Anyone have knowledge on home A/C units?

[Haertig]

Does anyone here have home A/C maintenance/repair knowledge?

I'm trying to decide if we need a service call. On two occasions this year we have noticed that the outside copper going to the compressor is frosted over. I do not know if this indicates that the condenser inside is also frozen over. I have not taken the time to open up the inside unit to check for freezing (it's a little hard to get to). But since the house appears to be staying cool inside, my assumption is that it is not frozen. But maybe we've just gotten lucky and things have naturally started cooling off outside right at the same time our A/C has decided to freeze and not work. The condenser has frozen before (years ago), and the A/C tech adjusted the amount of coolant to fix that. IIRC, there seems to be a sweet spot for coolant level that makes the A/C work without freezing over.

When we noticed that the outside line was frosted, the inside of the house was still cool, right at the temperature we had the thermostat set to in one instance, and a single degree over in the other instance. Our setting is 72 degrees. Being in Colorado, we do not have gigantic A/C units like in the south. Ours is a 3 ton unit I believe, and our house is 2100 sq feet with a half basement in addition to that. If it's hot outside, our A/C has never been able to take the inside temperature down, but it can maintain it. e.g., if it's 92 outside, and we are set to 72 inside - and we turned the A/C on before it hit 72 inside - then the house will stay at 72. However, if we let the house climb to 74 before turning on the A/C when it's hot out, the best it can do is keep the house from rising further above 74, it won't bring it down to 72 until it cools off significantly outside. The temp coming our of our vents varies between 58 and 62 degrees (it's still in this range when the outside pipe is frosted over). This kind of follows the outside temp. Right now, it is 95 outside (I just took an accurate air temp reading at the A/C compressor location). And our vent temp is 61.5 degrees, with an airflow of 8 to 12 mph depending on where on the vent I am measuring (average is 9 mph). I am not equipped to measure the air volume, just the velocity. One other thing - we are very low humidity here. In the mornings we may rise to 30%, but by afternoon we're more typically 12-15%. Pretty dry most of the time.

OK. That's probably a lot of "we didn't need to know that" information about my A/C and local climate. Do I need a service call for the outside pipe occasionally frosting over assuming the A/C is still cooling the house appropriately? Obviously, if the house is no longer cooling then we need a service call. But if we do have a problem now, I'd rather catch and fix it before we're sitting inside in 80 degree heat wondering why we didn't call the A/C tech sooner!

Frosted:

Not frosted:

 

[UrbanHunter]

I don't know much about HVAC, I am betting that the line run between the inside unit and the compressor is relatively short and that line would normally be cool, if the outside humidity is relatively high, frost may form on the line. Just look at your car's AC lines after you have been running it a while and you will see something similar.

If your AC is not pulling down the house temperature, I would check to make sure the filter and evaporator coils are clean. I would also check to make sure the condensate lines are clear (condensate is the water that forms when warm wet air is cooled by the evaporator coils)from the drip tray, to the pump, to the drain. These are things you should be doing every 6 months as maintenance anyway.

If everything looks okay and you are not happy with the cooling, I would call the AC guy before it gets hot and he gets really busy. Before you make that call I would brace myself. My Unit got low on refrigerant this year and I called out the guy, $175 just to show up, then $125 an hour, and then he added refrigerant at $125 a pound. So my simple ac service call cost me right at $1000. I was set back because I was expecting half that....

 

[Haertig]

I am betting that the line run between the inside unit and the compressor

It's about 30 feet, and insulated with that round, black, foam stuff.

 

[UrbanHunter]

It's about 30 feet, and insulated with that round, black, foam stuff.

Frost forms when the line or coils are made cold as the refrigerant is making the transition from a liquid to a gas, the frost would indicate that the refrigerant is still evaporating near the end of the line run, so I would doubt that you are low (or very low) on refrigerant. That is why I suggested making sure your filter and evaporator coils are clean, normally the coils allow heat to be pulled out of the air and into the evaporating refrigerant inside the coils, dirt and lent will act as an insulator and reduce heat transfer. Usually, all the refrigerant would evaporate inside the evaporator coils and you would not see the frost outside the house. Normally that line would be cool (45-70F) but not at the 32F required to make frost....

