DIY HVAC Maintenance - Tips and Resources

[P0234]

I'd like to get into a litle bit more into home HVAC DIY. I've done car AC as well as minor DIY stuff for home. I'm proficient in cleaning the units as well as giving them the basic flashlight treatment. I'd like to pick up a set of gauges and start doing full yearly inspections myself. What should I look into buying and what some good resources are available online? Currently have two places with a total of 3 units and would be nice to help on my parents house as well, all are R410a. First project once things cool down a bit (not going to play with a good working system in the middle of summer!) is checking pressures I think, my delta T's have slowly been declining to the lower part of the acceptable range.

Thanks so much to all the folks (and techs) helping out here and not naysaying. Going to post links to good sources of info below as they get added to the thread or I find them.

Youtube University:
AC Service Tech LLC - lots of great and simple howtos: https://www.youtube.com/channel/UCOZR-1IqsAer9wzlvFgb4mA
HVAC School- more tech centric but good content - https://www.youtube.com/c/HVACSchool/videos

Apps:
Emerson Check and Charge - https://play.google.com/store/apps/details?id=com.emerson.checkncharge&hl=en_US&gl=US or https://itunes.apple.com/us/app/hvac-check-charge/id574809181?mt=8

 

[Jim greengo]

Get yourself a good set of basic gauges and a chart showing pressure/temps for 410a.
And a clamp on thermometer.

 

[metlmunchr]

To check the refrigerant charge you need to be able to read pressures, air temperatures both wet bulb and dry bulb, and refrigerant line temperatures. So, to do this, you need at a minimum....

Manifold gauge set. Yellow Jacket has a good set for around $110 that will do anything you need to do.
Psychrometer for measuring wet bulb and dry bulb air temps.
Contact thermometer for measuring ref line temps

Do not attempt to get temps with an IR temp gun. They're handy for a lot of things, but AC service ain't one of them.

Download the app CheckCharge to your phone or tablet. Free from Emerson Electric, the manufacturer of Copeland compressors. You'll be checking charge via either superheat or subcooling, depending on whether a system uses a fixed orifice or a thermostatic expansion valve. The app has data for a dozen or more common refrigerants. You enter, for example, target superheat from a nomograph in the outdoor unit service data, along with the temps and pressures you measured, and the app instantly tells you the current superheat and whether the system's charge is over, under, or correct. Beats the devil out of trying to remember numbers or do hand calculations.

 

[yeldogt]

All I do is gently spray off the condenser with water and wash down with car wash that includes wax

 

[Terry D]

Basic set of Gauges. The Amprobe meter with measure wet bulb and ambient temps. The Testo clamp will measure line temps. The Fieldpiece temp probe will take duct temp readings for Delta T measurement. But before the charge can be determined if correct. You must have proper air flow across the evaporator. Make sure you have a clean filter and the evaporator is not clogged. There are meters that will measure air CFM, but they can be pricey. You can measure static pressure, but you will need the engineering data from the unit or you can measure CFM with a hot wire anemometer. Around 400 cfm per ton is good. If your delta T is low, it could be to much air flow or undercharged

Amazon.com: Yellow Jacket 42004 Series 41 Manifold with 3-1/8" Gauge, psi, R-22/404A/410A: Industrial & Scientific

Buy Yellow Jacket 42004 Series 41 Manifold with 3-1/8" Gauge, psi, R-22/404A/410A: Gauge Sets - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Amazon.com: Amprobe THWD-3 Relative Humidity Temperature Meter : Appliances

Buy Amprobe THWD-3 Relative Humidity Temperature Meter: Humidity Meters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Amazon.com

Fieldpiece SPK2 Folding Pocket in-Duct Thermometer with MAX/MIN Hold and Stainless Steel Probe: Amazon.com: Industrial & Scientific

Fieldpiece SPK2 Folding Pocket in-Duct Thermometer with MAX/MIN Hold and Stainless Steel Probe: Amazon.com: Industrial & Scientific

www.amazon.com

 

[P0234]

Thanks gentlemen for the recommendations.

