Air Conditioning Testing

Bill Instructor Illinois Posted   Latest  

Has anyone ever used an Anemometer to check/test an a/c system condenser air flow? I know it is used in business and residential HVAC for measuring vent flow rates and volume.

I have run across a worksheet that includes it in the testing procedure but have not ever known of any one who has used it.

I thought I would reach out and draw on a larger group to see if someone had.

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Glenn Owner/Technician
Texas
Glenn
 

They use them in Home and business HVAC work to test for appropriate air flow at the vents and air intakes. Those system are much larger and have long duct work and sealing them is vital for effective AC cooling. With automotive AC it is kind of overkill because the system it mostly contained. It is pretty obvious if the blower fan is loud it is moving air, if the air is not coming out the vent…

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Steve Instructor
Ohio
Steve
 

I use it as show and tell when I teach, but have never used it for diagnosis.

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Eric Owner/Technician
Wisconsin
Eric
 

Bill, I use one regularly during the summer months. A long time ago on iATN, Glenn Farrell, an Air Conditioning Tech/Shop Owner in Kenner, Louisiana talked me into using one and I've never stopped. I use it about equally on the condenser/radiator and on the vehicle interior. It is nice to use for checking air flow through the condenser and checking how well a fan clutch is working. I used to…

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Martin Instructor
British Columbia
Martin
 

Hi Bill. Yes, I've used an anemometer, mostly for condenser and evaporator air flow years ago. The area I live and worked in at the time, had a high number of cedar shake and shingle mills and the fine dust quickly clogged both heat exchangers, resulting in various concerns. I learned early on, the value of cleaning those two components to snag that elusive couple of degrees of performance…

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Martin Owner/Technician
New York
Martin
 

Jerry Truglia from ATTS used a similar rig on an AC training video to check/measure airflow. For me, it's been the kinda thing that u just feel with your hands but with science, there is always something more practical, accurate and one that can create and follow a standard.

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Glenn Owner/Technician
Texas
Glenn
 

Hi Martin, You brought up some good points. Last summer at around 102 degrees out, my daughter brought me her Honda Fit with a complaint of poor AC cooling. It had about 80 degrees at the duct outlets. The cabin fan was not the problem and the AC pressures looked good. I looked at the condenser front face after removing some trim and air baffles and found the condenser was fuzzy looking from…

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Martin Instructor
British Columbia
Martin
 

Exactly Glenn. The cleanliness of the evaporator and condenser is more than ever before so important with these tiny A/C systems, having extremely low refrigerant volumes. I used to pull out the blower module or resistor and carefully washer the debris away. Sometimes, I'd pull the blower motor to access the evaporator core and use a length of rubber vacuum hose on the end of a low pressure…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Martin, I recall back in the 90's and early 2000's When grass and chaff were a huge problem with many vehicles, especially for people who often went to their kids ball games (parked in the out fields) or worked in the fields on ranches and farms. Those became very common for me. Usually they came in and wanted a 2nd opinion because some other shop had unloaded the parts cannon playing the…

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Bill Instructor
Illinois
Bill
 

Thanks for the tip on the backwards blower wires. I may use that

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Richard Instructor
Florida
Richard
 

It’s something we bring up in a few CTI A/C classes. Since you can get one on Amazon for about $20 that tells you air speed and air temp, it’s a quick way to collect some data. Collecting Known good wind speed values might help us determine if we have a blend door, condensor or blower motor issue.

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Christopher Technician
Texas
Christopher
   

I used to do residential and commercial HVAC work. While I use my anemometer from time to time, it's for measuring airflow output from seats, not A/C - and the readings I get from that are only useful because I have plenty of vehicles to compare readings to (with a custom made funnel). It's not comparable because it's easy to get CFM ratings for commercial and residential HVAC components, along…

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Bill Instructor
Illinois
Bill
 

Agreed, unless you have some references of your own I see little use. LOL sling psychrometer! I had forgotten about the humidity testers

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Glenn Owner/Technician
Texas
Glenn
 

Hi Bill, You are bringing back memories of when I was in the Air Force. We conducted a “Wet Bulb Globe” Temperature test to determine the overall humidity and ambient temp. Then we would display the appropriate safety flag (Yellow, Red or Black). This was conducted in Summer months especially on training bases. The last thing we wanted to have happen was people dropping from heat stress or heat…

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Richard Owner
Georgia
Richard
 

Yes, I use an anemometer and have for a long time. You get numbers and with numbers you make better decisions. If Eric has his notebook where he kept a record of his test results, he should consider publishing it. He would make money and I think it would sell. The numbers for any given vehicle are the hardest part of the equation. The engineer that designed the system knew the numbers, but I…