But as I said I don't know much about HVAC

 

[backlash]

My AC unit did that occasionally.
That black foam insulation is on there to stop it from frosting over.
Repair the foam so all of the copper line is covered and you should be OK.

 

[LadyLocust]

Calling @Acdoctor (We probably need to set up a 'tip jar' for you)

 

[INresponse]

Does anyone here have home A/C maintenance/repair knowledge?

I'm trying to decide if we need a service call. On two occasions this year we have noticed that the outside copper going to the compressor is frosted over.

Frosted:
View attachment 87931

That is the line with the cold feed to the unit in the house. It should be covered in foam insulation and all ends and connections of the foam should be taped. Hope Depot sells the foam tubes, that have a slit down them lengthwise so it goes over the pipe, and they should be on the aisle with the air filters or with the plumbing pipes. They are usually inside cardboard display boxes. You will need to know the diameter of your pipe, probably 1/2".

There is nothing wrong with your AC system, that lines gets cold, moisture condensates on the line and then freezes causing the frost. The only thing wrong is the lack of insulation. Basically you ae wasting a bit of the cooling effect so once you insulate it you will be good, and saving a few cents each time the unit cycles.

 

[Acdoctor]

The insulated line should sweat but it should not have frost on it unless the system is low on Freon, reduced air flow, possibly a dirty filter, dirty evaporator coil or thermostat is set too low.
if you have frost on the lines it may need to have a preventative maintenance done on it. I’m not sure about your area but around here that will run you around $85.00, also make sure the condenser coil is clean of debris

 

[Neb]

The insulated line should sweat but it should not have frost on it unless the system is low on Freon, reduced air flow, possibly a dirty filter, dirty evaporator coil or thermostat is set too low.
if you have frost on the lines it may need to have a preventative maintenance done on it. I’m not sure about your area but around here that will run you around $85.00, also make sure the condenser coil is clean of debris

Ben

 

[Weedygarden]

@Haertig All of my neighbors and I have evaporative coolers. Cheaper to run, keeps the air a little humidity in this desert area.

 

[Supervisor42]

Ben

I was waiting for him to chime in, I was going to say exactly the same thing, but I'm not a pro and didn't want it swept away.
I mentioned me 'brushing' our indoor coil just a couple weeks ago.

 

[Neb]

@Haertig All of my neighbors and I have evaporative coolers. Cheaper to run, keeps the air a little humidity in this desert area.

Swamp coolers are a no go here.

We pick up a lake effect with air coming down across lake Erie. That is a blessing that George Washington described as a land of milk and honey because God keeps the garden watered.

But a swamp cooler only makes high temps and humidity higher humidity with slightly lower temps. Better to go without them and sweat to control body temp.

Ben

 

[Weedygarden]

Swamp coolers are a no go here.

We pick up a lake effect with air coming down across lake Erie. That is a blessing that George Washington described as a land of milk and honey because God keeps the garden watered.

But a swamp cooler only makes high temps and humidity higher humidity with slightly lower temps. Better to go without them and sweat to control body temp.

Ben

I know people who move to Colorado from the East Coast, and close to the lakes think we are crazy when they see all the swamp coolers here. They have no idea just how effective they are. When you are used to being in heat and humidity, the idea of putting humidity in the air to cool you off sounds like lunacy. But it works in arid places, like Colorado, Nevada, Utah, Arizona, New Mexico.

 

[Supervisor42]

Swamp coolers are a no go here.

We pick up a lake effect with air coming down across lake Erie. That is a blessing that George Washington described as a land of milk and honey because God keeps the garden watered.

But a swamp cooler only makes high temps and humidity higher humidity with slightly lower temps. Better to go without them and sweat to control body temp.

Ben

Ditto.
They were in every manufacturing facility up on the hills where I was in Bama.
They would be awesome out west like where @Pearl is with her 17% humidity.
I have never seen one down here because when we get stuck above 80% for weeks, they do nothing. Evaporate what?
(it's normal today...74%)

Now back to Dave's A/C: get some gas put in it and clean the lint off the indoor coil.