I've been eyeing the Mastercool 58161 gauge set, I like that its made in USA. Is the Yellow Jacket that much better?

Also any thoughts on a schrader valve replacement tool? How often do those guys need to be changed?

I've been watching these videos but am always ready to learn more.

https://www.youtube.com/channel/UCOZR-1IqsAer9wzlvFgb4mA

 

[Terry D]

I have the yellow jacket set, don't know about the Master cool. Its good to have a Schrader core tool. Get into the habit after removing the gauges to spray some leak check on them to make sure they sealed.

The guy you linked on you tube is very good.

 

[metlmunchr]

The Master cool gauges should be fine. Honestly, Yellow Jacket, J/B, and Robinair have been standards of the industry for at least 50 years, and it could be effectively argued that all 3 brands are overpriced. I replaced my old set with YJ a couple years ago, and if I hadn't had an immediate need (damaged beyond reasonable repair), I would've shopped for something cheaper.

All gauges and hoses have 1/4" OD flare fittings. 410A systems have 5/16" OD flare connections, so you'll need a couple adapters for that. If you're planning to do anything on auto A/C using 134, you'll need adapters for that. No idea of the connections on cars using Y1234 as I don't do a/c service on anything but my own stuff and I don't own anything using that liquid gold.

Agree with leak checking Schrader valves after removing gauges. I don't attach gauges as part of a general operation check unless there's some specific indication that pressures should be checked. Reason being the propensity of Schrader valves to leak when messed with. Years ago, all service ports on air conditioning and refrigeration equipment came from the factory with brass hex flare caps. The cheesy plastic caps used now are purely a cost cutting thing, and prone to deterioration from the elements over time. I replace the plastic caps with brass ones as a matter of course regardless of whether I'm working on existing equipment or starting up a new system. Couple bucks well spent IMO to actually seal the ports rather than hoping the plastic caps will seal when the only thing they can be relied on is to keep dirt out of the ports.

 

[P0234]

Thanks, yeah, I'm worried about the old schraders but with my upstairs AC unit getting down to about 14 degrees delta T, its time to crack it open and check the pressure, which I won't be doing till fall. I'm good on Auto AC, already have a guage set for that.

Thanks for the info on the flare connections, I would have missed that, doing to add some adapaters to my cart.

 

[Terry D]

The Master cool gauges should be fine. Honestly, Yellow Jacket, J/B, and Robinair have been standards of the industry for at least 50 years, and it could be effectively argued that all 3 brands are overpriced. I replaced my old set with YJ a couple years ago, and if I hadn't had an immediate need (damaged beyond reasonable repair), I would've shopped for something cheaper.

All gauges and hoses have 1/4" OD flare fittings. 410A systems have 5/16" OD flare connections, so you'll need a couple adapters for that. If you're planning to do anything on auto A/C using 134, you'll need adapters for that. No idea of the connections on cars using Y1234 as I don't do a/c service on anything but my own stuff and I don't own anything using that liquid gold.

Agree with leak checking Schrader valves after removing gauges. I don't attach gauges as part of a general operation check unless there's some specific indication that pressures should be checked. Reason being the propensity of Schrader valves to leak when messed with. Years ago, all service ports on air conditioning and refrigeration equipment came from the factory with brass hex flare caps. The cheesy plastic caps used now are purely a cost cutting thing, and prone to deterioration from the elements over time. I replace the plastic caps with brass ones as a matter of course regardless of whether I'm working on existing equipment or starting up a new system. Couple bucks well spent IMO to actually seal the ports rather than hoping the plastic caps will seal when the only thing they can be relied on is to keep dirt out of the ports.

