central air unit blowing hot air - capacitor replaced

[GON]

Driving home from a week out of state yesterday (Saturday), Wife stated one of two central air units is not working, one thermostat is reading over 80 degrees.

Arrived home 1am this Sunday morning. Got to work on the issue after waking up. Watched two youtube videos on capacitor diagnostic and replacement. Went and checked the unit out, and off to Home Depot for a replacement capacitor.

Everything was extremely easy. Less than an hour from start to finish, including a run to Home Depot. Only issue was old capacitor didn't have the terminals labeled. Easy solution- on the capacitor, one terminal has two lead, one terminal has three leads, one terminal has four leads. So used the lead numbers as the key. If I didn't have that to go with, I would have pulled one terminal off to isolate the fan, then I would have reduced the amount of error risk.

Numerous stories point that a service call to replace the capacitor can easily run $300-$500. I didn't know how long the wait is for a technician. The capacitor before tax was $18. (I don't know why the label price was $24).

Finally, I want to thank the BITOGER that started a thread that Home Dept sells capacitors. I did a search but couldn't find his thread. His thread triggered me to go to HD for the capacitor. I would not have thought HD sold them. BITOG has hundreds of active and positive contributors. And about a dozen trolls/ baiters. Glad the HD capacitor thread starter posted, rather than not post because of the trolls/ baiters. The capacitor thread starter saved me hundreds, and who knows how long for a technician. And maybe the technician might not be honorable and try to sell a replacement unit in the thousands. Had the trolls/ baiters discouraged the HD capacitor thread starter from posting the thread, my morning may have gone very different- thanks HD capacitor thread starter!

Supplementally, purchased an air filter while at Home Depot. HD quit selling 3M filters, the sell HDX filters that are packaged to look like 3M filters. These HDX filters are very pricey; the filter was just .50 less than the capacitor. I will be buying home air filters from Wal Mart from now own.

 

[The_Jeff]

Glad you have redundant AC systems. Two is one and one is none.

 

[Lubener]

The contactor to the right of the capacitor will be the next item to fail. Get in the habit of changing both every five years and you likely will won't have a problem with your a/c. for some time to come.

 

[Mackelroy]

I didnt know HD carried capacitors. but its around $300 repair if you call a company. I normally keep one on hand and order online.

and you get a crap cap calling a company, thats normally generic for multiple units and doesnt last 2 years.

 

[dishdude]

I had something very similar happen a few years ago. 6:30 PM it went out, did a quick google search and saw the local Ace had them and closed at 7. Decided to just run over, grab one and toss it in. Been working fine for years. This fall I need to replace it and the contactor, I doubt it will last another year.

AC capacitors and car batteries only last 3-4 years in the desert.

 

[amateurbob]

This happened to me last year. My ac went out on a Sunday evening and I called 2 hvac companies based on recommendations. Neither one returned my call. I did exactly what @GON did. I looked on YouTube and diagnosed it was the capacitor. I had to wait until Monday morning because home Depot didn't have capacitor in stock.

Since l am novice it was much more anxiety inducing.

I don't know if l am an old man screaming about his lawn but the part was $15 plus tax and the companies would have charged me $450 to do it. Assuming 2.5 hrs labor and drivetime... Thats around a $172 an hrs for 2.5 hrs start to finish... And the guys weren't interested.

 

[RBT]

As my wife would say, you get a notch in the husband card. Good job!

What does the capacitor do exactly? Thx.

 

[The_Jeff]

Caps help motors and compressors start, they take a huge inrush current.

 

[GON]

As my wife would say, you get a notch in the husband card. Good job!

What does the capacitor do exactly? Thx.

Thanks.

Last time I studied capacitors was 1984/1985. From my memory, capacitors store electricity, like a battery. A home AC capacitor has to be discharged before removal to prevent one from being shocked. Discharge is easy, screwdriver between the terminals.

Technical answer to your question:
A capacitor in a home air-conditioning system stores a small electrical charge and releases it when the system’s motors need help starting or continuing to run efficiently.

Most outdoor AC units use a dual-run capacitor, which serves two components:

• Compressor: helps start and run the compressor that circulates refrigerant.
• Condenser fan motor: helps start and keep the outdoor fan spinning.

The capacitor creates the electrical phase shift and torque needed by these motors. It is somewhat like a temporary electrical “push,” especially during startup.

 

[Rand]

you should replace the contactor too but keep the old one for emergency spare.
I replaced mine and the replacement lasted a couple days.


