Correct Charge Verse Sight Glass Bubbles

[sageoldmann]

My home AC is correctly charged with R-22. It has a TEV. Even though the system is fully charged (68 PSI suction) according to the tech, I have a lot of bubbles in the sight glass right outside the condenser. After reading some articles it appears that with a TEV you can't have any bubbles in the liquid line...that it has to be a solid column of liquid to the TEV? Should I have more R-22 added to my system or leave it at 68 PSI suction and ignor the bubbles? Does 68PSI sound right?

[Graham]

My rule of thumb at our ambient temperatures is charge to 0 Degree C (suction at comp)for R22 air con. You seem to be running a bit hot.

[The Viking]

Some bubbles is OK.
A constant stream (or tree) of bubbles is not OK.

Pressures in themselves are meaningless, you need to look at them in relationship to temperatures.

As an enduser, the best thing you can do is to measure the temperature difference across the indoor unit. It should be at least 10 degrees Celsius (If you take a reading just after the unit been serviced and are known to operate 100%, you can refer back to this later on.)

If your unit is short of refrigerant, then you are likely to see ice forming on the indoor unit's coil. This should not happen on a correctly running A/C unit.

[Billy Ray]

sageoldmann,

If your system does not have a liquid receiver (vessel between condenser & liquid line) then ignore what is going on inside the sightglass!!

The only good purpose its serves is as a moisture indicator.

Generally, a system without a receiver should not have a sightglass as the information its gives you is misleading.

Billy Ray

[philfridge]

Sounds like the pressures are a bit high and i would not add anymore gas at 68 psi system is not short of gas. Bubbles in the sightglass just mean the t.e.v is opening and closing this is normal behaviour.

[nike123]

Sounds like the pressures are a bit high and i would not add anymore gas at 68 psi system is not short of gas. Bubbles in the sightglass just mean the t.e.v is opening and closing this is normal behaviour.

If temperature in ambient is 80°F, then that pressure is slightly low. You could not judge charge by only pressures readings.

[sageoldmann]

Please forgive my lack of technical knowledge. I'll add this information based upon these responses. There is a "muffler" right off of the compressor on the liquid line. I don't know if this is the "receiver" that was mentioned. Then it runs through the condenser and then goes through a "dryer" ,then to the sight glass. The outside air was 82 degrees and the air temp right off of the evaporator was 53 degrees. There were significant bubbles in the sight glass. The suction line was sweating right before the condenser. So who is right? Am I running high or low?

[philfridge]

If temperature in ambient is 80°F, then that pressure is slightly low. You could not judge charge by only pressures readings.

I am not there nor are you but can tell you 68 psi on an r22 system is fine

[nike123]

Please forgive my lack of technical knowledge. I'll add this information based upon these responses. There is a "muffler" right off of the compressor on the liquid line. I don't know if this is the "receiver" that was mentioned. Then it runs through the condenser and then goes through a "dryer" ,then to the sight glass. The outside air was 82 degrees and the air temp right off of the evaporator was 53 degrees. There were significant bubbles in the sight glass. The suction line was sweating right before the condenser. So who is right? Am I running high or low?

By this, you don't have receiver.
What is evaporator air in temperature?

[nike123]

I am not there nor are you but can tell you 68 psi on an r22 system is fine

I can tell you only (by my experience), that pressure reading, without any other, means nothing (except, that gas is present in system)!

[sageoldmann]

The air into the evaporator was 73 degrees.

[philfridge]

I can tell you only (by my experience), that pressure reading, without any other, means nothing (except, that gas is present in system)!

I can tell you by all the information supplied that the system is not short of gas

[nike123]

The air into the evaporator was 73 degrees.

Is your fan is at max sped (if you have more then one speed)?

[sageoldmann]

Yes the blower is at full speed and the air filter is new.

[TRASH101]

Hello sageoldman

What temp is the liquid line?

What condition is the condenser coil in?

Is the condenser fan running properly?

Is there a chance of air short cycling at the condenser?

Are the "significant bubbles" there all the time?

[sageoldmann]

I don't know the temp of the liquid line.
Condenser fan runs fine.
The coil is clean with good air flow. The compressor does not short cycle.
The bubbles are there all the time with no deviation of volume.

[TRASH101]

If the condenser has a manually set head pressure controller the condensing temp might be set too high. The liquid temp. is a good indicator.

Exactly where is the TEV in relation to the sight glass, evap, and drier?

Whats the exact temp. directly after the TEV and directly after the evap (i.e. the superheat)?

Is the liquid line insulated?

[sageoldmann]

OK you are starting to lose me here. I'm just a consumer not a HVAC tech. I can only provide this information for you. The TEV is at the evaporator, 15 feet from the sight glass. The dryer is inside the condenser unit, 2 feet before the sight glass. The liquid line is not insulated. I have no idea what superheat is and have no way to measure the temp of the line before and after the evaporator.

[TRASH101]

sorry about that

you have a good temp differential across your ahu the rest of the system is unlikely to be too far out and since you show such an interest next time you get a tech out to your house ask him to show you whats what. Im sure he wouldnt mind if you put a cold beer in his hand.

[sageoldmann]

Sounds like a plan!

[nadeem]

Please vaccum the system and recharge. I hope your problem would be solved.