410a mini splits are 5/16. Condensers on standard 410a systems are 1/4, at least the ones that I have attached to

 

[bonneyman]

As much as I applaud DIYer's and trying to fix your own stuff, I would advise against doing so on your HVAC system. I've had to repair so many screw ups from customers - even well intentioned, skilled DIY types - that it's not worth it. Especially in todays climate where a simple mistake will be taken advantage of by the typical A/C company.

Stuff you can do: Keep the filter clean, clean out the condensate pump yearly, wash the outdoor coil in the spring, wax the unit outside down with a paste wax - sure. If you're really feeling froggy you can take the condenser fan off the top and vacuum out any leaves and debris from the bottom of the outdoor unit. Keep the dog from peeing on the unit, keep weeds and other debris away from the outside. Doing this stuff religiously will save alot of grief and not overly expose you to avoidable hazards.

 

[karoc]

After you check it then what? Go to your local Jr college and sign up take some basic courses that will give you more knowledge than just looking at psi. That where I got my start about 40yrs ago and it hasn't gone to waste, even as a DIY it don't hurt to know little more.

 

[P0234]

As much as I applaud DIYer's and trying to fix your own stuff, I would advise against doing so on your HVAC system. I've had to repair so many screw ups from customers - even well intentioned, skilled DIY types - that it's not worth it. Especially in todays climate where a simple mistake will be taken advantage of by the typical A/C company.

That didn't take long. So you're an HVAC tech. How many successful DIY repairs have you been called to inspect? Instead of warning us against it, maybe you could share some stories so we don't repeat those mistakes. I think a few of us can share some pro screw ups. A pro installed my TXV valve with duct tape... among other fun things.

And taken advantage of? What, like you mean to sell me a new unit? I have 4 and 9yo units and live in a metro area. 9 out of 10 "techs" are going to try to sell me a new system due to "the old and unsafe unit" I got nothing much to lose. In my neighberhood these aholes were replacing 3 year old units. THREE!!!

 

[Jim greengo]

Thanks gentlemen for the recommendations.

I've been eyeing the Mastercool 58161 gauge set, I like that its made in USA. Is the Yellow Jacket that much better?

Also any thoughts on a schrader valve replacement tool? How often do those guys need to be changed?

I've been watching these videos but am always ready to learn more.

https://www.youtube.com/channel/UCOZR-1IqsAer9wzlvFgb4mA

Screwdriver like they use for valve cores on tires works fine,most of the time they just need tightened up is all.

 

[bonneyman]

That didn't take long. So you're an HVAC tech. How many successful DIY repairs have you been called to inspect? Instead of warning us against it, maybe you could share some stories so we don't repeat those mistakes. I think a few of us can share some pro screw ups. A pro installed my TXV valve with duct tape... among other fun things.

And taken advantage of? What, like you mean to sell me a new unit? I have 4 and 9yo units and live in a metro area. 9 out of 10 "techs" are going to try to sell me a new system due to "the old and unsafe unit" I got nothing much to lose. In my neighberhood these aholes were replacing 3 year old units. THREE!!!

And that's one of the risks of giving free advice.

 

[P0234]

And that's one of the risks of giving free advice.

I wish you'd share your DIY horror stories. The garage journal bunch is generally DIY save for a few. Sure would be great to learn from other's mistakes.

 

[quickfarms]

I have been doing the basic stuff for 30 years now. Being in the construction industry I know some honest and helpful techs. These guys will try to diagnose my issue over the phone, they are few honest ones out there. Personally I do not own a set of gauges because if I find an issue I have no way to charge the system.

I have heard about, and seen, more issues created by techs than good DIY people, just know, or learn, the limit of your skills

 

[bonneyman]

I have been doing the basic stuff for 30 years now. Being in the construction industry I know some honest and helpful techs. These guys will try to diagnose my issue over the phone, they are few honest ones out there. Personally I do not own a set of gauges because if I find an issue I have no way to charge the system.

