 in caps and parts at this to see if i could get it running, but ONLY if my A/C dealer told me i could save a grand off the install if i waited till end of season, or if it were brutally hot and the family was riding me hard to fix it ASAP. It’s a $100 gamble i’d try to save a grand. Worst case your out of pocket $6,213 instead.
In your case, assuming it wasn’t discussed, I think you made a wise choice.
New a/c, at double the efficiency, installed within a week of yours conking out, for roughly 6 grand for a 3 ton unit? Sounds fair to me!!

please take before and after pics, and come back with results. We all wanna see your new set up!

let this be a lesson to anyone who has old caps in their units. Caps are cheap and plentiful. I’d be swapping mine out every other year if i were running an older a/c!

 

[andyvh1959]

Thanks for the reply. I'm also in a time crunch, as I have to work this weekend doing motorcycle training classes, and then out of state for work for a week. If I did get it running again and then something else goes while I'm out of state, makes for an unhappy wife. All things considered I felt it best to go ahead and update the AC. And like I said, when we sell the house the furnace and the AC unit will both be up to date within ten years instead of being 30+ years old. Sales guy also said the new AC unit will work better with the newer furnace then did the old AC unit with the new furnace.

Couple other things; the dealer had all the components on hand to get the project done, the cost includes a new, larger A-coil in the plenum above the furnace, and a bigger plenum. Includes flushing out all the current refrigerant in the 35'+ of line from the A-coil to the compressor, and possibly even installing new lines from the new A-coil to the to the compressor. a new larger pad for the new AC unit.

 

[LS6 Tommy]

Just a couple exploded caps and some melted wires to the fan motor. They'll probably try and sell you a whole new system, but I'd bet a new fan motor and new caps will get it up and running again.

X2. I'd check the compressor impedance and if it was OK, replace the bad wiring and electrical components.

Tommy

 

[andyvh1959]

 

[captain14]

Keep us updated on the HVAC upgrade. And your thoughts after everything is up and running.

 

[bonneyman]

Hell if I was in your area I'd come and remove your old condensing unit - and give you $200 for the opportunity. Then take that sucker home and rebuild it. So long as the coil is sound everything else can be replaced - and I could use it on my enclosed garage project that I'm considering.

 

[andyvh1959]

Given your comments I'm inclined to tell the HVAC guys to leave my old unit on site and I'll see if I can resell any of it on CL. The coil you refer to is both the A-coil and the large evaporator on the outside unit correct? The compressor was running fine and no leaks. I'm pretty certain the relay failed closed and the start capacitor stayed on even after the compressor started and kept getting hotter, like the youtube video indicated.