AC keeps freezing up (indoor and outside units)

Unit:
Residential AC 10-11 YRs old

Temperature outside is in the 90s and humidity is around 30s or low 40s
Thermostat set at 70

Trane XB10 outside Air conditioner unit
Model 2TTB0048A1000AA

ADP evaporator 450PSI R22 refrigerant
Model TA06248C175B250584

Background:

3 Years ago unit was freezing up. Called HVAC and said it was low on refrigerant. They filled it up and left.

1st Issue (last week):

Outside unit started making clanking noises. No cold air was being produced. Went outside and the fan was on operating on the unit. Turned it off and called HVAC technician the next day.

The technician came out and said it was the condenser fan motor that died. He didnt have the part so had to order it ($600). It took two days. Installed it and hoped this issue did not break the condenser as well. He also filled up the refrigerant since it was low. He cleaned the outside unit filter as well (the filter that goes around the unit). It was very very dirty. It worked great for the day and the night. However, the next day the pipes were frozen.

2nd Issue (now):

The pipes are frozen and no air flow coming through vents. Turned off AC and turned on the fan. Still no airflow. Called HVAC technician again. While waiting, the pipes thawed out and I noticed water near the inside unit (under the furnace). Therefore, thought it must have frozen the A coil (evaporator) as well.

HVAC technician (same company diff guy) came out thinking it was low on refrigerant. It of course wasnt because it was filled the previous day. Told him the condenser fan motor was replaced. He checked the filter and it was fine. (Usually replaces every 3month, now know every month).

He opened up the inside unit. Saw a bunch of liquid in the bottom pan. He said the condensate pipe was clogged. Also said the A coil has a leak. It had some oil as well as small small bubbles. He gave us some options:

1. Solder/weld/braze the copper pipe leaks on the A coil. Another leak would end up popping up later on.

2. To replace the A Coil evaporator. ($1200) But then the compressor or condenser might be the next thing to go.

3. Replace outside unit and inside unit with brand new system. ($4600) He would refund the fan motor price as well as refrigerant price if we chose this. He highly recommended this. So we did. He turned off the unit and the replacement could not be done for a couple days.

We felt sick to our stomach though for having to buy a whole new unit and kept having second thoughts. We are planning to sell the house within a year. Also kept thinking why would the leak all of a sudden cause it to freeze up. Apparently we have had a leak for 3+ years because we had to fill up the refrigerant 3 years ago.

Anyways they came out to replace it yesterday. They ended up having the wrong size evaporator. So the two installers decided to blow out the condensate pipe (the drain was buried underneath landscaping all these years. Dug a hole around it). They also solder/brazed/welded the leak in the A coil evaporator. Recharged the system and said hopefully this will last the rest of the summer. They also thought it was odd that it was freezing up.

It worked yesterday and last night. I kept checking both units and the outside unit only had some moisture on it before i went to bed. This morning, air flow was reduced out of vents and pipes were frozen inside and outside. Turned off AC and turned on the fan (it was set to auto last night).

Any suggestions? I have been in a house at 90+ the last week and almost desperate.

EDIT:

It thawed out for 3 hrs. Turned it on with the fan on as well. Outside unit sounds good. The furnace blower fan sounds rumbly and the evaporator sounds kind of like a snake hissing although not constant. I am not sure if this is what it sounded like before it was freezing up.

 

Welcome to the forums.

One of the advantages of a new system is selling point. People want A/C. If you sell your house with an old non working system they will try to deduct for it anyway.

In your case it sounds like the evaporator coil is shot. It's very rare that one leak can be found and fixed without causing more leaks. They probably didn't have the time to completely evacuate the system and charge with nitrogen to check for leaks.

These kinds of problems are hard to troubleshoot like this on a forum. The two major things that cause the coil to freeze is low on refrigerant or not enough airflow across the coil.

 

Thanks PJ.

I would think the refrigerant level is okay. And apparently there has been a leak for 3+ years since the refrigerant was filled back then. So why all of a sudden after the technician replaced the condenser fan and cleaned the outside coils would this freezing problem be happening.

I got to see the A coil and it looked pretty clean on the coils. There was minimal buildup. There was some but not even close to the images online of dirty evaporators.

Could there be a problem with the service ports (due to technician working on the system) such as a new leak. Could there be a problem with the capacitors or the blower motor inside?

It just seems weird that there has been a leak for a while now and then once refrigerant is added and the condenser motor replaced it freezes over. It works fine (with airflow) but freezes over night even after the evaporator leak was fixed. As well as fixing the condensate pipe from being obstructed.


Say we did get a new inside and outside unit. How can we be sure it wont happen again due to possible bad existing piping underneath the house from outside to the inside unit

Thanks again for your reply

 

Usually, when a new system is installed, the line-set (pipes from indoor to outdoor unit) is also replaced (unless the system is only a few years old). Make sure that the new installation (should you decide to go through with it) includes a new line-set.

