Air Conditioning Tune Up Tutorial

I had a home inspector over a few months ago and he said my A/C was blowing low so I I had someone come and look at the system a few weeks ago. I compared a few offers that I received in the mail.

Top Quality - $49 (Diagnosis with one free pound of freon) Certified - $59 (Diagnosis) Sears - $39 (Diagnosis and filter) DBK - $69 (Diagnosis) Harell - $29-$49 (Service call extra) Home Depot - $38 (25 Point Diagnosis)

I went with Home Depot (outsourced it to ARS) because they described what they were going to do the best (over the phone and in the store). Plus I believed I had a leak after reading up on this stuff (will cut and paste the best article at the end) and knew it would be pointless to get the free freon.

A few tips before we get to the service call. 1. Freon or R22 will be outlawed by the end of 2014. The price has jumped from a few bucks to almost $100/lb in some areas. ARS quoted me $69. I probably have a 6-7 lb unit. Some of these guys were touting a free filter. They cost around $2 each in a package of three at Home Depot. By far the lowest price. Don't even think about buying them in a supermarket.

Service Call - He (pleasant fellow) came 1 1/2 hours late. He checked the freon with some kind of pressure gauge. Said I needed 75 lbs and was at 45 lbs. He couldn't add the freon because the added pressure would just force freon out at a greater rate than it does now. Logical. He then did some more stuff around the outside unit and unscrewed the cover to the inside burner. He scraped around the inside, but, did none of the heater inspections or servicing promised by HD. I didn't complain because I know it is fine. He then went back outside and attached a wet vac to clean out the drain pipe. He said he drew out dirty water. I didn't see the wet vac before he used it so I hope it wasn't a slight of hand. I didn't really care at this point because I had just wanted to confirm that I was low on freon and have a leak. The whole process took about an hour.

Impressions - I think this service is a waste of money even if they do what is promised. If you have low output, you have a leak and need to schedule a leak search. They offered one for $280. I have to shop around for a better price. The search doesn't include a repair. Lord knows what they quote for that. The inspection (if done properly) was supposed to help a little (see cut and paste below). My tech said I would see no difference. It made me wonder if he did all the things that he was supposed to. He also said that those commercials for cheap units from Appliance Direct only are sold to commercially licensed customers. I'll have to check on that because they were advertising units around 2k and all the other ones either don't list or I think list around 6k and then give a rebate.

Helpful Article from the Internet...

Air-Conditioning Tips, original prior to 1990?? Edited 07-17-2010 Edited 03-25-12 Edited 07-25-13 The information will help you stay cool and save money by keeping your A/C running at peak performance. It will help assure that your Air-conditioning is keeping you as cool as possible and working and cooling as efficiently as possible while saving you money. And help you decide if you need a professional to service your Air-conditioning system.

(1) Air filter(s) MUST be clean. Filters are located in the return air duct adjacent to the air handler or in a return air grill(s) in your wall or ceiling. Check your air filter every 30 to 90 days to make sure it is clean. Depending of the house, i.e. if you have animals you may need to clean or replace the air filter(s) more often. (Go clean them now!)

(2) Flip the switch or push the button on the thermostat for the fan setting to FAN ON, not AUTO. This will run the indoor fan nonstop. The outside A/C unit will still cycle with a call for cooling from the thermostat. The constant air moving will keep you cooler. You can probably keep the thermostat a degree or two higher than normal and still feel comfortable. You will also maintain a more even temperature between upstairs and downstairs. This will SAVE you MONEY because the outdoor condenser will not come on as much!

(3) Make sure that you wash the outside condenser coil once a year. If it's dirty the A/C will run hot and inefficient. A sign of the coil being dirty is the small exposed copper pipe (tubing) line, usually 3/8" O/D connecting the inside unit with the outside unit will be HOT to the touch.

(4) If the small exposed 3/8" copper pipe connecting the inside unit with the outside unit is hot to the touch there can be several reasons why; (a) A/C is low on refrigerant. (b) The outdoor condenser coil is dirty. These are the two most common reasons for it to be hot to the touch.

(5) "Warm Rooms" on the lower levels of the house where it is cooler cut back / partially cut off some vent registers (Diffuser) but do not close them off all of the way, doing so could interfere with the static air pressure (air balancing of the system.) Make sure that all the ones on the upper floors where it is warmer are open all the way! Also, see paragraphs #2 & #9.

(6) "Doors" if you close the door to a room make sure that there is about a 3/4" gap between the bottom of the door and the floor. You may have had carpet put down on the floor and now there is no gap. This is necessary if you have a central return air duct in the hallway. The return air ducts need to pull the warm air from the room.

(7) Never leave the house and turn OFF the A/C. then come back home and turn it on and expect it to cool the house anytime soon. Doing this will not allow the unit to cool down the house for several hours. You can set the temperature up five to ten degrees but NOT OFF. This is because of Latent heat buildup in the walls and furniture in the house and will make the A/C work harder to remove the heat, this takes a long time.

(8) Never turn the A/C off than back on in less than five minutes, this will short-cycle the compressor and can trip breakers, blow fuses, or cause permanent damage the compressor. You should have a time-delay install on the A/C to prevent this during power outages! Most digital programmable thermostats have a time-delay of 3-5 minutes built-in. Having a start capacitor and relay is a good idea. This will increase the life expectancy of the compressor by starting faster thus keeping motor electrical windings temperature down, using less electric to start.

(9) Keep blinds closed, curtains drawn, window shades down. A working attic fan would be a good idea. Plenty of insulation in the ceiling & walls. Air tight storm windows. Keep outside doors and openings close, etc.