I also replaced the CAP, and the fan motor. I had it apart about 3x forget the exact order of problems.

but a fan motor repair by hvac guy was $1000 quote. My first 2 motors were DOA/damaged.
I think I am about 250 into it with a motor, 2 contactors and 2 caps (one for spare)

Not that hard. dont shock yourself. Take about 10 before photos for wiring.
go slow and be careful.

Hvac is so fun /sarcasm.
First motor was used with burnt wiring.

second motor was clanking-- dropped?


Third motor had a small dent worked ok.

@GON
What size filters are they? I typically pay around $3 per 16x25x1 filter merv 8 equivalent.

some of the 4" thick filters get pricey.

 

[alarmguy]

@GON

I always buy filters online.
These look pretty good. I actually have 10 of them ordered ~ combination of two sizes.
https://www.amazon.com/dp/B0F3CDHC95?ref_=ppx_hzod_title_mob_b_fed_asin_title_0_0

You got your air-conditioning working!
Yes, very satisfying!
If it’s an older unit in the future, also pick up a contactor if it looks well used and a little burnt up

 

[GON]

you should replace the contactor too but keep the old one for emergency spare.
I replaced mine and the replacement lasted a couple days.


I also replaced the CAP, and the fan motor. I had it apart about 3x forget the exact order of problems.

but a fan motor repair by hvac guy was $1000 quote. My first 2 motors were DOA/damaged.
I think I am about 250 into it with a motor, 2 contactors and 2 caps (one for spare)

Not that hard. dont shock yourself. Take about 10 before photos for wiring.
go slow and be careful.

Hvac is so fun /sarcasm.
First motor was used with burnt wiring.

second motor was clanking-- dropped?


Third motor had a small dent worked ok.

@GON

What size filters are they? I typically pay around $3 per 16x25x1 filter merv 8 equivalent.

some of the 4" thick filters get pricey.

The filters are the normal size and readily available types:

 

[DCDG]

As my wife would say, you get a notch in the husband card. Good job!

What does the capacitor do exactly? Thx.

for single phase motors its the extra kick in pants aka torque that the motors need to get going. they store a charge of energy. that's why it is good practice to short across the terminals with an insulated handled tool to discharge them when replacing. then there's some capacitors that have a bleed resistor.

 

[Nukeman7]

Nice job on the A/C repairs in an emergent situation. I suggest stocking up on a spare capacitor and contactor for each outside unit along with a capacitor for the inside air handler fan motor(s). If both units use identical caps and contactors, you only need one spare of each on hand since simultaneous failure is very improbable. Amazon has numerous brands (mostly from China), but I recommend the U.S. made AmRad caps.

 

[Cujet]

Good job!!

Also of note, if the condenser fan quits (outdoor unit), a shop fan can be placed on top and sealed with wet towels. This will pull air through the unit and get ya through a weekend emergency.

More than a bit absurd, as something 1/3rd the size will work just fine. But you get the idea.

 

[ArrestMeRedZ]

Might I suggest you write down the capacitor specs, or store them in your phone? I replaced mine when it failed. When it failed the second time years later, it wiped out the label and I couldn't find the values anywhere.

 

[jkasch]

I keep a spare on hand, but decided to have an HVAC company that I really like do their $99 “tune up” on my 13 year old Bryant even though it seemed to be working fine. He did all the promised tests/cleaning and told me the capacitor had drifted out of spec causing the fan to run at an incorrect speed. I handed my spare to him and he installed it without any additional charge. Good HVAC companies are a great find.

 

[Hall]

Where are the HD capacitors made ? I see the US flag on them but.... never mind, I see the one that's turned to the side that says they're made in the US.

 

[walterjay]

At least Home Depot didn't tell you that you needed to replace the unit.....

 

[dishdude]

This was my saga a few years ago.

D

Thread 'Just fixed my A/C!'

Sep 6, 2023

I have to gloat and you're the only crowd that will understand. I was sitting here about an hour and a half ago and noticed it getting warm in the house. Went to check on the vents and they were blowing warm! Go outside and the outdoor unit isn't running. Did some quick checks with my multimeter to make sure it was getting juice, felt the condenser fan and it was very hot. The fan spun freely when I tried spinning it with a paint stick, but since it was getting late I did a quick search for a capacitor and fan, no fan available tonight but the local Ace had the cap! Decided to...

• dishdude
• Replies: 63
• Forum: General and Off Topic

• 
• 
•