 

[Haertig]

Thanks for all the replies. I knew there had to be people here who know a lot more than I do about this. And we do!

I know the filter is clean - just replaced that recently. We replace the filter often - I think too often - but the wife is fanatical about it. The coils (evaporator and condenser I guess they're called) we have cleaned professionally, but I has been two (three?) years since that was done. So overdue. I remember watching things being cleaned on one service call. The tech was telling me that what I was looking at (I don't know which "coil" it was) was like a million little razor blades in it's potential to slice your arms up, and you didn't want to bend/damage those little fins. Ever since that comment, I have had exactly zero desire to stick my arms in there. It doesn't cost much for an inspection and service if nothing is really wrong except things being dirty. The refrigerant is not cheap, but we've never needed much - just a little bit to top things off on rare occasions. Still, "a little bit" is not cheap.

I think I'll just call for service. It's been a while, so it's due, even if we weren't experiencing this frosting thing.

Although our A/C is cooling just fine, even with it's rare frosting, my son's A/C is not. So I'm going down to his house while he's at work later this week to meet the A/C guy we just scheduled for a service call. I'm afraid of what he's going to find at my son's place. I know that my son doesn't keep up with filters and cleaning the vents and air returns. I'll bet there are the equivalent of two sasquatch families of cat hair clogging everything up. Also, it's an older house that doesn't have ductwork sized for A/C, so the installation of the A/C 10 years ago was a compromise from the get-go. This should be an eye (and wallet) opener.

 

[Haertig]

Regarding swamp coolers - those do work very well here. We had one in the ambulance building back when I worked as a paramedic. It could really freeze the place out. All the cooling you could ever need. But it always felt damp inside. I'm thinking that whoever installed the unit might have put too large of a machine in place. It could easily over-cool, and over-humidifize.

Because of the high humidity they create, I've always wondered about potential mold growth. Normally, we never see mold here - its just too dry. Some people install swamp coolers like window A/C units. Others apparently hook them up into their ductwork. It is the latter method of installation that would worry me if indeed mold could be a problem. Maybe it's a non-issue in the dry climates where swamp coolers work.

 

[INresponse]

The insulated line should sweat but it should not have frost on it unless the system is low on Freon, reduced air flow, possibly a dirty filter, dirty evaporator coil or thermostat is set too low.
if you have frost on the lines it may need to have a preventative maintenance done on it. I’m not sure about your area but around here that will run you around $85.00, also make sure the condenser coil is clean of debris

@Acdoctor is correct, but I was thinking the AC had been running too long trying to cool off a warm house and that allowed enough time for the frost to form. I am not a professional by no means, but I used to help my friends do AC repairs and replacements several years back so that is where my memory was pulled from.

@Haertig, you will be the one who would know if it is possible the AC was running a long time trying to cool off a warm house. I am thinking more than 20 minute run times per cycle, depending on the humidity outside that time may vary. Not only does the AC have to cool the air inside it is removing the humidity in the air and hot wet air takes longer to cool with an AC than hot dry air because the humidity holds more heat than dry air. At least, as far as what I recall. It took forever to cool my parents house in Michigan when they waited until the evening to turn on the AC, and in Las Vegas with the same exterior temperature the house cooled off a lot faster.

 

[Haertig]

Update to this thread I started a month ago:

Our A/C ran fine for the last month since I started this thread. Then yesterday it decided "That's it. I am no longer going to cool. I am going to freeze up instead." So we called the A/C technician out. We were low on coolant (as expected). Our A/C is maybe 15 years old (?) and it uses the old R-22 refrigerant that I think has recently been banned from manufacture. Repair techs can evidently still use it though. The tech told me that his company will only refill an R-22 system once. Our system had been topped off with refrigerant once before, maybe five years ago, but that was by a different company. So we got refilled with R-22 today, and he also added something in with the coolant called "A/C Leak Freeze with Magic Frost". This stuff is supposed to (maybe/hopefully) seal any micro leaks you have in the system.