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Martin Instructor
British Columbia
Martin
 

Many years ago when Clutch Cycling Orifice Tube (CCOT) systems were introduced, we were taught to quick check for the approximation of the refrigerant loop function, by placing the index and second finger on the evaporator inlet tube beyond the orifice tube and then on the top of the accumulator. If both felt the same, it was considered a reasonable assumption that the refrigerant loop was…

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Richard Owner
Georgia
Richard
 

One of the first questions I asked students in an AC class was “Is the refrigerant in the low side a gas or a liquid?”. The answers always amazed me that these were technicians working on AC systems. Our government allows anyone to walk into a parts store and buy refrigerant. DIYers and technicians that know nothing about AC can destroy the system and the environment with no penalty what so…

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Martin Instructor
British Columbia
Martin
 

Hi Richard. Thanks for the kind words. It's good to see others like yourself, continuing to attempt to maintain some semblance of useful interaction in these challenging times. In class, I used to draw a TXV refrigerant loop on one white board and a CCOT loop on the other, then identify the two pressure restrictions (expansion device and compressor), the heat exchangers (evaporator and…

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Bill Instructor
Illinois
Bill
 

That reminded me Richard, working on a Mercury Cougar years back. The pressures and cycling rate clearly indicated a restriction in the system especially since there was frosting at the OT. We suspected possible compressor failure also. After talking to the customer about this come to find out that her “hubbie” had decided to recharge the system because it stopped working. Apparently he started…

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Richard Owner
Georgia
Richard
 

Overcharged systems are quite common for us. It is amazing what a DIYer can do. Very common for us to open a line and have enough oil come out to service my Duramax engine. Many times there will be empty cans of miracle repair in the floor boards of a car. How they do it without maiming or killing themselves amazes me. The cruel side of me says, if they get killed it will take them out of the…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Martin, I'm sure you remember the issues with using a sight glass on the drier. That was meant back in the R-12 days and it would get a person close, but when R-134a was introduced people were still trying to rely on the sight glass a quick reference. Of course when they tried using only the sight glass as a quick reference, there were a lot of system getting overcharged. One Body shop I…

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Martin Instructor
British Columbia
Martin
 

Hi Glenn, yes I remember the sight glass issue as clearly as if it were yesterday. The way that the lubricant moves around with R134a negates the value of using the sight glass and techs would continue adding refrigerant until no bubbles flowed. The appearance of bubbles is lubricant. Sill thing is that there are still sight glasses on receiver driers and we haven't legally been able to use R12…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Martin, Yep, you got it. It seems the thought of training in a body shop is like kryptonite. I have worked body shops off and on since the 80's and not much has changed. Once when I was a technician in a body shop taking care of all the mechanical stuff, I attended many I-CAR classes. At the time I was a certified Master ASE Technician and a Master Collision and Refinishing Technician…

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Martin Instructor
British Columbia
Martin
   

Hi Glenn. My first job in Canada was in a body shop close to home, while I was awaiting the arrival of my mechanical tools. I had experience in body and frame repairs, refinishing and mechanical in England, since small shops often catered to all repairs. I po'd others in the shop off, because I was capable of a wider range of repairs than their skills. The painter always inspected vehicles…

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Eric Owner/Technician
Wisconsin
Eric
 

Richard, I don't know where my notebook is or if I even kept it. This was back in the late 1990's early 2000's. I only used it to keep track of the area farm equipment and pickups I worked on. It made it easier to show how the radiator/condenser or HVAC filter needed cleaning if all I had to do was take a measurement and compare it to the known good I had in my notebook. After a few years of…

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Richard Owner
Georgia
Richard
 

I think computers made me lazy. For years, I kept notebooks on many known good vehicles. I can't explain why I would write things down but won't enter them in a computer. I somehow managed to loose a box full of notebooks in a move. Many years of my life went with that box. I do think, a book with values gained from experience would sell. I may get around to something like that if I ever retire.

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Mike Educator
North Carolina
Mike
 

I have not come across anyone doing that. It seems like it would give good data, but I suspect that you would need to create your own known good database. No doubt it would be more definitive than the old “hand test”. My old crude test method was to see if the multi copy paper work order would stay stuck to the condenser by the fan draw.

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Martin Owner/Technician
New York
Martin
 

In the case of condenser efficiency wouldn't the in and out temperature ratio be a fair measure to kick off the air flow concern/diagnosis ??

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Mike Educator
North Carolina
Mike
 

Delta T is always a good test.

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Bill Instructor
Illinois
Bill
 

Im surprised to see a really good response to this questions and appreciate all the info. from the replies. Thanks to all for taking the time and interest. This really is a great meeting place for people in our fields :)

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