Air Conditioning - System not cooling. Weird problem to me!

Hello,

I have a 10 year old central A/C, split system (heat pump). It is a 3.5 ton unit. The problem is a typical one. It is just not cooling like it should. This seems like a weird problem to me but it could be just as simple as low refrigerant. I don't know, so bear with me if you would.

So, here is what I can tell you about what I have found out.

EVAPORATOR SIDE (A/C set to cooling)

With the system running, the evaporator coil line (larger diameter) is just slightly better/cooler than ambient temperature. The inlet to the coil (small line) is not hot to the touch. When I turn the unit off, I can here what sounds like freon flowing inside the line for a couple of seconds and then it stops.
The evaporator air handler fan is working and blowing air (this is easy to tell). I then took the side panel off and looked at the down side of the evaporative coil. The bottom rows of the coil were wet with condensation and there is condensation in the tray. I also heard water draining a couple of times when I turned the unit off. The coil on the inlet side of the evaporator is clean and clear. The filter is clean and changed monthly.


CONDENSOR UNIT OUTSIDE (A/C set to cooling)

The condensor coil is clean and clear. The condensor fan is running and works good. I hooked up the pressure gages to check the pressures. The compressor is working, 63 psi low and 230 psi high side. It has been holding this pressure since two days ago when R22 was added. Before refrigerant was added, the pressure was, 40 psi and 200 psi. The unit still didn’t cool after the R22 was added. I was told the typical pressure are suppose to be between 60-80 psi low side and 275 psi high side.Are these pressures good on refrigerant? Does the system need more R22?

ADDITIONAL INFORMATION

I don’t know if this info below is relevant, but I will put it out there if it helps diagnose the problem with my system.

When I first turned”ON” the system to check the pressures (at the condensor unit outside) , the line from the accumulator to the compressor was cold for about 2 minutes and then went ambient. The bottom of the accumulator had a clearly defined condensation line about 3 inches from the bottom and was cold. The bottom of the accumulator then went ambient about 4 minutes later.

At the bottom of the condensor coil is a switch. I can’t get a good look at it. It is behind the compressor blocking my view, but it looks like a temperature switch from the way it is clamped onto the 1/4 copper line. It has two wires coming out of it that go to a electronic circuit board where the terminals are labeled “R” and “DFT”

The 1/ 4 inch copper lines between the compressor to the condensor coil are hot to the touch (8 quarter inch lines going into the coil from a manifold) the small 1/ 8 inch copper lines from the condensor coil that collect in a manifold are ambient to the touch.

There is a pressure switch on the small diameter copper line next to the inlet valve on line going from the condensor unit outside to the evaporator coil inside.

The large (3/4 diameter) copper line from the reversing valve going to the condenser is hot to the touch. The inlet line to the rev. valve from the compressor is hot to the touch. The line coming back from the evaporator (larger diameter) into the rev valve is ambient. The line from the rev valve into the accumulator and then into the compressor is ambient. The smaller line from the condensor to the evaporator is ambient to the touch.


HEAT PUMP (turned Heat “ON” to check it out)

It is about 100 degrees outside at 9:30 am. I live in the Desert southwest. I disconnected the pressure gages and turned “ON” the heat. I then hooked up the high pressure gage only. Not knowing what pressures I would get, I didn’t want to over range the low pressure gage. With the heat “ON”, the larger diameter line was 250 psi and the smaller diameter line was 275 psi. This doesn’t make sense to me. If I understand correctly, the large diameter copper line should be at a higher pressure if it is the supply line to the evaporator when the heat is turned “ON”.

The line (larger diameter) at the evaporator is hot to the touch and I was getting warm air from the vents. So, the heat pump part seems to be working good ( Wish it was winter :) ) The smaller diamter line at the evaporator coil is just warm after it comes out of the coil.

Anyway, that is all the info I can give you guys that I have checked out and hope someone can help me diagnose the problem on the 10 year old unit. Is it time to call a real professional? Does it just need more refrigerant?

Thanks for your patience in reading this long post.

Robert

Hello again,

This is a follow up with more information.

Well, now that the system is in the shade, I went out and took another look at it after reading a previous post about the reversing valve.

I read a previous post on the forum about the reversing valve and it got me thinking whether that might be the problem with my system. I went and checked out the reversing valve solenoid. The resistance on the solenoid coil measured 20 ohms and the voltage measured 25 volts when energized. The solenoid is slightly magnetic when energized. I checked this with a screwdriver tip. I don’t know how strong this magnetic field should be, but I think the solenoid is OK.
So, I’m thinking that the reversing valve body is not operating properly, but I could be wrong. I am no A/C technician.