Other options we were given instead of Leak Freeze and Refrigerant Refill were (1) System testing to find the leak, and if found, replace problem parts and then refill. This option was estimated to be over twice as costly as the Leak Freeze. The other option was (2) Replace the A/C. You don't even want to know how much that would have cost! The good thing about the Leak Freeze is that if it doesn't work, the entire cost of trying that would be credited to any other repairs/replacements that are subsequently done. I saw zero downsides to at least trying the Leak Freeze, so that's the option I went with. Seeing as how it took five years for our refrigerant to drop from full to unit freezing up, it sounds like our leak is a very slow one, and a good candidate for the Leak Freeze to be able to handle.

Now our system is working great. Outside is 100 degrees. Inside was 80 degrees when the tech got here. After refilling the system (that took about 1 lb of R-22 I think the tech said), we are getting nice 56 degree air coming out of the vents. The tech said the temperature difference between 80 degrees inside and 56 degrees coming out of the vents was good. Apparently the difference between outside temp and vent temp is not as meaningful as the difference between inside temp and vent temp. It will take a few hours for our house to cool down to where we normally keep it. But it's already much much better in the downstairs (we have a tri-level, which I think are a bit of a pain to cool for A/C units).

Today's tech gave us a tip - the same tip that a tech from a different company had given us years before. He said, "Don't buy the expensive filters that are supposed to last for three months. Buy the 98 cent cheapies and change them every month." One, this is cheaper overall (those expensive filters can cost $20). And two, the expensive filters block airflow more than the cheapies, and that makes things much harder on your system. He said if you feel the need for better/finer filtration then there are other ways to achieve what you want than with a super filter, which just blocks your airflow anyway. I like recommendations that save me money while improving things over the more expensive options. He said, "These are just filters. Nothing magical here." He mentioned one lady who asked him what type of filter would take Covid out of the air. Like you're going to filter a virus out of your air, let alone using a furnace blower to do it. But I guess that illustrates there really is a market segment willing to buy those super expensive magic filters.

 

[Supervisor42]

Our A/C ran fine for the last month since I started this thread. Then yesterday it decided "That's it. I am no longer going to cool. I am going to freeze up instead." So we called the A/C technician out. We were low on coolant (as expected). Our A/C is maybe 15 years old (?) and it uses the old R-22 refrigerant that I think has recently been banned from manufacture. Repair techs can evidently still use it though. The tech told me that his company will only refill an R-22 system once.

Other options we were given instead of Leak Freeze and Refrigerant Refill were (1) System testing to find the leak, and if found, replace problem parts and then refill. This option was estimated to be over twice as costly as the Leak Freeze. The other option was (2) Replace the A/C. You don't even want to know how much that would have cost!

I will probably get in trouble for this, but oh well ...
Our system was about 20 years old when it started the "I'm low of coolant problem" in 2019.
We got it gassed up and it was good for 6 months... then we got it gassed up and it was good one month. The tech said the indoor coil was leaking everywhere.
FIL wanted to pinch pennies; I told them to change the entire system, both the inside and outside units.
Also changed it from a 3-ton to 3.5-ton. Best $7,500 we ever invested.
After you have recovered from passing-out, I will add...
So much has changed in recent years in the efficiency (SEER rating) of them, you have to look long term.
It cut our cooling costs in half and has more than halfway paid for itself by today.
In another 3 years, it will have been "free".
...Oh, did I mention that it runs flawlessly, and air blasts out of the vents?

 

[dademoss]

I will probably get in trouble for this, but oh well ...
Our system was about 20 years old when it started the "I'm low of coolant problem" in 2019.
We got it gassed up and it was good for 6 months... then we got it gassed up and it was good one month. The tech said the indoor coil was leaking everywhere.
FIL wanted to pinch pennies; I told them to change the entire system, both the inside and outside units.
Also changed it from a 3-ton to 3.5-ton. Best $7,500 we ever invested.
After you have recovered from passing-out, I will add...
So much has changed in recent years in the efficiency (SEER rating) of them, you have to look long term.
It cut our cooling costs in half and has more than halfway paid for itself by today.
In another 3 years, it will have been "free".
...Oh, did I mention that it runs flawlessly, and air blasts out of the vents?

