Carrier A/C, Again!

[Nandy]

For the last 3 years around this time this ac breaks. I dont know if it is the border line temperatures where the heat is on at the coldest point of the night and the ac kicks in during the other times. Last 3 breaks it has been the dual condenser fan/compressor starter capacitor. Yesterday the ex call me that the house was hot and the ac was not working. I told her to go out and check the 2 lines coming from the outside unit to the unit at the attic. She said the line outside was frozen, she did not get in the attic to check on that end. Sooo, this will make me think it is not the dual capacitor because the compressor would not work and cool the line enough to freeze it. I cant be the compressor because again, if it dont work it could not get the line cold enough to freeze. So either there is not enough freon on the line or a filter is plugged? Those were my thoughts but then im no ac tech, just a handy man.
I told her to turn the ac off and turn it on again after the line is not frozen. I arrived today to get my son and the house is hot and the ac was still off. I turn it on and it is cooling the house again and the line up is cold and the return line is hot as it should. It remains to be seen if this happen again so this might be a moot point. However I would like to know from those ac experts in here what they think could have cause this line to freeze.
Thanks!

 

[BuzzStPoint]

Re: Carrier A/C, Again!

I used to deal with the frozen lines all the time at our hotel.

The condenser coils are probably plugged with dirt and dirt.
We have a train, I pull the outside covers off in spring and hose off with a garden hose till clean.

Since I've been doing this once a year I haven't had the frozen lines.

 

[mike243]

Re: Carrier A/C, Again!

evap motor not running,take your pick why,my bet is capacitor,dirty airfilter,dirty evap coil,low on freon,i hope its a dirt issue,a dirty condenser unit will run high head pressure & no frost on the suction pipe{bigger line} long run times find weak points in any thing & ac's tend to have problems when it gets hot ,make sure the inside fan motor is running if it frezzes up again,if not pull the capacitor & take it somewhere to have it cked,good luck,mike243

 

[Nandy]

Re: Carrier A/C, Again!

It happened again a day after I turn it back on. This is where my ex lives so I'm not there all the time. I will try to clean the evaporator and condenser. I know both fans work when I'm there but who knows. I will try to get the stuff that I can out of the way before calling someone.
Any other input from the knowledgeable a/c techs here will b welcome.
Thanks.

 

[a70eliminator]

Re: Carrier A/C, Again!

Dirty filter in the blower compartment number #1 cause of freeze ups.
Low charge #2
Something really stupid like a rug laying over the return air intake, but yours being an attic unit return air is probably up high on the wall.
Pressure and temp readings would be the next step.

 

[SS MAYFLOAT]

Re: Carrier A/C, Again!

What kind of set up do you have for the evaporator blower motor? Is it direct drive or belt driven? If it is belt driven, the belt could be worn causing it to slip reducing the RPM to drop and cause it to freeze up. Are the vanes in the squirl cage blower full of dirt? Dirt buildup on the leading edge of a vane or blade of a blower can reduce airflow big time.

Low charge will cause it freeze up as well. Also see where she is setting the stat setting. I've had people set a stat in the lower 60's only to have the system freeze up over night with outside temps being low.

 

[dgopetactical]

Re: Carrier A/C, Again!

Dirty filter in the blower compartment number #1 cause of freeze ups.
Low charge #2
Something really stupid like a rug laying over the return air intake, but yours being an attic unit return air is probably up high on the wall.
Pressure and temp readings would be the next step.

Most of the start up issues I have delt with in the last 2 weeks are #2 low charge/ carriers are known for evap coil leaks in some of the slightly older mods they had oversized coils that did alot of rubbing that result in leaks.
Low charge is mosly what I run into with situations like yours. Check for oily residue in the bottom of your air handler/coil and in the bottom of you outside unit. and when you do that check your filter.
Denny

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

First of all a heat pump running in heat will never, ever freeze the line set as the suction line(big line) becomes the discharge line and the liquid line reverses flow from hot liquid to the indoor coil in cooling to towards the outdoor coil in heating....

