Just need some info/guidance on "maintenance" versus upgrades. Once of our AC units quit last night and I had the company come out today to diagnose/repair. They are just under 5 years old and we are the original owners.

I design commercial HVAC system, but I may be able to help. 5 years is not very old. Most systems should have a useful life of 15-20 years. Have it diagnosed. If it's simply a leak, get it fixed and recharge. If the compressor is shot, you'll need to weigh the cost of repair vs a new condensing unit. New ones will likely be more efficient and save you a few bucks on the electric bill. Unless you existing one is a low efficiency unit, less than 12 SEER and the new one is more than 19 SEER, the new one will not likely pay for itself in reduced energy costs. Even if you can drastically increase efficiency, it will likely take most of the life of the unit to pay back. Of course this is totally dependant on your electric rates (now and future). Some electric companies wil offer rebates if you upgrade to a high enough efficiency or install a heat pump. You might want to scan the local companies web site before making a final decision.

Hopefully, that helped some, I'm not really sure what your questions are.

The tech said we needed a start capacitor, which was not installed by the original AC company at the time of building. The tech said the original companies have been doing that to reduce costs on their end. He installed another run capacitor because the one installed in May was bulging. He said the run capacitor should normally last 4-6 years.

The electric bill is one of those "managed plans" where you work up a debt, then pay it off in the off-season. Our average isn't bad so I'm not too concerned about that; I'm just frustrated that every time the AC company comes out I end up spending money. I contacted some neighbors and most have not touched their units, and they are 2 years older. The ones who have had maintenance done have not had as much as we have. We've had the run capacitors replaced on both units before as well.

I have to say, my home units have never needed that. I had a leak once, but other than that they have been basically maintenance free. What brand do you have? I've found the Trane units to be very good. It's possble that you have some very dirty power in your area. If these capacitors are dying, maybe they are under sized?

Sounds like you need something the old school guys called a "hard start" kit (which is just a start capacitor). You may have another problem and this is a band-aid. But given the age of the system, I would install the start capacitor and see where it goes from there. You should get AT LEAST five more years out of it, which makes sense to repair rather than replace.

For some reason your electical system may be overheating. Could be a lot of things. Low voltage, undersized conductors, bad connection(s), worn compressor pulling too many amps. The tech should have checked all this stuff, but sometimes they just slap on the capactor and hit the road. If you trust your AC guy, pay him an extra hour of time to recheck all your connections and your input voltage all the way to the panel since this seems to be reoccurring. Also make sure the compressor relay isnt arcing.

Good luck. You will find (like everything else) that AC systems have increased dramatically in price over the past couple years....you'll want to avoid that eventuality.

Bock

Units are from Carrier -small one is model 38CMC024310, 5.0 lbs R-22 refrigerant; large one is model 38CMC042300, 6.75 lbs R-22 refrigerant.

The tech essentially just replaced the capacitor; no other system review was completed. I was surprised that they were going to charge for the repair, when the previous run capacitor quit so quickly. After I mentioned that, the tech called his supervisor, and they agreed to warranty the capacitor ($200ish) and only charge the labor to change it out. I agreed and the tech did the work, then wrote the ticket up and didn't charge for the labor. Something very fishy about that, even though it was to my good.

The temperatures this summer (so far) have not been that bad, compared to last year. Other AZ people may agree/disagree, and I don't have a problem with playing golf in 110-plus weather. The tech did say that the location of my units could be contributing to the problem due to reflective heat, as they sit on the east side of the house, in a narrow spot in between the house and the concrete wall, and surrounded by 3/4" rock on the ground.

Yeah, nothing lasts forever, I'm just trying to figure out if I'm getting ripped. Adding the start capacitor is probably the best thing to do.

http://dnr.louisiana.gov/sec/execdiv/techa...ep/hvac/d/d.htm

http://highperformancehvac.com/capacitors.html

http://www.arnoldservice.com/air_conditioning_parts.htm

http://www.action-electronics.com/capac.htm - Most from $2 to $10.

Most larger single phase electric motors have start/run capacitors, and they're usually an order of magnitude cheaper than $200, and probably takes 2 minutes to replace once you get the cover off (make sure you discharge it first! High Voltage!). My little drill press with 1/2 hp motor has one as well...

A.

I'll repeat Andris' caution - treat a big capacitor like a high voltage battery. Discharge thru a power resistor to avoid arcing.

Placement of the unit can effect how well it rejects heat reducing (or improving) the effective capacity of the unit, but it should not have any effect on the motor, compressor etc.

Yep.

We had a new Trane unit installed when we remodeled our house in Buckeye (APS power) back in 2002. In less than a year the controller board fried. Chas Roberts (the installers) sent several techs out to look at the unit because they hadn't experienced this particular failure before in such a short period of time. They repaired it and installed a surge protector... no charge. Two years later during a monsoon storm, the surge protector fried (I guess it did its job). Some of the same techs came out and after some more head shaking and a call to APS... they replaced the surge protector, again free of charge. A month or so later, APS replaced the transformer across the street from our house. We haven't had another problem since then...

Don't think we have dirty power, otherwise my neighbors would be having similar issues, right?

I watched him replace the run capacitor - he spent more time repacking the capacitor so the cover panel would fit than actually swapping the capacitors...

I also remember when they added the start capacitor to the other unit - there was some difficulty in getting the cover back on. Took quite a while for the tech to do that, because that was the smaller unit. Now, what he attached the wires to I have no idea. Initial thought is to take the cover off of the unit with the start capacitor and just mimic that setup on the unit that needs the start capacitor.

Every time they worked on the units they pulled the fuses but I never saw them discharge anything.