I don't know how old our unit was, it was in place when we bought the house in 1991. 20 years later, it went tits up. We installed the highest SEER AC, and the most efficient NG furnace we could. Utility usage went to 50% of previous use. A big outlay, but it has paid for itself at least 3 times over so far.

 

[Neb]

I will probably get in trouble for this, but oh well ...
Our system was about 20 years old when it started the "I'm low of coolant problem" in 2019.
We got it gassed up and it was good for 6 months... then we got it gassed up and it was good one month. The tech said the indoor coil was leaking everywhere.
FIL wanted to pinch pennies; I told them to change the entire system, both the inside and outside units.
Also changed it from a 3-ton to 3.5-ton. Best $7,500 we ever invested.
After you have recovered from passing-out, I will add...
So much has changed in recent years in the efficiency (SEER rating) of them, you have to look long term.
It cut our cooling costs in half and has more than halfway paid for itself by today.
In another 3 years, it will have been "free".
...Oh, did I mention that it runs flawlessly, and air blasts out of the vents?

Ok.

This story is just too good not to share.

When bought my place it had a big old furnace that took up 1/3 of one basement room and was older than me. The Princess was working for a gas company that entered a consortium with York and Briggs and Stratton to build natural gas heat pumps. So she got 2 refunds on the deal.

The new duct work required moving water heater and main water lines in the house. I purchased 3/4 lines instead of the standard to eliminate issues with shower temp going wonky if the washing machine was in use.

So I upgraded from heat only to HVAC and upgraded my water lines for $3000.

But it didn't end there!

There was a design flaw in the transmission and York cut their losses and elected to replace all units that failed under warranty with traditional gas furnace and AC. My engine failed 5 years in. Everything got replaced at 0 cost.

Aside from an induction fan, an ignitor and a sensor I had to replace it is still working fine.

Best $3000 I ever spent (not counting the engagement ring).

Ben

 

[JamesY]

im an hvac technician. if your unit is frosting up there are 2 reasons. low on refrigerant or low airflow. could be dirty filters, dirty evaporator coil, or you could have a refrigerant leak and its low on freon. eitherway you need a tech to come diagnose and fix it.

 

[Haertig]

Best $7,500 we ever invested.

They don't come so cheap here. My quote for replacement was over $19,000. Granted, this was from an expensive outfit. They are known for high prices, but also for exquisite customer service and extreme competence and reliability. That comes at a price. And it's a hefty one. But their quote seems quite high to me, even for an expensive place. We would definitely shop around before putting out that kind of money. The tech said that A/C installations have gone up almost 70% since covid and supply chain issues messed everything up starting in 2020.

In addition to that, there was unspecified potential "electrical work". I don't know what that would be. The current unit sits on its own 60 amp circuit that was installed at the same time the A/C was (I think that was 15-20 years ago, but my memory is so bad regarding these things). The electrical was done by a certified electrician, to code, with the pull-out shut off right next to the A/C unit and all that. Unless codes have changed regarding /'C electrical in the last 15 years, I can't image what electrical work would be needed (other than connecting the new unit to the existing wiring).

 

[Neb]

They don't come so cheap here. My quote for replacement was over $19,000. Granted, this was from an expensive outfit. They are known for high prices, but also for exquisite customer service and extreme competence and reliability. That comes at a price. And it's a hefty one. But their quote seems quite high to me, even for an expensive place. We would definitely shop around before putting out that kind of money. The tech said that A/C installations have gone up almost 70% since covid and supply chain issues messed everything up starting in 2020.

In addition to that, there was unspecified potential "electrical work". I don't know what that would be. The current unit sits on its own 60 amp circuit that was installed at the same time the A/C was (I think that was 15-20 years ago, but my memory is so bad regarding these things). The electrical was done by a certified electrician, to code, with the pull-out shut off right next to the A/C unit and all that. Unless codes have changed regarding /'C electrical in the last 15 years, I can't image what electrical work would be needed (other than connecting the new unit to the existing wiring).

Curious

Was that quote before or after inflation ?

I was used to a gas water heater running about $400 but the one we purchased for the remodel place was $800.