If the outdoor temperature is low and for some reason you run in cooling the unit can freeze due to low load...units freeze for two reasons...#1 bad heat transfer at the coil...meaning slow fan, dirty coil, dirty filter, and sometimes chemical buildup or grease or something that coats the coil and blocks the fins of the coil from directly getting to the airflow...

reason #2 is low charge causes refrigerant to flash in the metering device at a way lower temperature then freezing and that + superheat is still below freezing and the unit starts to freeze at the txv, or distributor tubes and then works its way through the coil back to the compressor...

So basically how it freezes can tell if you have a transfer problem or metering device/charge problem, but you don't have a a capacitor problem unless the outdoor unit is the one freezing in heat mode due to your outdoor fan shutting off from a bad cap or motor...

 

[Nandy]

Re: Carrier A/C, Again!

Thanks for the replies guys, I just got back to day from a extended fishing trip. Will go tuesday to the ex house and look at it. we are putting this house in the market and I need to have it ready..... the market sucks for sellers..

 

[yourkiddin]

Re: Carrier A/C, Again!

im sorry to hijack your question. but since there is so much knowledge here and i seen the statements about the evaporator coils, i cant resist. i was told that on my goodman unit the coils had leakage also. i just recharge every year. but today a friend told me that the ac man put some kind of stop leak in his over 5 years ago. can anyone comment on this. and also my evap coils had froze up. most likely due to low freon.

 

[SS MAYFLOAT]

Re: Carrier A/C, Again!

im sorry to hijack your question. but since there is so much knowledge here and i seen the statements about the evaporator coils, i cant resist. i was told that on my goodman unit the coils had leakage also. i just recharge every year. but today a friend told me that the ac man put some kind of stop leak in his over 5 years ago. can anyone comment on this. and also my evap coils had froze up. most likely due to low freon.

Yes there is products available that will plug leaks. There is pro's and con's of the product as well. I've used it with much success, but there have been some units that it made a complete failure of the unit as well. There is different amounts for the size of the unit and directions need to be followed to the "T". It does need to be installed by an experienced service tech.

This stuff (as I was told by my wholesaler) gets carried through the oil and circulates through the system.

 

[mike243]

Re: Carrier A/C, Again!

i have seen compressors get locked up by using stop leak,it reacts to air & moisture & the only way to make sure is to pull the charge vac & recharge & then add the stop leak,its a last ditch effort to keep from replacing the part/unit due to age,mike243

 

[mike243]

Re: Carrier A/C, Again!

also heatpumps use less of the freon in the heating mode & folks think that it just got low when its been a slow leak for some time,.r22 hasnt went ^ on the price yet but its coming 1 day,good luck,mike243

 

[a70eliminator]

Re: Carrier A/C, Again!

i have seen compressors get locked up by using stop leak,it reacts to air & moisture & the only way to make sure is to pull the charge vac & recharge & then add the stop leak,its a last ditch effort to keep from replacing the part/unit due to age,mike243

If you try to pull down a leaking system all your doing is introducing more non condencables into the system, if the system is tight there's no need for stop leak.

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

If a unit won't hold a vacuum under 500microns it has a bad enough leak that you need to address it, period...Everyone thinks that a slight leak is OK and just add a few pounds a year and its fine...All leaks can be found and fixed, its just a matter of whats practical...Stopleak type stuff is worthless and I would fire anyone that worked for me that used it...

Also where your leak is matters...if its in the evap coil or on the low side of the system in cooling its not going to leak as fast in the summer as it will in the winter when it turns into the condenser coil for the heating season...The tendency of when you have to recharge a heatpump can point you in the right direction for a leak...

With r410a or puron as carrier likes to call it, it is a blend of two different refrigerants(50/50 blend of R-125 and R-32) and they leak at different rates...If you have a slow leak with 410 and you just charge it up and move on eventually the refrigerant will need to be reclaimed and you have to start over due to one leaking out more because its heavier then the other...

