20 Causes of Low Indoor Airflow on Furnaces and Air Conditioners! 

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One of your best videos yet.I really needed this,you don't know how many jobs I see that have low air loss problems and I see techs just think it's a low refrigerant problem...

Very, very good video about a problem that service techs will see almost daily in our trade.

Thank You! You are a great teacher who is motivated with great pride for excellence. Keep it up

What a video well explained, I’ll have one of those frozen ones tomorrow, thank you very much

Problem #21 : If you have a thick filter (i.e. 5"), the cardboard separators between the filter fins can get displaced making the filter fins collapsed over each other. This can happen with a brand new filter or whenever you pull it in and out. It took me a few days to figure this out after checking most of the potential problems listed in this video. I hope writing this here will help someone and make your day! Great videos by the way, thanks for sharing!!!

As a home inspector, I see this stuff all the time, especially shootie workmanship

Craig, every video is just amazing, hugs bro

Very good video!

Very informative video. Thanks again.

Excellent video. Thanks.

Good video. Just received your book. Reading through it now. Great tips.

I love your content. Trying to learn as much here. Appreciate every upload every explanation every details

Helpful information, thank you for sharing !

Great video that covers a lot in a short amount of time!! Definitely educational and practical.

Thank you!

very informative and TY

excellent explaining as usual craig. two thumsbs up

Thank you for this small but very informative video. Learned some new things from this video today.

Very nicely explained,god bless you.

Great video, things the owner needs to do because the builder cut corners, or hired bad contractors

Great. Thanks for the vid bud!

Thanks alot

Craig is the GOAT

Great job and video

Great info

Good video lot's of information. 👍👍

Good vid Craig ...

Was doing a furnace inspection last Fall and found the High Limit had been bypassed. Thinking the limit may be bad I put a new one in. That didn’t work. It is a 3.5 ton unit. It had 2 x 12” return ducts each 50 feet long , poorly installed and one was completely collapsed. This unit had been operating this way since it was installed. New return duct work was installed solving the problem.

Hi there, Craiglemmeachoo. Thanks for the video! Cute cat.

Great video! A clogged drain line will also cause a frozen evaporator coil, the water will start to freeze and form ice on the coil.

Very useful video

Can you make a video on how to figure out whether or not a house has enough supply registers and how to figure out if the return grilles are sized properly, please?

The cat was very appreciative that you moved to the furniture just for it to lay across the supply register...

Another airflow problem I have seen many times on mobile homes happens on down flow systems with a clogged or cracked / corroded condensation drain. The overflowing water will pour down into the 12" crossover duct, completely filling it and causing half of the home to have air, but no air to the other half of the home.

One thing I experienced lately was the blower spinning in the opposite direction creating static pressure and little airflow. Reversing the polarity (swapped positive and negative wire connections at motor) corrected the blower. The blower motor controller module was replaced previously and just happened to cause the motor to spin in the opposite direction, which wasn't noticed until the home owners noticed the AC would not get to the set temp.

Nice sir👍 Thanks

Great Video. Thank you for sharing . How do I check and diagnose bad Metering Device and fix , replaced it ? Thank you.

thanks, partner for sharing!!!!.

16-year-old 2 ton AC outside unit and coil and gas furnace in the crawl space. Replaced with 3 ton outside unit and coil. Did not change the blower and furnace. I see extensive sweating around the coil, and all the ducts/return etc...; moisture build on the ducts work. Cool is set to high in the blower. Since we have increased the capacity of the AC unit to 3 tons, do I need to replace the blower motor? How do I measure what CFM currently motor is at.

Ty nice video

I had a call back on dirty air filters. the filters were checked during the PM. I checked for a leak and when I was done; I decide to go under the house to check for damage to the ducts. I noticed the EAC and my first thought was to open it. the filters were slammed with dirt. I removed them and told them they had to get a price on a new coil.

Good job I see this crap alot now I found out the hard way bout the secondary heat exchanger clogging plus dont use those 3m filters unless you oversize the filter grill

Remember an open return or supply in attic or crawl is a 1 2 punch, not only are you losing that CFM to outside, but that same amount of outside air CFM must enter or leave the home to make up pressures.

Awesome videos! Thank you, I found a flex duct in attic that had romex laying over it at the gable end of house, attic vent let sunlight in and broke down the flex so the romex tore through it and caused low flow to room.

Great video and info!! Sir where are you located?

Thanks!

I wish I could figure out why my system has low air volume. Its an older goodman ARUf with a time delay relay that has the purple wire in the COM on the relay and the black wire in the COM on the circuit board. I wonder if these need to be switched, as someone had replaced the motor recently. Hmm

I read the article what im dealing with is Low Vapor Sat Temp, high Superheat, Normal to High Subcooling, but i changed out the txv twice?

2:37 for the win!