So, if my problem turns out to be the reversing valve, how costly will it be to have it replaced to get my system going again? Parts and labor $$$?... and cold beer! :)

Below is the info on the reversing valve and solenoid if it helps.
Reversing valve numbers

B1227310
U10-314081-1GD
9419 10
500 M.O.P
used with L28,
L29, L30, or L31


The numbers on the solenoid coil are:
30524122046-001
24V 50/60HZ 6/4W
N-3072


Thanks again for reading my post. ( I hope you don't mind) :)

Robert

You have to be EPA to work with the gauges and the freon . If you where you would know what the psi should be. After the long long post. Id say you have played with it to much and now Have contaminated the unit with noncondensables and you have a leak.

ED

ED,

Thank you for your response. The pressures are holding up to what it was two days ago. How do you figure it has a leak?

Also, yes I do know about the EPA rules. But I used to put freon in my truck back in the 70’s long before the EPA rules were even in effect. The recharging process hasn’t gotten any more complicated since then, has it? I’ll admit, I didn’t know what the pressures should be since I am not an AC technician, but I did ask a certified technician about it. I was just trying to verify the expected pressures with someone else in this forum who knows this stuff. I’m not justifying it, but I do know how to bleed the lines to keep from contaminating the system. Well OK, I didn’t recover the little bit I bled out to clear the line, since I don’t have a way to recover it, but I'll deny it in court and I’ll go to confession tomorrow after church :) but honesty, I have never seen a technician ever recover the little bit that they bleed out of the hoses before they recharge a system. Not even the EPA certified ones. In any case, I don’t think I have introduced any non-condensables into the system.

If I was a (EPA certified “AND” an A/C technician), logic would dictate I wouldn’t be in this “Do It Yourself” forum asking questions, but I do respect your answer. I am not criticizing you, really. Any answer to my question is better than being ignored. LOL

By the way, I once did get my certification to work with freon, because I used it as a dielectric many years ago when working with up to a million volts. But, it has nothing to do with A/C units so that is why I am here asking questions.. They have since changed to a different more environmentally friendly dielectric gas, but it will just kill you instead. LOL So I don’t know if my certification is still valid, but I am also very concerned about the environment because I have to live here on Earth and so do my children and family and so on.

I also don’t have a problem calling up a certified technician. I just wanted to get an idea of what could be wrong with my system to better determine if I get an honest answer from the technician I call up to diagnose the problem with my A/C unit.

Thanks again ED

Robert

I am also very concerned about the environment because I have to live here on Earth and so do my children and family and so on.

Take the time to read this.

http://www.toad.net/~jsmeenen/freon.html

ED

Not being a smart a@@ but why did you ask a certified technician what the pressures should be then not charge to what he told you?

He told you 60-80 psi low side and 275 psi high side.
You charged to 63 psi low and 230 psi high side.

ED,

Thanks for the link. It is very interesting. Was that information intended to support me in releasing a small amount of R22 into the atmosphere or was it intended to make me feel guilty about the other typical pleasures in life that are so common in households today? :) If it makes any difference, I don’t own a swimming pool and never have. It’s not that I wouldn’t enjoy using it, I just wouldn’t enjoy maintaining it and cleaning it. So. I choose not to have one, ever. I also don’t use bleach to wash my cloth. It’s not that I don’t want nice looking whites, but I have a septic tank and I don’t want to kill off the good bacteria. At least that is my logic, but I’m not a chemist or a septic tank cleaner.

Anyway, let me change my post request a bit. But first let me say this stuff about AC units. It is not rocket science, but yes, it takes some skills to work in this field and I respect that. Still,. I opened up and panel to my system for the first time in 10 years (because I am a curious type of guy) and in a short time I figured out what the components are that can typically fail with a condensor unit and what they do in general. I mean, we have a compressor, a thermal switch, a low pressure switch, a solenoid coil to operate the reversing valve, a small circuit board with test points that measures the sensors and responds to them, a contact relay switch, a dual 5/45 uf 370V capacitor, a ceramite PTCR thermistor and a condensor blower fan. Yes then there is the air handler and evaporator and the thermostat, but they are not the problem I am having with my system. What I don’t know and have no experience with, is diagnosing the symptoms. This is where experience comes in and which is why I am asking the guys here that do know more about this stuff or they should anyway, for help, before I call a qualified technician and take my chances! LOL OK just kidding about that.

