Timely topic.. my unit went kaput (So I thought) Sunday.. turned it on and it sounded like a stuck pig squealing! I thought the motor in the compressor was shot, so we turned it off and pretty much suffered all day...
Had a guy come out yesterday... I turned it on, and of course, the motor just purred!! It does run hot tho.

So he hooks up his gauges and about falls over! They were running about 200-250 on one gauge and about 375-400 on the other. That's what the guy said anyway. He let some freon out until the gauges read like Indy's post above..He said he's surprised the unit hasn't blown out by now. Too much pressure bad for compressor?! I left it on for the rest of the afternoon but it was too late to do any good. The house never cooled below 85.
He didn't try and sell me another unit, but I am under the recommended tonnage. The unit I have is 3.5 tons and the house is about 2000 s/f. He recommended a 5 ton unit... What is the correct tonnage for a house that size?

So just now (after starting to read this topic) I did a test on the start-up, and sure enough, she squeals for about 10-15 seconds, and as I'm running to turn it off, it stopped squealing and sounded normal! So now I'm really baffled. Why would it squeal? Motor bearing?

Replacement is in the plans for next year, but he said to get it before the end of the year as the EPA is requiring the change to puron in 01/09 and the units will be more expensive. If it'll last just a few more weeks......

All units have to go to 134a or better next year. That shouldn't have a big impact on cost though. the big cost impact was 2 years ago when the mandate from 10SEER to 13 SEER went through.

There are some state EPA's that say when a leak is evident, you must at least identify it. If the leak is in a coil, it is nearly impossible to fix. Schrader valves/caps are always a good place to find leaks. Many of the caps do not have o-rings as they are not there to stop leaks, just prevent dirt. But the schraders do wear out so having the o-rings is a benefit.

As for sizing an A/C unit, there is a lot that goes into it above square footage. But 3.5 tons for 2000 sqft should be adequate unless you have a lot of sun exposure, windows, poor insulation, etc.

WaterMutt, our house is 2 story, with a pretty big attic. I know it's not ventilated adequately, as the temp in there gets absolutely unbearable, even in the winter sunshine, but there is about 3 inches of blown-in insulation. And yes, we have alot of south-westerly facing windows.

When it started getting warm today, I went to turn on the A/C.. I heard the motor running, but couldn't hear the fan turning the air. When I went out to look at it, the motor was on, but the fan was turning very slowly, gathering speed with each revolution, until it suddenly went to full speed... That, to me, would indicate a bearing about to fail. Any suggestions? Is that a repairable item that's worth the cost?

rule of thumb on residential units is about 600sq ft per ton.


the condenser fan motor may be getting ready to fail, or the bearing is failing. either way you dont have a whole lot of time left

what kind of refrigerant is that unit??? those kinds of pressures would be "OK" if its a 410a but if its R-22, at those pressures there might be significant damage caused by slugging of the compressor..

And it's not cooling good either. It's only 90 today, and it's 82 in the house, and the thermostat has been at 74 all day.... Normally, it has to be above 100 outside for it to get this hot inside

How can I tell? The unit is at least 5+ years old, as it's the one that was here when we bought. There was no freon added, that I am aware of, 3 years ago when we had a condensation leak.

The ID plate (not sure if that's what it's called, but it's the metal info tag) is on the back of the unit and hard to get to. Should there be some way to tell on the plate what type of refrigerant is used?

+1.

Indy, how did you find the leak?

I missed all the new posts on this yesterday.

Brady - yeah, I'm pretty well aware of my limitations. I know quite a lot about my systems, but would be lost on something much different.

Nu2 - sounds like a condensor fan motor or bearing going bad - which should be a cheap fix if it's the bearing, but you may end up having to buy a new motor. Note; that fan has nothing to do with the refrigerant or the compressor - it simply blows air over the coils to condense the Refrigerant. Now, its very curious that your pressures would be that high - especially since it wasn't recently charged - and now it's not cooling any more. I personally question whether the guy was reading his gauges correctly and maybe it was charged correctly to begin with and now it's undercharged - since the source of the initial call was the squealing and that has nothing to do with the refrigerant charge. I'd bet the unit is a gibson or a Janitrol brand - they do tend to make a lot of noise. Call somebody else out to check the charge - since the first guy didn't diagnose the fan squeal correctly. 3.5 tons sounds right for 2000 sqft. If it's done OK in the past, it would waste energy to buy a bigger one. There's no reason that a unit shouldn't last way more than 5 years. I'd say 10-15 minimum.

As far as going to the new refrigerants - well, they aren't as good at refrigeration, so the unit sizing, therefore the cost will go up, to get the same amount of cooling. My opinion is the jump to 13 seer was mostly just an excuse for a price hike for everybody in the chain - the actual equipment changes were relatively minor - usually bigger capacity evaporators and inclusion of TXV's.

Finally, about my leak. Well, I wish it would have been more scientific, but it wasn't. The service guy came out and filled it several times over the course of about three years, telling me how much greater a new one would be each time. I had bought the "service Plan", however, so I got a discount on the service and didn't worry about it much.