I love your videos maker more👍👍😄😄

The proper way to check airflow is with a magnahelic gauge. This should have been done on start up. Most residential equipment is designed to run at no more than .5” total external static pressure. If the pressure is higher, it will affect the CFM capability of the blower. You can take the reading on each side of the system to determine what is restricted, and then work from there.

Have a Bad Evap Coil furnace Over Heats.Can you Remove the Coil & Run the Furnace Without TiLL the Summer then Replace it?

My insulated line connected to top of the inside unit has some ice and is wet . Not kicking in full power just partly running

I have a Energy Saving Products HV-140 with 42 vent and the unit wired for high speed. The back of the unit is open with a 25" X 16" X 1" filter. The unit doesn't seem to put out the air it should be putting out.

I worked 10 yrs for a school district, my 1st air flow issue was on a ancient 10t that had about 4-5" of ice inside and the sieve on a 3" shaft had spun, for whatever reason the key was gone, whomever had repaired it, was too lazy and opted to just drive the set screw into keyway and it destroyed the shaft ($2k,later)

Thank you for detailed to the point info. You mentioned one reason for air movement slow down is the insulation get sucked in and blocks the air. In my case, when I have the ac on for maybe few hours, the air flow slows down on all vents, I listened to the fan blower and I did not hear any different sound than before. So in your advise it seems something is blocking the air flow. But when I turn the a/c off for 10min and back on, the air is normal, and it stays for a a while for another hour or so. My question is, is there something blocking as time passes or is it the coils icing, or can it be the thermostat? It is very coincident when the other day I removed the thermostat case and put it back, because the buttons were not working well on this, ti change time to program it. It's an old one. Any thoughts? Thanks.

What if you have supply ducts connected to the top of the plenum

Cannot figure it out, I have a very old noisy unit in what looks like a vented closet. The home is double-wide. The airflow through the vents is very poor and sometimes does not work at all.

Hey Craig as always great video very very important aspect that often times get overlooked. I HAVE 1 REQUESTS CAN U MAKE A VIDEO ON A DAMPER BOARD /ZONING BOARD HOW IT WORKS AND TROUBLESHOOT. WOULD LOVE TO GET A BETTER UNDERSTANDING ON THOSE I HAVE NEVER WORKED ON ONE BUT I KNOW ITS ALOT OUT IN THE FIELD. THANK YOU

Just ordered the refrigeration book on Amazon yesterday

I wish there is also one for noisy HVAC.

just purchased a house, and I turned on the A/C it probably lasted 4 hours to go from 80F to 71F, I put my hands over the vents and you could barley feel the cold air, now I'm watching this thinking damn I'm probably going to have to call an hvac guy.

WHat about problem #21 being that the condenser coils on the AC are dirty and blocked with debris and dirt?

Thank you for all your great vids. I was wondering if you can ever have too much return ducting. After watching your videos, I checked my external static and found 3.5 and 3.5 for a total of 7 in WC . Filter drop is .18 INWC ( 5 inch air bear) and a\c coil drop is .21INWC. ( 2.5 ton N coil.) The temp rise is 70 degrees in heat mode. Rheem says 40-70 rise is okay , so I'm at the high end of acceptable . Shooting for 55 degree rise. I'm thinking I might need more returns and supplies but don't want to over duct it. Any help or advice? Also, when is was installed they added one 10' and one 8 inch flexible return duct. this is a 70,000 BTU Rheem 95% that replaced a 115,000 Ruud 95% furnace. Thank you

Mine blows but really weak and we changed evrey filter and it gets hot because no cold air any help

thanks for the video. Mine issue is a litle bit weird. the Airflow is ok when turn on the heat but only little airfow when use only fan or turn on tha AC. Have some technicians here to check but missed to tell me the cause. It would be very grateful if you could help to analyze.

What could cause cold air coming from a register during heating system in our first floor bedrooms but our back bedrooms, family room and kitchen receive warm air? We have gas heat, R-19 walls, 9” flexible insulated ducts and dampers above the furnace. Is it possible a duct came loose way up in the attic and the air being pulled by the return is pulling cold attic air into the duct?

I have a High Efficiency unit. The heat exchanger would have to be removed to clean the underside of a “A” coil I’m guessing???

I just cleaned the fan. 1/4in of dust on each one. It looked like a bunch of rectangles, didn't recognize there were blades there.

Very nice explanation of the cause of low air flow. Most 90* elbows in a duct trunk is equal to 5ft of duct, not all but some are even more equivalent than 5ft. Most common I find is that customers like to move furniture around and cover the grilles, lolol. Maintenance is the Key, clean filter, clean coil. Spot on with all the causes. Very thankful for your professional expertise. HVACR ON AMERICA!!!

