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 have an outside central air conditioning unit, it is approx. 80 degrees outside and extremely humid, also very hot inside the house with fans running. The air is set to 70*, yet the air coming out of the vents feels to be room temperature and is NOT cooling the house down. Approx. two months ago, the landlord had a technician come out, and he said we had a slow freon leak, and although he filled it with freon, I was told he did not fix the leak. What is causing the air conditioner to do this? I cannot go in 100* weather without air conditioning. Any help would be appreciated :) and thanks in advance!

A. It almost sounds like the tech overcharged the unit. Either way he is supposed to fix the leak. He was not supposed to add refrigerant to a system known to be leaking. Make sure the fan is working on the outside unit. If it is not the system has no way to remove the heat from your house. Ask your landlord to call a different tech out to look at it. This guy was a fool.

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Q. Please excuse my ignorance, but is there a portable air conditioning unit (blows out COOL AIR in a HOT ROOM) without being attached/fixed to the wall, as in carry it with you just plug it in to a wall socket and have it blow out cool air. I know this may seem like a dumb question, but a simple answer would be much appreciated. Thank you!

A. There are two units that are kind of like that, but not quite. one is called a swamp cooler. they evaporate water to absorb thermal energy in a room, but make the room more humid, and only really work in dry climates. however, they are relatively cheap to buy and use little energy. the other is a regular AC unit, but, this is not a window unit. they make one that is a free standing floor unit that can be pushed around and plugged in anywhere. however, the only downside is that there is a 3 or 4 Inch diameter hose that comes out of the back of the unit that must be run outside, through a window or a cat door or something. the unit is similar to window units in that it must move the heat from the room to the outside, but it does not have to hang out the window. they are about as expensive as regular window units. and are much more portable. you just have to point the hose outside. just remember, the heat has to go somewhere. it is very hard to just make it disappear (like an endothermic reaction, a reaction that takes heat)

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Q. If you know someone that has and operates their own company, not a big company where you have to wait on hold when you call them i'm adding some rooms in my house and need some bids for the a/c thanks

A. Honest Air i dont have the number but you can find it online good luck

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Q. What is it, and they claim that it can cut air conditioning costs by upto 50% where can i find such contractors

A. There are some cold roofing that is available to make sure the roofing is not only NOT leaking but also it reflects a lot of heat back( if you are in a tropical climate) or act as insulator if you are arctic climate. there are many types roofings that you can do . you can google them, or check the site, you can at least get some basic information on what to expect.

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Q. Water sometimes backs up and my unit turns off. I have to shoot water into the PVC pipe outside and suck it out to get it going again. Are you supposed to put bleach or something else in the PVC pipe?

A. I used to have this problem but when I got a new unit install they put a clean out opening in the condensate pipe up in the attic. I just poor a little bleach down the pipe a couple of times each season. No more problems.

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Q. This question concern central air conditioning. Like most homes with central air, our compressor unit sits outside of the house. Unfortunately it sits on the side of the house where it is in direct sunlight during the afternoons, which is also the hottest part of the day. Our air conditioner runs pretty much constantly all afternoon. I have been told that building a carport type shelter over the compressor that would shade it from direct sunlight will help it runs more efficiently. the idea makes sense to me, but I am not an expert. How much would this really help? I mean if we are talking a 1% or 2% increase in efficiency that it would hardly be worth the effort, but a 10% or 15% increase is a significant difference. Does any have experience with this? By the way, I already know about the standards tricks, such as the house being well insulated (it is), changing the filter at least once a month, having the unit serviced once a year, etc. I am asking specifically about shading the compressor. Harley - interesting tip, thanks. I have never even heard of solar powered water panels, is there a web site where I could research this further? Roy - I had heard this, in fact the person who suggested I build the cover told me to make sure there was enough room. Looking at my question now I don't think 'cover' was the right word to use, I am not talking about covering it with a snug cover like a car cover, I mean a canopy style covering that would be at least a foot over the top to allow the air to circulate. Does that make more sense?

A. Simply without getting to technical, shade is 20 t0 30 degrees cooler. That makes the unit head pressure lower which makes the suction temperature lower. That's what you get out of the evaporator "air that cools the room" Make a shade spot without restricting air flow. Tall fence or tree.

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Q. Specifically, a 1996 grand am, if that makes a difference.

A. Are you doing it or a shop, new parts or used, what is wrong with it, what part of the country are you in, AZ ac prices are double what they are in SC

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