I called my BIL out and he looked at it and filled it and said their must be a leak. He told me to look for oil/dirt spots all around the condensor and compressor. Then I bought a couple books on AC and started reading, bought some gauges, and got the license and some R-22. I filled it myself a couple times and noticed it leaked down really fast after I did it one time, when I lost one of the caps, and put a plastic one (from the R-22 container) on it. At this point, I had thoroughly looked over everything and thought if it was a leak it must be in the evaporator. So I bought a leak detector and the only place it got any kind of reading was around the uncapped schrader valves. That's when I got the idea it must be the lack of O-rings in the caps - which solved the problem, so far.

My units are now 17 years old. They work perfectly, and they get a real workout in the summer. At this point, I also determined that I have no desire to have new ones until these won't run anymore. If a compressor goes I'll probably replace it alone rather than the whole system.

I learned two things through the process. 1. The "service plan" that I bought was just an excuse for the service company to try to sell me stuff. They didn't do the proper service, which I learned to do myself, and they had no incentive to fix anything. 2. The whole industry is geared toward replacement rather than fix. I'm convinced that most residential guys just don't know how to do repairs. They want to replace the whole system if the compressor goes out. That's like junking your perfectly good car if the transmission goes bad - sure it costs money to fix, but not as much as a whole car.

Many times due to the age of the unit, labor for compressor replacement, it is better to replace the whole condensing unit. I've priced quite a few jobs, and sold many condensing units based on a $300 difference between the two.

There is a pretty big shortage in qualified and experienced HVAC techs. Many are just gas-and-go guys with little understanding of electrical components and really how the units work.

brady and Indy.... thanks for your info..
I checked the mfg tag and the date is 7/91. Of course, this does not tell the date it went into service, but the unit is now 17 years old from mfg date. And it is an R-22 type refrigerant.
The service guy told me that a slow spinning fan will not pull enough heat off the condenser, thereby not allowing the coolant to perform to maximum efficiency. What do I know! Sounds plausible.

In calling around this morning to see about a fan motor swap, I talked to a guy that said it could be the capacitor going, which would be a real cheap fix, and something I could do. Even swapping the motor sounds like something I'm capable of doing. I've been quoted from $285 to $681 for something that doesn't appear too tough! Getting the motor might be the tough part, as I'm not sure where to start there....

From the description, my first thought was bad capacitor. See if the motor itself has a data plate on it, and try to find a cap or a motor that matches those specs and shaft dimensions.

I hear of people all the time who are told they need a new AC because their condenser fan motor went out. That always seemed like a crock to me. Commercial building owners certainly don't replace their entire AC systems every time a component fails. Not really apples to apples, but the idea is the same IMO.

$300 is a fair difference - then it's just a matter of whether the customer has the money or not. I'm sure the entire condensing unit is a much easier and probably more reliable install - but the guy who has the skill to take on the compressor only is the guy I want working on mine.

I think the "gas and go" guys were the ones that forced me to figure it out myself, so they did me a favor.

This is true. But if the last guy let out a bunch of the refrigerant and shouldn't have, it still won't work.


Even $285 sounds like a lot for a motor - although I will admit I haven't bought one. I've bought HVAC blower motors from Grainger before at about $100.

Should be easy to tell if it's a motor or bearing. Cut the electrical, then take the top off the condensing unit - about 8 screws - the motor and fan are usually attached to the bottom side - If it has a bad bearing you should be able to tell by spinning it and/or wiggling the shaft.

Capacitor/electrical is one thing I would leave to a repairman, unless you know how to work on electrical stuff.

I would expect these motors to cost quite a bit more than the typical household or tool motor, since they have to be built to withstand and run in very wet environments and extreme temperature differences. But how anyone could charge $200-300 for installation labor, I don't understand.

For the capacitor, pull the disconnect, discharge the cap by placing a screw driver across it. Pull the wires, typically two brown ones, but now you need a meter that measure farads. The cap will be marked on what it should read, I think you need to be within 15%.
That's how I used to do it, becareful doing it yourself.
I've found that if the cap is bad, the motor will be joining it shortly. And if you replace the motor, spend the $5 and get a new cap.
Grainger can be pricey. Try to find your local HVAC parts house and see if they'll sell to you, many will, especially when the part doesn't touch refrigerant. Then again, I haven't done this in over 8 years.

wear gloves and shut all power off to the unit, then discharge the cap. The capacitor holds a charge so be careful when you handle it. Also make sure that the screwdriver or pliers is insulated..sometimes sparky hurts!!
Mutt's right about the motor going bad if the cap goes. you can get a cap fairly cheap but the motors (depending on the make/model/year) might be a bit more spendy - ESPECIALLY at Grainger!!! it might be that the motor is ok, just the cap but to often then not the motor is going to fail eventually.

Nu2u: that guy had to be reading the pressures wrong! probably using the wrong set of guages or wrong manifold, there is no way that the high and low side of a unit of that size could perform AT ALL with high pressures like that.
If he let some gas out, you are not going to get your super heats correct and your unit will probably - if not already will be smoked by either slugging or will start to ice up...