I have had so many people remove the filter (to improve performance lol) then replace it with a brand new one right before the service call. The coil wont lie, take pictures and watch their faces when presented with the bill for cleaning it. You suddenly know who told them it was a good idea to remove it cause they look at them all mad.

Will the combination of excess return on the first floor and lack of adequate return on the second floor weaken the second floor supply? In other words, the system overall is getting adequate return, but mostly from first floor. Would this floor-to-floor imbalance result in weak second floor supply? The second floor is hot in Summer by 5 or 6 degrees more than the first floor. I peeked into the first floor return and there's no duct work, just open to the whole wall/framing. Seems like it's pulling air into the return from places it doesn't need to. I was thinking of "ducting" it up with foam board and sealant to force the return to pull more air from the second floor just above that whole opening there. Also going to run jumpers from isolated second floor bedrooms to the main hall/return.

Thank you for sharing. I rarely handle the ductwork on install or sales. You got me

I think the kitty-cat stole the show at 2:35...

Any idea on how you would inspect ductwork with no access to attic and most ducting under the floor or behind drywall?

I know 1” filters are disliked by many, but retrofitting isn’t in the cards. What 1” filter would you recommend? I like the fiberglass but I’m worried whatever passes through will land inside the system.

Hello sir. Quick question about return grill too small or dip switch set wrong. Hime owner says systems had been working fine for years , the it can’t be bad installation right?

have a mobile home with the duct work inside blankey on both sides of home no way to inspect without destroying insulation blanket

So i have a Duct that blows so much air and blows the most air it's a smaller duct, and i have it taped because of that. we just got a HVAC replaced. but it's not distributing enough air to the rest of the house. how can i fix this. thanks in advance. also our ducts are quite old. probably the seals are worn.

Are ducted systems still popular in America. Because from what I’ve seen when I’ve been on holiday to the U.S most houses seem to use ducted a/c & combustion units. In Britain where I live and most of Europe we tend to use more D.X a/c systems and for heating we have more wet heating systems with radiators etc.

How do you measure or calculate each room in terms of capacity?

just installed a brand new AC system but my daughters room and my room air doesn’t flow with force it’s lagging tech told me something about 3 inch rubber where it should be wider to 7inches or wider don’t know who to trust no more

I've got a buddy that's supposed to come over but I figured I would give it a shot on here. My high temperature limit switch keeps killing my furnace. My filter is clean and even when I bypass my high temperature limit switch it's still shuts off and throws the same code. My buddy came over and clean the flame sensor because he thought that it was possible that the fan isn't aware it needs to kick on because the flame sensor was so dirty. Anybody has any more suggestions let me know. I've never cleaned my evaporator coils didn't notice a thing that needed to be done. I've lived in this house for 4 years so I know it's been at least 4 years that they haven't been cleaned. I looked at it from the top and it didn't appear to be crazy dirty. However I couldn't get a good enough angle to see it from the bottom.

The people that do our yard work (HOA) were taking their blower and blowing into my garage (closed door) and front door. I couldn’t breath and couldn’t understand why. I caught them so I know why now. Called my air conditioner people and the problem is dirty blower wheels. $400.00. Four year old air conditioner on the roof. Apt. Next month to clean it.

Hey Craig my Linux thermostat that will not come on And somebody had changed the wires and cut off the old one and added a Black pull out fuse nd the repair man is going take forever I would like to see like a fix myself can You are someone help please I'll Email you a picture

👍

Is it possible for a duck to make a nest in a duct

👍🏾👍🏾👍🏾

19 problems a technician can fix and one problem that is intermittent and hard to price the repair of @2:31! 🤣

ahh, the game of find the supply registers, only improved upon by the game of "find the return grilles" why doesn't my system heat and cool? you can hear the ducts screaming like a banshee upon entering, well uncover, clean and open all the vents..... I've seen countless of them covered over because "they gather pet hair and dirt", yeah, that's why you have a vacuum cleaner I reply (facepalm)...

3 ton system (oversized tbh) 9 supply runs of 6 inch pipe, so roughly 900cfm they got 5 runs closed off and even had 3 of them covered with giant magnets to keep their rabbits from getting cold sooo.... 4 6 inch runs to pump some wimpy airflow for 3 tons of air conditioning in humid illinois. Yeah they were pissed when i gave them an earful about their bullshit. They cooked the outdoor unit from years of that bullshit too, i couldnt get the charge dialed in right anymore. Gave up and told them to keep all the registers open from now on and control the temp off the thermostat like a normal human being.

i think ductless split unit is the future....

Just my bedroom is the only one that doesn't flow properly

2:36 what air supply are you talking about? 🤣

Another biggie : failed Motorised dampers, failure either mechanical or electrical. Or a closed off fixed damper blade.

The subtitles never get your name right. Today you were crema clap

mark

What is this guys name it sounds like he says crummy gleotchu I am not trying to make fun but I just can not make it out.