I have heard about, and seen, more issues created by techs than good DIY people, just know, or learn, the limit of your skills

Proper charging is one of the most difficult techniques to master. Actually, the "art" of charging would be more accurate. Even many techs don't have it down.

Most A/C systems have charges that need to be accurate to within an ounce. Of course, they will function if a little over or undercharged, but few people can measure refrigerant to the needed precision. I have an electronic weight scale that measures down to a 1/10th of an ounce. And still have trouble getting the balance just right at times.

 

[FMB4]

As of 2018 the EPA section 608 of the Clean Air Act allows only certified technician to purchase Freon for home AC units. This restriction includes refrigerants such as 410A, 134a, and 404A. See the exact wording from the EPA's website.

Note: I am not a fan of the EPA.

 

[bonneyman]

As of 2018 the EPA section 608 of the Clean Air Act allows only certified technician to purchase Freon for home AC units. This restriction includes refrigerants such as 410A, 134a, and 404A. See the exact wording from the EPA's website.

Note: I am not a fan of the EPA.

Agree and agree!

I figured the glaring "loophole" of letting homeowners buy freon was going to be closed sooner or later. How many of us used the canned R-12 on our cars, and could buy them for $1 down at the auto parts store over the years?

 

[metlmunchr]

410a mini splits are 5/16. Condensers on standard 410a systems are 1/4, at least the ones that I have attached to

You're correct. Mini splits are the only 410a equipment I've worked on in ages. Been out of the money making end of the business for a number of years and only do service work for friends and family, and so far none of those with 410a systems have had any problems that required any repairs on the refrigerant side.

 

[bonneyman]

I just mentioned it to PO234. Check out MicroMark. They specialize in tiny tools. They offer some micro screw starters for ultra tiny screws. An absolute lifesaver if you must work on electronic t-stats and control boards. Work well on computers and probably smart phones, too.

Micro Screw Starter | Phillips #00 Precision Tool | Micro-Mark

Start tiny Phillips screws with ease using Micro-Mark’s Micro Screw Starter. Spring-loaded tip securely holds #00 screws for precision placement.

www.micromark.com

 

[C2F]

If the systems are mini splits there is alot more involved than superheat/subcooling for proper charge.

for standard on/off by contactor systems. If I were you I’d replace the wear items. Contactors if they look worn and if the system is getting close to 10 years. replace the capacitors, they are like 4-10 bucks each. Check all the wired connections and tighten them.
For the indoor air handler pull out the blower assembly and blow the motor out. See if the motor is one that requires oil. Check out your heat exchanger while the blower is out. If you have a TXV (a bulb on the suction line), make sure the bulb is very tight to the suction line and well insulated.
If these units are not rentals I’d suggest upgrading the indoor air quality. Add a humidifer, better air filtration, and if within budget a REME Halo LED.

 

[PoorUB]

To the OP.
If you want to do it properly, you need to learn how to measure subcooling and superheat. and then understand what your measurements mean. It is not just slapping of a gauge set and looking at the pressures. Doing this a couple times a year I doubt you will be comfortable doing it.

I agree, I find it sad that most HVAC techs don't do proper testing. Without understanding what the measurements mean you will be no better than the lazy hack tech and maybe worse.

 

[P0234]

To the OP.
If you want to do it properly, you need to learn how to measure subcooling and superheat. and then understand what your measurements mean. It is not just slapping of a gauge set and looking at the pressures. Doing this a couple times a year I doubt you will be comfortable doing it.

I agree, I find it sad that most HVAC techs don't do proper testing. Without understanding what the measurements mean you will be no better than the lazy hack tech and maybe worse.

So what does that exactly mean? My plans weren't to learn the math behind the concept, however I was planning on understanding the relative pressures to help indicate what is going on in the system. To be frank, I'm probably not even going to do anything with those numbers until I can bounce it off some folks.

 

[grounded-b]

So what does that exactly mean? My plans weren't to learn the math behind the concept, however I was planning on understanding the relative pressures to help indicate what is going on in the system. To be frank, I'm probably not even going to do anything with those numbers until I can bounce it off some folks.

