Q. Air conditioning costs more but what exactly is the difference between the two systems? Is air recirculation effective at cooling or heating the vehicle interior on hot or cold days?

A. Air Recirculation and/or the Max A/C button do the same thing. They close off the vents that let fresh air into the car from the base of the windshield. Air Recirculation should be combined with A/C usage, which is why on some cars (older domestic US cars in particular) it's labled Max A/C. Air Recirc setting helps the air conditioner system by recirculating already cooler air through the system, rather then trying to take warmer outside air and cool it down. You can use it with heat, but on some cars (older Japanese and German cars in the US) they aren't set-up to run the A/C compressor in defrost mode. Any moisture at all will cause your windows to fog, ALL OF THEM, unless you also turn on the A/C button too. A/C doesn't really cost much more then 1 mpg on most cars. For me personally, I'll use A/C whenever I can. My comfort is worth more then 1 mpg.

Q. I think my AC unit is shot. I suspect the repair to be major, so cost is pretty important to me. Can anyone recommend a dependable repairman or repair service that won't gouge me? Thanks!!

A. Independent HVAC steve baser 214-724-1862

Q. Does anyone know a good website that teach me step by step how to service ( and do commonly needed replacement) my single room (Window /wall mounted) Air Conditioner. Googled website almost all only show companys that do air cond repair. I want this as new hobby ! T H A N K S !!

A. Try starting here: http://www.hometips.com/cs-protected/guides/centairfix.html Google diy air conditioner repair. gl

Q. I just moved into a new home that had never had the ducts cleaned. The house is a ranch with gas forced air heat on one zone with about 9 vents. I found this company on a coupon for $45 which included unlimited vents and a couple access holes. When the company began their work they found mold and the price skyrocketed from $45 to $1400. Does this sound like a screw job or is that price accurate for mold removal and duct cleaning?

A. Mold removal/remediation is entirely different from air duct cleaning. However, it is not uncommon to find mold in your air ducts. That is why we recommend the Electro Breeze Duct Mount UV kit at http://www.allergy-relief-air-purifier.com/air-conditioning-filters.html. This unit will eliminate mold and bacteria from your indoor air and keep your air conditioning coils clean from mold. You must consider that to remove the mold from your air ducts, the air duct cleaning company is entering into a potentially dangerous situation for their employees. This requires expensive equipment and a person with the skills to do the remediation properly. Now that they have knocked the mold loose, you will need the high efficiency filtration and ultra-violet light of the Electro Breeze DMUV kit to kill and capture the mold spores in your indoor air. I hope this helps.

Q. My car is getting older and I've noticed the air coming from the air conditioning ducts and air vents smells musty, dusty, and dirty. Is there a way I can clean the ducts and vents? Also, is this something I can get done at an auto detailer?

A. The answer to your 2nd question first. Maybe?! Some detailers will only clean/restore what they can reach, although there are some who might go the extra mile. The problem is, they don't want to be responsible for destroying your dash vents to get at the ducts. When I worked in a body shop, we simply used compressed air through the vents to blow out the dust and dirt accumulated while the car sat inside being worked on.......some people even put pieces of air freshner directly in the vents to sweeten the smell afterwards.

Q. My doctor told me I need to get my air duct cleaned, but I keep hearing all kinds of horror stories about air duct cleaners. Does anyone knows of a good air duct cleaner near San Francisco?

A. Here are some Union companies that do duct cleaning. They all do good work. Atlas Heating and AC Oakland, CA 510-893-1343 Advanced Solutions Heating and Air Conditioning San Mateo, CA 650-347-4828 Bell Products Napa, CA 707-255-1811

Q. I have central air in my apartment and for the most part it works but lately it has not been cooling down the apartment. Any ideas on how I can fix this? Thank you.

A. How old is the unit and when was the last time it had a freon charge? Unless it has leaks, the ac unit should be checked and recharged once a year. If everything is working, but it is not really putting out cold air, usually an indication of a recharge needed. To verify everything is working: Set the thermostat to Auto, Cool and about 75 degrees. If air is coming out of the vents, the air handler (inside unit) is working ok. Next, go to the outside unit and see if the fan is turning and the compressor is running. (fan by sight; compressor by sound). If okay, all components are working as they should and the unit probably needs a recharging.

Q. Our air broke on Satuday it is now monday still not fix he is saying maybe wednesday we har having heat warning right now

A. He has no legal responsibility to fix it at all. Maybe the serviceman can't get there 'til Wednesday?