Chances are that you need a new capacitor for the compressor. You could easily draw 50 amps, if the cap is bad. I would expect a bad compressor to blow the circuit breaker instead of trying to start. The buzz sound is the compressor trying to start.

High/low pressure switches sound like a great idea, until they fail. The cost to replace is expensive, since you have to cut the line, braze in a new switch, then re-charge the system. It is easier to eliminate the switch. Many times the installation can ruin the switch from too much heat. Kinda dumb in my opinion.

The switch had a purpose and because it was ignored, may have caused the compressor failure. I have rarely had any trouble with psi switches and if one goes bad, sometimes one can be installed using a tee in the line to avoid opening the system.
If the compressor "lock rotor amps" are being met, the compressor is bad. If your lucky a new capacitor may get it running, but I'm sure the tech did that.
The cause for the control being jumped should be looked at. It's possible the outdoor motor may have problems. Or a metering device is not working properly.

He didn't try a new capacitor. When I spoke to him on the phone before he stopped by, the first words out of his mouth were "sounds like a bad compressor." That is one of the reasons I had some doubts.

Bikey, probably from what you explained to the 2nd tech his first instinct was to suspect a seized compressor. Things like that happen when you work at something long enough. Its called "experience"! So here's a tech who listens to what the customer is trying to explain. Thats usually a sigh of a very good technician. And for that, you have your doubts about him before he even comes to your house! So if some tech in this forum tells you the same thing from your description you're gonna be skeptical of him to I suppose.

Bob - thanks for the info. This kid diagnosed the "problem" in less than five minutes, then told me mine was the third system he had seen today (at 1130 AM) that needed a new compressor. I had doubts after he showed me the specs showing the current draw when the system is running and said the higher start amps meant there is a problem. I'll take your advice and replace the capacitor.

Your logic on the switch sounds reasonable. The other unit is the same way, so it looks like that is the way the installer routinely does them.

It has gotten almost impossible to find a good HVAC guy around here. The company that installed it really hates to do repairs. They are small and I think they make their money on new systems. They only have one repair guy. I'm more than willing to pay good money for good work, but the DC area market is so tight that it looks like there are a lot more hacks than experienced professionals.

Last year, on a technical HVAC forum only for techs? We discussed dry capacitors vs older oil filled capacitors. The newer caps are cheaper. They also fail much quicker. I am replacing many bad caps that test ok, but they fail under load. No manufacturer can explain. Just junk, again sold as quality.

Bikey,

Approximately 85% of the compressor change-outs on residential units are not needed. Technicians often time do not do a detailed job at diagnosis.

On Memorial Day, I went on a service call. It was a less that one year old Lennox A/C two ton unit. The compressor was trying to start. And, it was drawing "lock rotor amps". I checked out the compressor, by the book, and it checked out as good. Though it did not start until I installed a "hard start kit". The final results? It was very noisy and very bad.

Phillip

Thanks Phillip. I don't think this tech could be called detailed at all. Five minutes seems too quick to really check out a system. He was probably 25 years old and I doubt he has much experience. Probably the reason he was stuck working the holiday weekend. The capacitor is supposed to be here friday, so I will give that a try first. If it fixes it I may buy another one just to have a spare around.

One person I talked to said the length of the run between the compressor and the air handler could make that unit more troublesome. It is probably 45' - 50' or so. On the surface it sounds logical, but I don't know. If so, is there anything that can be done to help? This unit has had an issue every year. The one beside it just hums along and never gives me a problem (knock wood).

Bikey-I am swelteringly awaiting in Falls Church, the 3rd estimator for a new compressor/air handler because of "freon "
leaks in the system. So far I've heard $5,800 & $6,600. Have you learned anything that might help me - Thanks - Sallie

Sallie,

I ordered a capacitor and plan to install it on Monday when I am at the house. I've had lousy luck with HVAC contractors around here. The worst was Vernon... I called them about adding a second zone to the house and they actually sent a guy wearing a silly looking white lab coat who called himself "Dr AC." He knew absolutely nothing.

If I don't fix the current problem with the capacitor I am going to check Angies List and see if I can find someone there.

Bikey:

Because Angie's list charges a commission for referrals, and because Angie's list has a good reputation, some of its members in all the trades tend to charge much more when they get referred to a consumer by Angie's list.

Angie's list can not do anything about what the contractor charges customers because that might be seen as "price fixing" by government regulators.

The good thing is you can always request mediation after the fact but to bolster your side you would have to get examples of the contractor charging their other customers less for the same work than work referred to them by Angie's list.

Fairyprincess

Bikey - glad you started this stream, it's certainly given me added info. Just after I posted, the 3rd estimator from Furr arrived saying I needed a second opinion on the leaks to discover exactly where they originate. Do let us know how the new capcitor works. Sallie

Furr is the company one of my best friends uses for her plumbing work. She had very good luck with them until this spring. They sent a plumber in who was not very thorough. She had a leak that he didn't trace properly. He fixed the first leak he found then turned everything on and left. She woke up with a hole in the basement ceiling and water standing in the floor. It took 2 or 3 visits from them to fix it.

Bikey - thanks for the comments on Furr- Sallie

Fairyprincess - I don't think companies pay anything for Angies List. They make their money from subscribers. The way the list works there is no way to know if a customer called because of Angies List. I think Service Magic may use the business model you described. I find their info to be far more supportive of the companies and not particularly useful.

It looks like tech number 2 was right. I tried replacing the capacitor and it would not start. Added a hard start kit and it started right away, but sounds like cats fighting. The really irritating thing is they are telling me the original installer put in a two year old unit and the warranty on the compressor started when it was manufactured, not when it was installed.

Most residential and light commercial compressors have a minimum five year warranty. The equipment's warranty generally begin at installation, or when the home is sold and closed on. If date of first ownership, or start-up can not be shown, the warranty will start 90 days after date of manufacture of the equipment. The manufactured date of the compressor is not an issue.

Thanks remodeler. I have the invoice from the original installer so I can prove the date when it was installed.

Is a three year old unit failing common? Is it likely that there is a problem that is causing it to fail?

Update on this issue. I had another tech look at the system today. This one was recommended by the Ducane distributor. Turns out the tech who said it was the compressor (Mr. experience) had his head up his butt. The compressor is bad, but there is an underlying problem what caused it to go. One of the lines from the condensor had snapped. The guy who came today asked if the 1st guy had even looked at it. The gap between the two ends of the broken line was about 1/2", so it was very noticeable. He is ordering the parts to fix everything. It will be covered under the parts warranty. The Ducane distributor was very helpful.

Would there not be a low pressure switch to cut the compressor if all the charge vented from the condensor line? Maybe the high pressure switch that was a bypassed was actually a combination high/low switch. This would allow the compressor to run without a charge. Spinning it dry for too long will kill it.

Absolutely! A low psi switch would have saved the expensive compressor.