So, what I am really asking for here now is, I just want to know what could be the problem with my system so when I call the tech, if I feel I get a service technician who I don’t think is being honest and straighforward, I will just pay him for the service charge and look for another tech. I do know a couple of certified techs, but they are too busy with work at the private company they work for, they don’t have time to do side jobs and they also live about 20 miles away from me.

Thanks

Robert

CovTiger,

Hey, no problem. No offense taken.

Well, you see, I am the product of our education system that corrupted my mind years ago. :) I figured that if I would error, I would error on the safe side (low side). With the low pressure at 63 psi, I figured that I satisfied at least one of the conditions. But wait, there’s more. Taking into consideration the fact that I charged it very early in the morning when the temperatures are low like 95 degrees cool in the desert southwest, I figured Boyle’s law on gases, or is the ideal gas law???? Doesn’t matter, it is one of those laws that some smart dude figured out long ago when he had nothing better to do, right after eating a whole bunch of beans. That gas law would apply here, that states when the temperature outside at around 2pm or 3 pm would be about 118 degrees and the unit would be in direct sun, the pressure would also rise in proportion to the temperature. How much pressure rise would result? I didn’t know, so I just kept it low and hoped at that pressure, it would at least make a difference in getting or noticing some cool air coming out of my vents. Well, it didn’t.

I really don’t go around telling this stuff to just anyone, honest, but since you asked I just had to answer and hope you will understand or at least forgive me for trying to apply what I paid hard earned money to get educated on. Sometimes, it doesn’t always come out looking that way in the beginning, I know, but there was some logic to my approach in how I recharged the system to those pressures. :)

Anyway, I used to think I was resilient, just like Gumby! But now, if any of you know what it is like to sit in a house without AC when it is 118 degrees outside, you all would have a little compassion for me and help me out. sniffle… sniffle… :(


LOL… LOL

Thanks

Robert

Rob,

My post was a question, yes, but maybe a clue too :)

Your coil was only partially sweating - a sign of low refrigerant. There is more to charging a unit than pressures. The pressures your tech told you would be a little high for me in my area but it isn't 100o at 9:30 am here.

As Ed stated you DO have a leak. You won't see it reflected in the pressure over a few days with a small leak. The way we know you have a leak is the fact that you needed freon. Your a/c is a sealed system and should never require the addition of refrigerant unless it has leaked out.

The reason your suction pressure was screwed up in heat mode is you didn't have your gauge screwed on the proper fitting.

I always charge my unit after cleaning the condensor. I just make sure it is completely dry for charging.

I would error on the safe side (low side). With the low pressure at 63 psi, I figured that I satisfied at least one of the conditions.


Dont forget we do charge a system by the outside temp But on the suc side its a lot in what the coil burn off is do to the inside home temp or load in there When in AC.

ED

Dont forget we do charge a system by the outside temp But on the suc side its a lot in what the coil burn off is do to the inside home temp or load in there When in AC.

ED
hmmm... I see the quote thingy doesn't work.


… And that’s exactly why I need to call a real qualified technician. It just takes me a while to catch on sometimes. I have always been stubborn and like to figure things out or at least understand it if I can without messing anything up big time or killing anyone in the process. :)

So, have you guys had enough or do you want more!!!??? LOL OK… OK just messing with you guys a bit.

Seriously, I did again check out the air handler today only and I will call the tech tomorrow, honest. :) But I would like to run one last thing through you guys and I do appreciate all the feedback so far.


I took the side panel off the air handler to check out the evaporator coil (the AC is running) and I noticed when the airflow through the filter was reduced, since the side panel was off and the closet door was open, the evaporator coil got cold. When I close the door to the air handler, which temporarily simulates putting the side panel back “ON” and then check the evaporator about 10 minutes later, the coil was not cold to the touch. It’s like the coil didn’t handle the increased airflow through the filter to keep it cool. I did this a couple more times to verify it's repeatability. So what give here? This will be my last question. I will let you all watch TV, play with the kids, or such after this.

I am just curious about this big time. It is still low on R22? The filter is clean, along with both sides of the coil. By the way, the metering device to the evaporator coil is a capillary tube if it makes a difference. If anyone can answer or explain this to me, I will take out a life insurance policy, make you the beneficiary and then kill myself to show you my appreciation. :)

Thanks again for having patience with me.

Robert

Your unit is low on freon. When you remove the door there is no or little air passing the coil. The temperature and pressure of the refrigerant drop and it feels cold. Leave the door off long enough and it will form ice.

Refrigerant works on a pressure temperature relationship. When you look at the gauges you used to charge it you will see a temperature scale for r-22 at the given pressure. It sounds like you do not want to charge it to what the tech advised so I would recommend you call one out to do it for you.