That means that the pressures alone, don't tell you anything about the system, other than maybe, it's totally empty of refrigerant. Pressures in the system vary greatly, depending on outside air temp, indoor air, dry and wet-bulb temperatures, and whether you have a TXV, orifice or piston type system .

Steve

 

[Terry D]

So what does that exactly mean? My plans weren't to learn the math behind the concept, however I was planning on understanding the relative pressures to help indicate what is going on in the system. To be frank, I'm probably not even going to do anything with those numbers until I can bounce it off some folks.

As stated pressures alone wont tell the whole story. But you need to get familiar with using a gauge set. You need to know how to hook it up and purge them. Its all about temperature/pressure relationship. By reading the pressure, then you can convert it to temperature. Depending on what refrigerant you have, you take that temp and use it to figure super heat or sub cooling depending on what metering device you have. When you read the suction temp on the gauges, it is actually the temp in the indoor evaporator. When you read the liquid line temp on the gauges, it is the actual temp inside the outdoor condenser. When you read actual line temps with you thermometer, that is the temp at the place you are taking it. The refrigerant is absorbing heat from the evaporator and returning it to the condenser. So your suction temp from your low side gauge will be lower than the actual line temp outside. You subtract the two and that is you superheat

On the liquid line, the refrigerant is giving off the heat in the outdoor condenser, so the temp on the high side gauge will be higher than what the actual liquid line temp is, so you subtract those two to get sub cooling.

Thats how you figure out what the actual sub cooling and super heat is. These two readings will tell a lot. And there are online calculators that will tell you what the target superheat should be depending on the inside wet bulb and outside ambient temps. If the unit has a expansion valve for a metering device, then the target sub cooling should be on the plate out on the condenser.

Watch Ac service tech on you tube, he explains it very well.

 

[FMB4]

I'd forget about testing pressures (unless you're willing to at least complete a beginner's HVAC course (your local Jr. college might offer such a course or courses). Just perform the common DIY HVAC maintenance by cleaning the system, checking for problems (fan bearing noise, duct issues, etc) and testing the output temps. Just my opinion.

 

[PoorUB]

I agree with the answers to your "What does that mean?" question.

Like I said, it is more than just checking pressures.

Your time will probably be spent better washing the outdoor coils and making sure air filters get changed. Blowing out condensate raps and the like. Leave the critical testing to a tech. And make some effort to find a good one.

 

[P0234]

Mastercool gauges on the way. Have been playing with the Emerson Check Charge app, seems pretty nice. Also found the Danfoss troubleshooter. Thanks to those providing help.

 

[LS6 Tommy]

Agree with leak checking Schrader valves after removing gauges. I don't attach gauges as part of a general operation check unless there's some specific indication that pressures should be checked. Reason being the propensity of Schrader valves to leak when messed with.

X2. I don't even use a manifold anymore unless I'm charging, recovering or evacuating. I use Testo stuff, especially the wireless pressure sensors for ops checks. Almost zero loss when I use them in conjunction with EZ Turn low loss adapters.

Tommy

 

[Jim greengo]

410a mini splits are 5/16. Condensers on standard 410a systems are 1/4, at least the ones that I have attached to

I haven't seen a 1/4" lineset used on a new conventional split system install in years,especially not on a 410a system.
Unless you're talking about just tying back into something really old.

 

[Terry D]

I haven't seen a 1/4" lineset used on a new conventional split system install in years,especially not on a 410a system.
Unless you're talking about just tying back into something really old.

Talking about the size of the Schrader valve connections, not the size of the line

 

[Jim greengo]

Oh,I've never seen them according to size.
My bad.

 

[metlmunchr]

Actually, it's the size of the service port connections. 1/4" OD flare is common across split systems from the days of R-12 to the current 410A, with the exception of mini splits which are 5/16" OD flare.