Q. I'm living in Shenzhen, People's Republic of China. I live on the 9th floor of our 34 floor apartment building, and just had to have our external air conditioning serviced. I was alarmed and amazed as our air conditioning technician tied a rope around himself, and then went out the window to the external air conditioning unit to give it a dose of freon (as I held the rope!). My gf asked, what do they do in the USA?

A. In the USA buildings have central Air-Conditioning and the equipment is usually located on the roof of the building.

Q. Please anyone know the estimate? I have no idea and interested in getting central air conditioning system for my home...tks!

A. Trane and Carrier=You pay for advertising. I just bought a 3 ton Goodman for $1200 installed, outside unit only. Entire central air system with inside ducts, etc.: who knows.

Q. The air conditioning in our house went out over night & last time it happened (about a month ago) we changed the filter & it worked again just fine. So, we changed the air filter agian, but this time no luck. it's not sucking in air where the filters go, any suggustions -- besides calling someone over to repair?

A. Either your fan/blower isn't working, or for some reason it isn't trying to run. Check breakers, and fuses. thermostat setting.

Q. Unit is only 5 yrs. old, not sure if I'm quoting right I had about 5lbs. of pressure they took it up to 60-70 I believe.

A. Average range $175- $250. unless there is a leak on the line. than it's more.

Q. The recent problem seems to be related to the outdoor cooling fan. The air conditioning system seems to be working properly, but there is a loss of cooling of the air coming from the indoor air conditioning vents. I inspected the outside unit, and yesterday the cooling fan was stopped with a humming/grinding sound. The capacitor looked good (no bulging), but I'm not an electrician and I have no way (or the knowledge) to test voltages and amperages and such. Anyway, I blew on some dust/dirt/cobwebs around some of the wires, and started the system back on and the fan moved at normal speed and the system worked and cooler air came out. However, today, the indoor temperature wasn't maintained and I went outside and the cooling fan was running much slower (but it was running). After I turned off the system, I felt the metal cover of the outside unit, and it was very hot, and it seemed that the source of the heat came from directly above the cooling fan motor. Please contact me!

A. Replace your outdoor fan and while your at it replace the capacitor and everything will be fine. But turn your unit off untill you get it fixed or you'll be changing a compressor or buying a new unit.

Q. I just got the ducts in my house cleaned out to get rid of pet dander and help me breathe better. The air conditioning is running great now and seems cleaner to breathe in. The only problem is that there is a loud humming noise coming from the big vent on the wall. It only comes from this big vent, and does not resonate from any of the vents on the ground. The big vent is not the original big vent; my contractor replaced it after the ducts were cleaned because the old big vent was dirty. My contractor says the noise is a result of the air running so openly now, but I'm having a hard time buying that. I think it is the replacement vent vibrating when the air pushes through it. Any thoughts? I'm pretty sure he threw away the old big vent.

A. Call him back and tell him your not satisfied.Lining the duct with duct insulation should help.I think your right about the vibration.

Q. Just looking for ideas to check for when a service technician comes out to look at my air conditioning. I know these guys are very busy this time of year and just want to be careful that I am not being taken for a ride as they tell me a whole lot of this that may not even be the problem so they could just charge more. Basically, my problem is if you feel the skinny high pressure line from my condenser unit outside it is colder than the insulated line and I don't think that is the way it should be. My neighbors high pressure line is hot, why is mine not? The cooling inside is doing okay but it feels as if it should be cooler. Also any advise on what else I could check for myself before I call the service tech would be greatly appreciated.

A. Its hard to say what your system is doing unless we had system pressures, superheat and subcooling readings. Does the air off the top of the condensor feel warm? it should be at least warm. Now your liquid line( skinny line) shouldnt be hot but it shouldnt be cold either, the heat is pulled from the refrigerant at the condensor and is cooled down back to a liquid state from a gas state, the temperature of the liquid will drop as it makes its way back to the indoor coil. You can check your temps in the house, you should have about an 18-22 degree split between the air returning to your unit and the supply air coming from the air registers.

Q. I went to school for hvac got out and started at a company but they started me out as an installer and im not sure if thats the start i wanted to this career i mean if i need it ill do it but what else can i do apartment maintanence or look for a helper position or should i just stay and try to become a lead install and how long would it take to become a service tech from an install?

A. School can teach you the fundamentals, but you NEED hands on experience to learn the things they don't teach you, the tricks of the trade if you will. Besides, isn't installing an AC part of being a tech? There are very few occupations where you can just take what you learned in school and jump into the real world. Most occupations have some form of apprenticeship. Did they teach you how to deal with customers that overlook your shoulder? Code violations you find? Dealing with building inspectors? Getting paid? Dealing with suppliers? Writing up estimates? Did they teach you EVERY cause of every problem in an AC? Have you been taught on every make and model there is, old and new? (I had to read and interpret the wiring diagram on my air handler to the ac tech working on my system that couldn't figure it out). If you're as independent as you think you are, the company will soon recognize your talents, and let you go on to other responsibilities. And just remember, with the economy the way it is, there are plenty of unemployed craftsmen that would be willing to start at the bottom again. Be humbled.