Central air recharge diy?

[antonmnster]

Now don't judge, but bought a 28oz can of 410a off ebay. Hooked up my gauges, which don't have the pressure/temp values for 410a, but they do accurately measure pressure, right?

Found a disgusting amount of cottonwood junk in the condenser. Seemed beforehand like the fan was blowing well, but I was amazed at how much was packed in there. Spent an hour taking the cabinet apart and vacuuming it up. Put it back together, hooked up the gauges, stuck a thermometer along the vapor line under the insulation.

High side pressure was stable at around 275. Low side about 110. The system maintained these pressures pretty evenly while adding all 28 oz in the can over 45 minutes. Ambient temp was about 73. Vent temp is now 59. Vapor line temp is way up there at about 65.

Please don't fry me. I'm assuming that I overcharged the system. But I'm guessing that the compressor is weak - the high side should be higher and the low side lower.

Thoughts?

 

[KJSmith]

Thoughts?

Hire someone who knows what they are doing.

 

[Jethro_Bob]

Refrigerant is measured by weight not pressure. Did you at least pull a vacuum against the gauge set before connecting your can of 410a? Or did you push contaminants into the system?

 

[Skippy722]

Well your question grabbed my curiosity, and I went down a rabbit hole of home HVAC. Sub cooling, super cooling, there is math involved

In my incredibly unprofessional opinion, and assuming you already had some charge in the system, you definitely over charged it.

 

[HangFire]

HVAC is so hard professionals overcharged my system and left the indoor coil clogged, all because of some pressure readings "coming back too low". Then the professionals added a motor capacitor because of all the circuit breaker trips.

 

[Audios]

If the pressures havent changed much, you either over charged it, it still needs more of a charge, or the compressor is failing. The best thing to do is start over, evacuate it all and weight the charge. Recharge to spec and re check pressures and go from there. Last time i needed a blast it was about $200.

 

[alarmguy]

OMG,

We have a now 13 year old home. Second floor heat pump, main floor just AC.
At the time the house was built the builder installed Heil units and we were told that they were the new units that could be upgraded if need be in the future from the R22 to ____whatever it is with a valve change.

Ok, going back YEARS now, my main floor unit was NEVER cooling like I thought it should, low pressure side was never cold or even cool except in cool weather.
over the years, here and there, I HAD various AC guys check it out, they all said it was fully charged, showed the gauges to me ect. I even told one of them to replace the expansion valve and install a new dryer, (I used to own a grocery store and know a fair amount about this stuff.

They all said they didnt understand why the low side was so high and never wanted to put more r22 in it. One guy from a huge company said he was afraid, felt it was too high as it is, Some wanted to sell me a new unit, others thought the valves might have been burnt... whatever... all I know is the temp coming out of the air vents was only about 10 degrees cooler this going in.

Well, this year I finally said the h** with it, this will work or the thing will just burn up, got a hold of a 5lb container of r22, bought a set of gauges. I observed the correctly working second floor heat pump unit low side was around 75 or was it 90 (I forgot)

The main floor unit that NEVER worked right was around 55. I opened the valve on the Freon and filled her up! Until I was exactly at the same low pressure of the correctly working second floor unit (75 or 90) right away the low pressure side got cold, so this year, here we are months later in our 90+ summer (always) the air temp coming out of the vents is now about 18 degrees colder then the intake. The unit no longer runs constantly and cycles on and off like the second floor unit.
In fact I am really upset, all these years of the main floor unit running double time, never mind the electric, also the wear on the unit.

Question to all WHO KNOW, why have various Ref "techs" tell me it was fully charged and they were clueless as to what was going on? Sell me a new unit?
OR was our "newer" r22 to r --- whatever convertible units throwing them off not knowing they work at higher pressures?

This story maybe hard to believe but I am telling you, multiple people have looked at my system over the years, none wanted to put more freon in it and here I go, on my own, fill her up and the darn thing works freaking great and I really mean freaking great, been months now or 90 to 100 degree days, perfect.

 

[ethnix]

Tha
Originally Posted by KJSmith
Thoughts?

Hire someone who knows what they are doing.