 

thanks bob. i will make sure that is part of it if we do replace it.

should i attempt to clean the evaporator A Coil without removing it?
I checked a little bit ago and both pipes inside and out have a little moisture


also right now the unit is a 2.5 ton or 3 ton and is 10seer.

he wants to put in a 4 ton 16 seer unit. is that overkill?

 

Anyone touch my service port, I'll check the leaks immediately after by using soap water. 40% of the time, the service port leaks and only 20% of the techs check it after. In fact I check all connections they touched by using soap water, I don't trust them, I don't trust myself either. so check it out and I can sleep well. Replace fan motor would not cause a leak, but recharge freon will.

 

still, should a leak cause pipes freezing up? I thought over time a leak would due to low freon. I have enough refrigerant or at least more than what I was at and had no freezing. all of a sudden i get more refrigerant and a new fan condenser motor and it freezes over night.

 

Leak causes low freon which causes freezing most of the time, (weak air flow causes freezing too). You had no freezing before because you had no leak, at least not a major one, Now after they did something to it, you won't know if the system has a leak or not, or a big/small leak, so that was why I said, check it out.

 

right now the unit is a 2.5 ton or 3 ton and is 10seer.

he wants to put in a 4 ton 16 seer unit. is that overkill?

house is 2700 sq ft. price is $4600.

does this sound correct?

 

$4600 for the whole system (both new condenser and evaporator coil, includes all labor costs) is reasonable to me. need to know the brand and model. 4 Ton for 2700 sf house is about right. However, You only had 2.5T before, did 2.5T provide enough cooling power to your house before ? Need to ask them why 4T , not 2.5T ?

 

Need to verify that the ductwork can handle 4 tons also

 

The house with the 2.5 ton is supplied to two floors. The second floor (upstairs) is always hot in the summer. The house should have been built w an ac unit for each floor.

He said the 4ton is more adequate for the house sf. the unit is a York *13 seer. Not sure the model.

How can one tell if ductwork can handle it? If it didn't would it just be costly for bills or would it not cool the house adequately?

There are two return vents upstairs btw.

 

Btw, could something be wrong with the thermoexpansion valve or the metering device for the refrigerant. It runs all day fine until the night time when the temp outside drops to 65 and In the morning it's iced up a little

 

If the ductwork us undersized for the 4 ton, you will have freeze up problems also.

 

Anyone that has been in the business should know how to run a ductualtor and know if your current duct can handle it. I'm strictly guessing, but I think you have a tract home where minimum sizes were installed. Hope I'm proved wrong.

 

it could have been possible that min size were installed. however, the houses in the subdivision are all different and have different builders.

it sounds like anything could cause freezing up. i just cant wrap my head around the fact that the system was low on refrigerant and it was working besides the fan motor failing. then after filling up the refrigerant and replacing the motor, the pipes freeze at night.

so yesterday we ran the system, it cooled the house and before bed we turned it off. this morning i turned it back on. no freezing during the day. just some moisture on the outside unit copper pipe.

if it was airflow problems wouldnt it freeze up immediately?

and the system has had a leak for years since we filled refrigerant 3 years ago after it froze up.

 

clocert -

with the soapy water, do i have system set to off or can it be done with it on.
and i just spray the copper tubes at the outside unit? if there is a leak, i am assuming i would see little bubbles?

 

You do it with the system running so that the lines are pressurized. Personally, I would just rub the soapy solution on by hand, but you can spray it on if you wish. If there's a leak, you'll see bubbles.

 

Thanks bob. I will try that.

I am also going to try to turn the thermostat up and see if it shuts off the AC inside and outside. Just to make sure the tstat is functioning properly.

EDIT

Thermostat works. I turned it up and the outside unit shut off then the inside unit shut off shortly after. Turned it back down and about 4 min later it all turned on.

I sprayed soapy water as well as with my fingers on it. Doesnt appear to be any leaks. The soap bubbles just pop and goes away.


Any other ideas?

overcharged?
blower motor?
thermoexpansion valve?
metering device?
contactor?
capacitor?
blower relay?
ductwork?
outside coil damage (due to tech cleaning it - it was very very dirty)

 

It is good to hear there is no leak at the ports, but the leak can be anywhere, as you mentioned you had to refill after 3years (that's a very small leak). So far, no one has asked you about delta-T yet. while the system is running, measure the temperature of input cold air and temperature of the return air, the difference is the delta-T, should be between 15 and 20 degrees (assume the air flow is normal, another word, pretty strong that you can feel the cold air from 10 feet away. )

 

I thought the leak was small as well. The leak on the evaporator was very very small. So I understand why every 3 years it needed to be recharged. Anyways, i tested the supply air near the vent and it was 60 deg. The return vents are a little tricky and i could only get the thermometer near the outside of the vent. It is 73.5 deg.

Delta T is 13.5. But I am sure it is greater if I could get the temp inside the actual return vent.

I have some of the pressures on the sheet the tech gave me. Let me go get em

 

The following parameters are after the fan motor was replaced and coolant was added (1lb r22), but before the evaporator leak was welded, fixed and once again the system recharged. I did not get a copy of the parameters after that.

