Home AC troubleshooting

[john70t]

Thank you for the correction. My mistake. That was a completely boneheaded post without even a cursory search. Trying to help but doing the opposite.

[billybek]

If the filter looked that nasty, then you can be sure the indoor coil is plugged with shmeg as well.
You may have to do a little surgery to get at it to clean it.
If the compressor is baked, I would consider getting a new R-22 condensing unit. They are still available, only now they come without refrigerant. Yours is a heat pump application so the reversing valve will add a few bucks to the deal.
If the system has been installed well, you shouldn't have leaks. Ever. On a very old condensing unit, you will eventually end up with tube sheet leaks from vibration. One of the reasons I was suggesting new.
Hopefully it will start. Will usually have a capacitor start and a run capacitor (sometimes both in the same shell) and a potential relay to take the start cap out after the amperage drops off.

[wdfifteen]

Originally Posted by red-beard

You people turn off your AC? Ever?

Ha! My system hasn't been on for heat or cool since February.

[Geoz1]

Originally Posted by john70t

Renting or a new home purchase?
That's an older unit, and if not cooling now, the damage may have already been done. They leak regardless especially if not run several times a year. The circulated oil conditions the seals and prevents leaks.
Not sure about the R-12 replacement costs/proceedures. All new ones use R-134A.

Look at the SEER rating label. Each number higher equals a significant improvement in efficiency. 20% or more i think. Depending on the zone and usage, replacement now will save a lot of money and discomfort.

There should be two tubes running into the house to the furnace, one hot straight from the compressor and one cooler/ambient return.

You sir, have no clue what you are commenting on.

[BK911]

So last night I finally got back to messing with the AC. Put it all back together and fired it up.
Nothing!! Just some clicking noise I think was coming from near the capacitor, but I didnt stick my head too close.
Compressor ohm'd out so electrically it is fine.
Inside coil was surprisingly clean. I expected it to be FILTHY.
Capacitor looks ok, just old. Usually they bubble up and / or leak when they go bad.
I will buy a couple of spares anyway to keep on the shelf (because I am a hoarder!)
Hopefully tonight I can replace the capacitor and see what happens.

Yup, no home inspection. Except my walk through.
This was a short sale so I bought "as-is".
I knew the AC did not blow cold but it was not stopping me from buying this house.

[BK911]

Originally Posted by rick-l

Well? Did it run?

Did you stick an ohm meter on it? S-C R-C R-S (sum) R-Case

I ohm'd s-c, c-r and s-r. I did not ohm r-case. What should I expect?

[billybek]

Take the model number of the compressor and find out what electrics (potential relay and capacitors) are matched with it. You may still get lucky and have the motor start.
New 400 series refrigerant condensing units need to be matched to the coil so it is a high dollar change out. Installing a R22 condensing unit will make good use of the equipment already at the house.
Is the house a flipper or a keeper?

[red-beard]

R-22 units are not expensive. My R-22 units needed replacing last year. I purchased a 4 ton and a 3 ton unit for $1379 and $1159 respectively, including free shipping. Installation was about $300 for each unit. I hired an apartment complex super who freelances on the side. These are RHEEM units. You can get Goodman units for 20% less.

[rick-l]

Originally Posted by BK911

I ohm'd s-c, c-r and s-r. I did not ohm r-case. What should I expect?

S-C should probably be about 5 ohms, R-C should be 2 or 3 and S-R should be the sum of those two. Anything to case should be open.

You can also stick your meter on the capacitor as a gross check. Discharge it and it should start out low ohms and go to out of range.


EDT: I have never seen one of those scroll compressors however.

[rick-l]

Well ???????????

Did you see sparks and smoke?

[BK911]

No sparks, no smoke, but no cold air!!

Put in the new capacitor, turned on the air, and only heard clicking from the contactor and an intermittant loud hum/buzz from around the compressor.
Measured amps on the incoming power and got >100 amps right before the breaker tripped.

So locked compressor?

[Zeke]

Originally Posted by BK911

No sparks, no smoke, but no cold air!!

Put in the new capacitor, turned on the air, and only heard clicking from the contactor and an intermittant loud hum/buzz from around the compressor.
Measured amps on the incoming power and got >100 amps right before the breaker tripped.

So locked compressor?

That was my thought from the beginning. I think you proved it. It won't get any better.

Last Saturday I was out in my yard when the neighbor's condenser came on. It ran for a few minutes and then I heard a couple of loud rattles, it stopped, started for half a second and wham! I kept looking over the fence for the smoke, but all was well except for the pump.

I don't think I've ever actually witnessed a catastrophic failure as I did right then.

[dhoward]

Make sure you're getting 220 to the compressor and the terminals haven't burnt. I had the same symptoms and one of the termials on the compressor from the contactor had burnt through.

[red-beard]

You can buy a replacement compressor only. But for only $200 more you can buy a whole new condensor.

[john70t]

Also: In the noble pursuit of fixing the details, consider replacing the whole unit with a much more efficient one.
Once moisture and particles gets into an older sealed system.....

Calculate usage costs over 5-20 years, with personal time, with additional materials, with comfort.

[red-beard]

John, I agree that he should install the most efficient unit which makes the most sense.

I looked into replacing my AC unit with a super efficient 24 SEER unit. The problem was it was going to cost $25,000 to do this. Instead I replaced my failing units with 2 x 13 SEE units.

Installed cost of the 13 SEER units: 3K vs 25K. So, I would have to save $22K in operating costs!

My average Elec bill is $250/mth, of which $125 is cooling. So I have a $1500 per year cooling bill. A 24 SEER would save me $700 per year.

If I had moved to 410a, I would have had to replaced the evaporator inside as well as the condensor. So, even with a two 14 SEER systems I would have paid $10K for install. I think I could have had 15 or 16 SEER systems for about the same price installed.

$7K in extra cost vs. for maybe $300 in savings per year.

Oh, and all of these costs are for operation in Houston. Elsewhere the cost savings will be much less.

[Rick Lee]

I've gotten a few quotes to replace my 16 yr. old a/c, which is still working very well. $7k seems to be the avg. cost to upgrade to the new 410 unit. But my electricity costs are about $2500 per year, maybe $1400 of that for cooling. It will have to be done eventually. But the savings ain't there and cost to go solar wouldn't save me a dime for over 10 yrs. even if it meant never having to pay for electricity again.

[red-beard]

Rick, I should go into that business. The parts for an 18 SEER system are about 4K-5K, depending on options (manufacturer, etc). For a 13 SEER system the parts are $1.8K-2.3K. For $7K, I expect they are putting in a 13/15 SEER unit. Install should be 2 people for a full day. Freon ~$100. Gross profit on $7K system would be about 50%!

[BK911]

Originally Posted by dhoward

Make sure you're getting 220 to the compressor and the terminals haven't burnt. I had the same symptoms and one of the termials on the compressor from the contactor had burnt through.

Would the imbalance trip the breaker? I only got amp readings on one leg, the other read 0.

And no catastrophic failure, but I was standing behind a metal door just in case!

Not sure what I would do if the compressor is bad.
New compressor?
Ground source heat pump?
Mini-split heat pump system? I like these because you cool the room you are in, not the whole house. Sorta like improved window shakers. Air-conditioning Systems - Products - Small Multi Systems

Fortunately the garage is cooled off another unit, so this isnt a huge priority.

[Zeke]

When it comes to adding better A/C to my house beyond the window units in the bedrooms, it will definitely be a split system. NO ducting means a lot.