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.

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Q. We live in an old 1950's house and currently have central heating, which my husband installed in our home a few years ago. Is it possible to add air conditioning, as well. Can anyone help out with advice or how it would work and what the cost would be? Real answers, please...no trolls!

A. You want to start with what you have that is very familiar to you but you haven't described it enough. Is it a forced hot air system with duct work and is the duct work insulated? If this is the case then the process is to install an "A" coil above the furnace and below the plenum that distributes air to the various ducts. This is connected to a condensate drain, and two refrigeration lines that are also insulated. The refrigeration lines connect to an outside unit called a condenser. The condenser has to have electrical power attached to it. The refrigeration lines must be vacuumed out with a vacuum pump and then the refrigerant has to be transferred to the appropriate levels in the now closed system. The cost for this work will vary depending upon where it is done and the going rate in that location. The cost of the equipment will be more static but depend upon the capacity of the unit and this depends upon the size of the house.

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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.

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Q. I replaced a fully functional home thermostat with a new digital thermostat from Honeywell. Now neither my heating nor my air conditioning works. I have 5 wires white (W), red (R), green (G), blue (C) and yellow (Y). When I cross a wire with red nothing powers up, so its not the thermostat: for example, crossing red with white should turn on the heating. My breaker box shows all the breakers are enabled. I see no breakers or switches on or near the heating or air conditioning units. I've also reset all the GFCI outlets. What could I be missing? I hate to have to call an HVAC expert out here to kick a breaker or something silly. This has to be something simple. HELP!! More... The furnace is in the attic; Its difficult to work with. I prefer to test with the air conditioning that is just outside the door. Tests for just the furnace don't seem to explain why the air conditioning does not work either. Much more... The house was built in 2004. Much much more... I found the furnace documentation nailed to a 2x4 in the attic; actually its more of a crawl space: a real pain and dangerous to get to and move around. Yes, I was incorrect, all wiring for the air conditioner (AC) appears to go through the furnace, so I can not just test the AC. I now believe that I was working with a live wire (R); I tuned off breakers marked "AC", but there is no breaker or breakers marked "Furnace". Based on the documentation, its likely I blew out the fuse on the furnace circuit board, a 3 amp, 32 vac fuse. I will go buy a new fuse today and climb up into the attic tonight to change it out. Thanks for the hints on the fuse; I'll look around for another breaker box too. Conclusion.... I picked up a fuse at the local auto part store; Home Depot didn't carry the type specified by manufacturer. Once I figured out how to open the second part of the door, there was the purple fuse. I pulled it and saw that it was burned out. I replaced it, went down to the new thermostat and started-up the furnace. A whole lot of drama for a 50-cent fuse. Thanks everyone!

A. Open up your furnace and see what wires go where. The R and W on the board are for heat, but they don't always set it up colour coded like that. Check for an auto style fuse on the board, usually a 3 or 5 amp (purple or yellow). You may have blown that if you put the C (common 24 volt) wire in the wrong place or crossed it with something else. Add on: If your fuse in the furnace is blown, it won't relay the signal to the AC. Nothing will work. You have to check it. If you didn't power down the furnace while replacing the stat, chances are you crossed the 24 volt with something and popped it. The thermostat does not need 24 v to work if it has batteries in it, and a furnace from 2004 will more than likely NOT burn out the transformer. The transformer will pretty much out last any other component in a furnace.

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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.

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Q. We desperately need an exhaust fan installed in our upstairs bathroom. There is one tiny window, which is not enough to expel all of the moisture (esp. living in FL!)... and no air conditioning vent. The bathroom is located on an exterior wall so I wouldn't think it would be too complicated. I just don't know who I should call to do it.

A. Actually, either one can do this job. When building new houses the electrician sets the fan housing and runs the wires, then the AC man runs the duct work when he roughs in his AC unit. Since there's gonna be a switch involved, I'd call an electrician first.

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Q. The filter is completely frozen over with ice we cant even remove it.

A. Shut the AC off and let it defrost. Thats usually caused because the filter clogged from not being changed or cleaned. When the filter clogs, air can't circulate and the coils freeze up.

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Q. I am trying to find out how the sanitation process works and if it causes chemical smells in the house? I'm starting to use the air conditioner in our new apartment and everytime it comes on I end up with a headache and the air smells musty. I have been informed by the air conditioning company that it needs to be cleaned and sanitized, I am concerned about the chemicals they will be using as I am senstive to chemicals. Anybody have this done before and know how it effected your home?

A. I have asthma,allergic to dust. We had our furnace ducts/pipes cleaned out ! I had no problems. The ho user is 6o years old. I do not think the pipes were ever cleaned. You should have no problem if it is a repitule company

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