[Thana]

Sounds a little high 68psi but remember pressure and temperature are related, so high ambient or heat loads in the room can all have an effect. Some bubbles is ok a sight glass is only an indication! this is the expansion valve opening and closing. My advise would be not to be technical..(I take it your not a Techie) check to see either by feel or measuring the temperature right at the compressor, this needs to be cool to keep the motor windings cool to stop them burning out, if this is cool or cold at 68psi..you have a 10 degree cooling effect inside at the evaporator then sounds like your not far of the mark..My advise to you would be Keep your condenser clean and filter, and keep an eye out for oil patches around any joints flares etc..Hope this helps...

[wilks]

I can tell you by all the information supplied that the system is not short of gas

phil he hasnt said that hes checked condenser and or the fan motor or anything or even evap coil condition.so the pressure hes saying is pontless. 68psi seems a bit high to me but this could be because of numerous factors , were just told he has bubbles and his suction is 68 psi . that info on its own is useless realy

[sageoldmann]

I did mention that the condenser fan was OK, the condenser is clean with good air flow. The evaporator was new last year and coils are very clean. Filter is clean and blower is set on high speed. Suction line is cool and sweating at the compressor.

I'm confused as to why you think 68 psi suction is high? With R-22 doesn't that make the evaporator temperature around 40 degrees? Should it be lower for an AC unit?

[philfridge]

phil he hasnt said that hes checked condenser and or the fan motor or anything or even evap coil condition.so the pressure hes saying is pontless. 68psi seems a bit high to me but this could be because of numerous factors , were just told he has bubbles and his suction is 68 psi . that info on its own is useless realy

Wilks please read all the posts properly before commenting these points have been checked already !!

[nevgee]

A lot of fuss over some bubbles!
Is the unit cooling adequately?
If so ...leave it alone.

[sageoldmann]

It's all about the bottom line. Those bubbles may be costing me money by causing the unit to run longer. Prior to having the evaporator replaced last year due to a big leak I had no bubbles, and air coming off the evaporator below 50 degrees all the time. The unit cycled normally. Now the air is between 53 and 56 degrees and the unit runs longer. Is it adequate? Maybe. But it's not efficient. The whole point of my question is whether the tech didn't put enough gas in the system to give me my cold temperatures and efficient operation again. The bubbles suggest that he didn't charge it properly compared to what I had before. I'm not talking about a few bubbles or normal opening and closing of the TEV. It's a constant stream of fizzing bubbles. Seems odd to me that when I didn't have them the unit was more efficient and cooler. I'm just trying to find out if there is a chance I'm short on the charge.

[Peter_1]

sageoldmann,

If your system does not have a liquid receiver (vessel between condenser & liquid line) then ignore what is going on inside the sightglass!!

The only good purpose its serves is as a moisture indicator.

Generally, a system without a receiver should not have a sightglass as the information its gives you is misleading.

Billy Ray

Very good comment Billy

[frank14]

Hi there

A bit late but I will add my two cents worth anyway. You need to get more info to actually make a diagnosis. Either beg borrow some gauges, a thermometer with a thermocouple type sensor and an ampmeter or get a tech there.

Measure low side pressure, high side pressure, temp of air in and out of evap and condenser, temp of line exiting compressor, exiting condenser and exiting evap, take volt and amp readings of fans and compressor. If you post those, you will get a diagnosis

Regards

[frank14]

A bit late, but will add my two cents anyway.

You need to get more info to actually make a diagnosis. I would get another tech there or beg/borrow the following: some gauges, a thermometer with a thermocouple type sensor, a volt/ampmeter.

Take the following readings. Low side presure,high side pressure, temp of air in and out of both evap and condenser, temp of line exiting compressor, exiting condenser and exiting evap. Take volt and amp readings of all fans and compressor compared to nameplate info.

If you post those, you will get a proper diagnosis.

regards

[Andy]

Please forgive my lack of technical knowledge. I'll add this information based upon these responses. There is a "muffler" right off of the compressor on the liquid line. I don't know if this is the "receiver" that was mentioned. Then it runs through the condenser and then goes through a "dryer" ,then to the sight glass. The outside air was 82 degrees and the air temp right off of the evaporator was 53 degrees. There were significant bubbles in the sight glass. The suction line was sweating right before the condenser. So who is right? Am I running high or low?

Hi Sageoldmann

Is the condenser on the outdoor unit clean, this would cause you symtoms.

Kind Regards Andy

[Larry2]

With a TXV, the system should be charged by measuring subcooling, not by looking a bubbles. Superheat should also be checked to rule out problems with the air flow or the valve. Still, I put a sight glass in my system. It seems reassuring, somehow. Bubbles are normal whle the TXV reaches equilibrium.

[ehowley]

Sageoldmann

I agree with Frank14. We need more info to properly diagnose whether it is charged properly. Pressures alone do not tell the whole story. And yes, at times you can be charged properly and still have bubbles in the glass.

High side Pressure-
Sat temp-
Liquid line temp-

Lo Side Press-
Sat temp-
Suction Line temp-

Return Air Temp wb-
Return Air Temp db-

Supply Air Temp wb-
Supply Air Temp db-

Airflow - cfm-
Outdoor Air Temp-
Condenser Leaving Air Temp-

This may seem a bit much, but is very important in system diagnosis and we haven't gotten to the electrical end of it yet