(10) Ceiling or other fans are a good idea, they can keep the air moving and make you feel cooler. Ceiling fans also help with keeping the temperature more even between the floor and ceiling. Note: during the summer ceiling fans should be blowing the air in the downward direction, but in the winter you would reverse the air direction to blow upwards and at a much lower speed.

(11) "Icing of the indoor coil or the large insulated covered copper pipe. There are two main reasons for this, lack of air flow or low on refrigerant. Lack of air flow can be a dirty air filter, dirty indoor evaporator coil, dirty fan blades, damper in duct restricting air flow.

(12) "Water inside around air-handler." The condensate line is a drain pipe coming from the indoor evaporator coil to an indoor drain or to the outside. This can become clogged and cause water to backup and can produce about five gallons of water an hour. This is where all the humidity and moisture from the house goes. This is usually a 3/4" white PVC plastic pipe.

(13) You should NEVER need to add refrigerant (Freon) to a system, if you are adding refrigerant this means that there is a refrigerant leak in the system that NEEDS to be fixed! (Why KILL the Ozone layer?) and running your system low on refrigerant can cause damage.

(14) Checking the cooling with a thermometer. There should be a 15-20 degree (Delta-T) temperature drop across the indoor coil at the air handler. Check the temperature drop in the duct close to the coil, if air coming into the coil is 75 degrees than the air leaving the coil should be 60-55 degrees. If it is higher or lower there is probably something wrong. Too high of a drop, IE more than 20 degrees drop, could mean lack of air flow or low on refrigerant. Less than a 15-degree drop could mean too much air flow, dirty outside coil or low on refrigerant.

(15) Never cover the A/C (Outside unit) with plastic or an air tight cover; this will cause it to rust.

(16) Do NOT let animals (Cats) (Dogs) etc. Urinate on the outside coil. This will cause it to corrode (rust) and then leak refrigerant.

(17) Keep grass, leaves & weeds from blocking air flow on the outside A/C.

(18) Do NOT build a deck close to the top of the outside A/C or anything else that could cause the warm discharge air to re-circulate back to the unit.

(19) Fuses, Circuit Breakers and wires should never be hot to the touch; if they are hot you may have a sizing problem or a loose or bad electrical connection. (20) You can stop hear, the rest may not interest you.

When you need to have your equipment repaired/serviced make sure you use a licensed contractor who should be insured and obtain permits from city/county officials when required/necessary. Or a member of the (PHCC) Plumbing, Heating, Cooling Contractors Association. PHCC contractors are professionals who adhere to a published code of ethics that improves the industry and protects your health, certified by the State Board of Contractors. They also have licenses, bonds, insurance and obtain permits when required by local municipalities. The PHCC logo is your assurance of quality in this profession! Isn't your health & safety worth it? It should be! Call 1-800-533-7694 for more information about the PHCC.

Air-Conditioners DO NOT add cool air. What they do is move warm air from the inside and transfer it outside. R-22 & R-12 ETC.. Refrigerant is a manmade product invented by DuPont and given the trade name FREON. Warm air travels towards cool air. So saying close the door I am trying to keep the heat out would be correct. Warm air rises.

The temperature of refrigerant is directly relate to the pressure it is at and vise versa, ie. R-22 at 0 psi is -40 degrees below zero or at 60 psi it at 32 degrees. This is misleading; the temperature change is NOT related to pressure really, but almost totally tied to the change from a liquid to a gas. When liquid Freon is expanded to a gas it gets really cold (latent heat of evaporation) and when the warm gas is compressed to a liquid it gets hot. The temperature change in say compressing liquid Freon to a higher pressure (adiabatic compression) is small. You see the same effect when you crack the valve on a CO2 or propane bottle for example. You will get a smaller effect with a pure gas, like when you fill a Scuba tank it gets warm or drain it quickly the valve gets cold right at the expansion point, but this effect is not great enough to run an AC system.

The physics of phase change from a gas to a liquid and vice versa drives most weather as well, for example.... With water it takes as (I recall) 560 (or was it 590...) times as much energy to boil water from 100c liquid to 100c gas as it does to raise the same amount of water 1c in temperature. Freon is less dramatic than water in terms of this energy amount, but it boils at a much more convenient temperature for human AC units than does water. If you wanted the inside of your house to be 100c you might want to run water in your AC.

FYI only. ***************************************************** Keep in mind that heat goes toward cold and not cool to heat. All the A/C compressor does is pump vapor to create a high and low pressure, ie. A low pressure at the inside coil for a low temperature for the refrigerant to absorb the heat in the house and a high pressure at the outside coil to give off the heat the refrigerant absorbed from the inside coil to outside. Over sized A/C will run short cycles and not remove the humidity and moisture from the house, an under sized unit will not be able to keep the house cool on a hot day. You MUST be careful to get the correct size A/C for your house. A/C's are sized by tons; there are 12,000 BTU'S to a ton of cooling. ("Ton" means 12,000 BTU'S of heat is needed to melt one 1 ton (2,000 Pounds of ice) You need to move 400 CFM of air per ton of cooling across the indoor coil. 450 CFM for Heat Pumps. Each CFM (Cubic foot per minute) of air will carry 26.7 BTU's of cooling. You need a heat-gain calculation done per room to get the proper (CFM/BTUs) to be delivered to each room and the total (Tons/BTUs) needed to cool the house based on designed weather conditions in your area.

The above is my personal opinion and advice, please feel free to obtain other opinions as I may have got something wrong. (I am sure if I did you will let me know)