Easier said than done. Since he appears to have some of the equipment and the desire to fix the issue, hopefully someone will be able to assist on here.

 

[Vern_in_IL]

YOU CANNOT GO BY THE PRESSURES. The only way to know you got the correct charge is a evac and recharge using a scale.

There are DIY kits on Ebay.

 

[KrisZ]

Originally Posted by Vern_in_IL
YOU CANNOT GO BY THE PRESSURES. The only way to know you got the correct charge is a evac and recharge using a scale.

There are DIY kits on Ebay.


Why would you look only at pressures?

When you look at the pressures, plus vent temps, plus low side temperature, you can determine if correct amount of charge is in.
You have to look at how the whole system reacts when you start adding the redrigerant, not just pressures.

 

[KJSmith]

Originally Posted by ethnix
Tha
Originally Posted by KJSmith
Thoughts?

Hire someone who knows what they are doing.


Easier said than done. Since he appears to have some of the equipment and the desire to fix the issue, hopefully someone will be able to assist on here.


Just as a start.
410a is an isotope. (A mixture of freons.)
Generally one Freon tends to leak out at a higher rate than the other.
Depending on how low the system was, a complete removal and recharge may have been called for.

Yes, you go by pressures, you just convert the pressure to a temperature using a PTE chart.
But you still have to understand the relation of it all.
Outside air and return air play a big part.

Very few people weigh in Freon in a field built system.
You would need to know the exact length of line sets, temperatures ect.

Much easier to use super cooling and or sub cooling.


Again, hire a qualified person to do this work.


It is not a DIY homeowner project.

 

[kschachn]

I think you mean azeotrope, not isotope. And it's not quite an azeotrope but close.

 

[ethnix]

AC Service Tech has this video on checking refrigerant charge.

 

[HangFire]

Originally Posted by alarmguy
OMG,

We have a now 13 year old home. Second floor heat pump, main floor just AC.
At the time the house was built the builder installed Heil units and we were told that they were the new units that could be upgraded if need be in the future from the R22 to ____whatever it is with a valve change.

Ok, going back YEARS now, my main floor unit was NEVER cooling like I thought it should, low pressure side was never cold or even cool except in cool weather.
over the years, here and there, I HAD various AC guys check it out, they all said it was fully charged, showed the gauges to me ect. I even told one of them to replace the expansion valve and install a new dryer, (I used to own a grocery store and know a fair amount about this stuff.

They all said they didnt understand why the low side was so high and never wanted to put more r22 in it. One guy from a huge company said he was afraid, felt it was too high as it is, Some wanted to sell me a new unit, others thought the valves might have been burnt... whatever... all I know is the temp coming out of the air vents was only about 10 degrees cooler this going in.

Well, this year I finally said the h** with it, this will work or the thing will just burn up, got a hold of a 5lb container of r22, bought a set of gauges. I observed the correctly working second floor heat pump unit low side was around 75 or was it 90 (I forgot)

The main floor unit that NEVER worked right was around 55. I opened the valve on the Freon and filled her up! Until I was exactly at the same low pressure of the correctly working second floor unit (75 or 90) right away the low pressure side got cold, so this year, here we are months later in our 90+ summer (always) the air temp coming out of the vents is now about 18 degrees colder then the intake. The unit no longer runs constantly and cycles on and off like the second floor unit.
In fact I am really upset, all these years of the main floor unit running double time, never mind the electric, also the wear on the unit.

Question to all WHO KNOW, why have various Ref "techs" tell me it was fully charged and they were clueless as to what was going on? Sell me a new unit?
OR was our "newer" r22 to r --- whatever convertible units throwing them off not knowing they work at higher pressures?

This story maybe hard to believe but I am telling you, multiple people have looked at my system over the years, none wanted to put more freon in it and here I go, on my own, fill her up and the darn thing works freaking great and I really mean freaking great, been months now or 90 to 100 degree days, perfect.

The proper way to check A/C is with 4 gauges and some serious calculations. So almost every service tech uses 2 gauges and some rules of thumb... which used to work OK, most of the time, on systems before TXV valves, but no longer.