Ben

 

[JamesY]

They don't come so cheap here. My quote for replacement was over $19,000. Granted, this was from an expensive outfit. They are known for high prices, but also for exquisite customer service and extreme competence and reliability. That comes at a price. And it's a hefty one. But their quote seems quite high to me, even for an expensive place. We would definitely shop around before putting out that kind of money. The tech said that A/C installations have gone up almost 70% since covid and supply chain issues messed everything up starting in 2020.

In addition to that, there was unspecified potential "electrical work". I don't know what that would be. The current unit sits on its own 60 amp circuit that was installed at the same time the A/C was (I think that was 15-20 years ago, but my memory is so bad regarding these things). The electrical was done by a certified electrician, to code, with the pull-out shut off right next to the A/C unit and all that. Unless codes have changed regarding /'C electrical in the last 15 years, I can't image what electrical work would be needed (other than connecting the new unit to the existing wiring).

electrical codes change every couple years but that doesnt explain it.

ask them to elaborate.


19k is pretty high unless its a 20 seer unit that needs alot of ductwork repairs. the equipment prices are the same all over the country. the only difference is wages/cost of living. if your in a big city labor will be much more than a small town.

 

[JamesY]

Curious

Was that quote before or after inflation ?

I was used to a gas water heater running about $400 but the one we purchased for the remodel place was $800.

Ben

water heaters are getting ridiculous. so is pvc pipe. 4 inch has tripled in price and fittings that used to be $10 are now $50!.....and they just keep asking us to build/plumb more houses.

 

[Haertig]

Was that quote before or after inflation ?

It was yesterday. So after the existing inflation, but before even more inflation that is yet to come!

I mentioned the quote was from an "expensive place". In the past this "expensive place" had tended to charge about 1-1/2 times what a "normal place" would charge, or maybe even a tad more. Ballpark.

When I heard their quote for $19k, I was thinking to myself, "I should be able to get an equivalent installation from someone else for about $12k to $14k". That still ain't cheap! This is for a 3-ton unit which is a typical size for around here (unlike the mondo systems in the South), so it's not a huge A/C system at all.

We don't live "in the city", but we live in "the Denver metro area". We are more suburb in feel, but we're actually a separate town. All the towns run together here, with a bit of open space between them when you get out to the farther peripheral area where we are. Bit we pay the same prices as people "in the city", other than local tax rates.

 

[Supervisor42]

It was yesterday. So after the existing inflation, but before even more inflation that is yet to come!
I mentioned the quote was from an "expensive place". In the past this "expensive place" had tended to charge about 1-1/2 times what a "normal place" would charge, or maybe even a tad more. Ballpark.

When I heard their quote for $19k,

...Sounds like Rheemer guys to me.

Edit: Heck even if you got "Rheem'd", both parts of a complete 3.5 ton system is only $3,290.
https://www.nationalairwarehouse.com/3-5-ton-rheem-14-seer-r410a-air-conditioner-split-system-classic-series.html

(this system isn't near as good as others that are a lot less. Not recommended.)

 

[INresponse]

What the heck, I will chime in with my cost for a complete new install of the entire HVAC system. This was about 4 years ago but for a 4 ton natural gas system it was $8000.00 installed.
As for replacing an existing system I used to help my friend with his side jobs of R&R old units and it really isn't that hard for someone who knows what they are doing. I think the quote for $20k is very high. Did they give you a written quote with the breakdown for the new unit (manufacturer and part numbers) and any new parts or ducting or plumbing they will be including in the job? If so search up the retail price of those parts and that will let you know if they are over charging for the parts or if they are over charging for the labor. Just a suggestion.

 

[zoomzoom]

At my main house, we replaced our entire system (5-ton heat pump & electric furnace/air handler). It's a Bosch so it's a high-end unit. The unit + installation was about $9500. With the A/C running and 90 degrees outside, the farthest air duct still blows temps below 50 degrees.

A couple months ago, we replaced the A-coil in our condo's Trane unit at a cost of $3000. They're total crap (look up "Trane evaporator coil" and you'll find hundreds of complaints). When it fails again, the Trane is gone and I'll never buy another. BTW, Trane equivalents have the same issue.