I am assuming unit 1 is the outside unit and unit 3 is inside unit.

Parameter Unit 1 Unit 3

suction psi 56 57.5
discharge psi 261 211.1
super heat 39.1 9.0
sub cooling - 6.9
OD temp 75 82
ID temp 82 80
SA Temp 32/ 33/106
contactor ok yes yes
comp amps 23.7
cond fan motor amps 1.2

 

Unless your duct is not insulated well enough, the 13.5 delta-T is a little low. We can not discuss pressure or SH or SC on this forum. I'll let PJmax continue this thread from this point on. Just remember, 13.5 (at the register vent) is not acceptable, it will cool you down, but there is still a little problem somewhere.

 

i apologize for posting the parameters. I, myself, cant do anything about them. I just thought it would trigger an alarm or something and then i could let a technician your suggestions.

even if it is a simple, the parameters are off. talk to tech about the this parameter.

all i know is, the house is at 74 right now in 100 deg weather outside. when it isnt working it gets up to 90 in the house. turning the ac off at night is a short term relief but i understand there is a problem somewhere.

 

That's a high amp draw on that compressor IMO

 

Referring to something listed on a report by a certified tech such as below, and replying "that XXX is too high/low and they need to come back" is acceptable (at least by me). Saying what something specifically SHOULD be (even a range), how to check or adjust it, is NOT acceptable. Still no discussion allowed of charging or sealed system testing.

This is something that has been discussed separately, and I think it's a reasonable compromise.



To jtstp17, I'd caution you about telling a tech who has been hands on with your system that you got some suggestions from an internet Forum. If I was a Pro I don't think I would appreciate that. Maybe asking him to explain a bit, or stopping by the shop and asking someone else saying it's still not cooling well?

 

tinmantu -

i got some more information.
the comp motor RLA stated on the outdoor unit is 19.7 (105:RA). So 23.7 doesnt seem to high, correct me if i am wrong.

i also checked to see if the first tech put in the wrong fan motor. it seems to check out.
OD motor stated on outside unit: 1.3 FLA 1/4hp

fan motor stated on the motor itself: 1100RPM, 1.3 Amp and HP 1/4. the tech tested fan motor amp at 1.2

those in my opinion seem to be okay. again, correct me if i am wrong

gunguy -

of course! i wouldnt do that. it would be more in form of a question.
an example is:
- the last test on the comp motor looks like it was 23.7 and on the unit it says 19.7, is that okay?
- could the blower motor be causing the issue? like if it wasnt running full speed?

stuff like that

 

If you look up RLA, that's the MAX it should normally draw at start-up, so I agree, I think that's high. I'm not sure what's indicative of though. Wear? Age? Insulation breaking down?

 

I'll let gunguy handle it from here, or he might shoot me.

 

Oops...sorry, got my RLA and LRA mixed up.... RLA is Rated Load Amps. LRA is Locked Rotor Amps. Confusing that they used 2 acronyms so similar.

From what I read, RLA would be max running amps and should normally be lower than the nameplate number...at least according to some Pro's at another site.

 

Hey, no problem Tinman...I'm no expert (as you can tell by my last post). I'm just up late and trying to help out while worker types get some sleep for tomorrow.

 

so the compressor is working harder than it should. could this cause the freezing? or would it just cause the compressor to have a shorter lifespan

 

also, how can i check if the blower and blower motor is working correctly? it sounds like it is moving at a low speed.

 

Anyways, I had a second opinion come out today.
I didn't tell him much besides it was freezing at night. I told him the whole story and everything after his diagnostics.

All the parameters were good. The Delta T was 20 deg, the contactors, capacitor were good. The refrigerant was good. He even said the evaporator looked good.
He did alot more diagnostic than the other company.

He suggested cleaning the blower motor and cleaning the evaporator. But said both are not bad and can not guarantee it will solve the freezing problem. We went with the evaporator cleaning. We also have an estimate of a new system coming out early next week to do a load calculation.

Talking w him sounds like when the outside coil was dirty w/ debris, it caused the pressure to be higher (which most likely caused the leak in the evaporator main tube) but made it so the temperature did not drop below freezing. Then when it was cleaned, the pressure was reduced which resulted in a drop of temperature and causing it to freeze at night.

Does this sound right? I still don't understand whats wrong with it.

Every tech that as come out as changed the dang filter. First was no allergen to a simple filter. Second changed it to two filters. This one rearranged the two filters.

I like this second company better but am already $1300 down with the other company for the outside fan motor replacement, condensate unclogging, leak fix, 2x recharging the system. Thus, if anything that load calculation will tell us what system size to get and I can order it through the first company so they will deduct the $1300.

Do any of you have any other suggestions or guesses on what is going wrong? Hopefully tonight it wont freeze with the evaporator being cleaned.

 

Make sure all your vents are open. We closed two vents on 1st floor to send more air up to 2nd floor, coil froze due to low air flow.

This issue pertains to my house having bad duct design, but still something to think about.

 

all vents have been open

anymore suggestion?

should i try getting the blower cleaned?