 

[Nandy]

Re: Carrier A/C, Again!

Ok, so I cleaned the outside condenser Monday which was not that dirty or plugged. I let it dry overnight. Power up the a/c and went into the attic unit. Open up the section where the blower is and did not see any filter there. It was kinda awkward and looking thru the blower itself. There are filters in the ceiling at the first and second floor which are the 2 return ducts coming in to the blower. Open up the other section past the evaporator and the evaporator looked clean. I could feel the strong cold air from the blower passing thru the evaporator fins. Did not see any dirt in the evaporator at all. This is an 8 year old unit. Left a few screws off and told the ex what to check if it freeze again. Well, it did about 6 hours later. She says the big pipe was frozen at the outside unit where the compressor and the condenser is. She climbed to the attic unit (2 story house) and no pipes were frozen there, neither the evaporator was frozen but she could feel it cold.

Here is the part that bugs me... She could not be to clear if the blower was working or not but she says she could not feel any cold air out of the room ducts. That on itself will tell me the blower was not working or the evaporator was totally plugged with ice... Then she will say it was working... If the blower was working and there was no air flow then definitely the evaporator is plugged with ice but she says the evaporator was cold and no ice... I tried to get an straight answer from she but I could not and she was starting to get aggravated ( after 22 year of marriage I can tell when she is) so I did not even try to ask if the motor was maybe running but not at full rpms... It is starting to look to me like it is low charge, what do you guys think? Im waiting for a coworker that has an a/c shop to see if he does houses or cars... Will have to take it from there.

what is the psi for this type of system? If I have to hire someone else I will have to be watching over their shoulders. Im sorry, I know there are a lot of decent technicians out there but you never know who you will get. I have heard many of my coworkers being told they need a new unit when the trouble was simple stuff as capacitors and low charge...

Thanks!

 

[SS MAYFLOAT]

Re: Carrier A/C, Again!

Have her see if a piece of paper the size of typing paper or a newspaper will suck to the fresh air return. If it will not stick to the return air, then the blower is not working or something is definitely restricted.

 

[Nandy]

Re: Carrier A/C, Again!

How many pounds will this system hold? I have someone telling me 99 dollars for a full checkup and up to 1 lbs freon and a ex-coworker telling me 150 for freon (it dont says what max pounds) and the check up if the charge dont fix it...

 

[SS MAYFLOAT]

Re: Carrier A/C, Again!

Usually on the condenser it should tell what the charge should be. It could be pounds/ounces or only ounces. It all depends on the size and length of your line set to the evap coil. It could take a few ounces or a pound. Having a charging manifold can tell how low your charge is.

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

Overall pressures don't mean much in a refrigerant charge...If its a TXV(thermostatic expansion valve) system then you charge to subcooling...Typically like 8 degrees or so...If its a fix metering device Its based on load and ambient temperature and indoor wet bulb...

Units always freeze in cooling from the indoor coil around the metering device in the liquid line to the indoor coil itself then back up the suction line to the compressor suction valve....If its frozen outside then 100% its frozen inside...Not being able to feel air when its frozen is normal...The coil is blocked with ice...if it runs long enough the indoor motor will overheat due to low airflow causing the motor to run under amps...it needs a certain load to keep it cool...So the motor overheated and stopped might be a byproduct of a unit that is restricted or undercharged...

As a homeowner all you can check if you are super handy is condenser approach temperature...that means the leaving air from the outdoor coil - the liquid line temperature...Typically you can expect like 14 degrees or so difference if the charge is "close" as it gets closer to 0 it means you have a refrigerant restriction... > 14ish is a different set of problems that you aren't describing...

Bottom line is if it runs for 6 hours "then" freezes it almost has to be airflow or overcharged if the suction line is really cold after the first 5 minutes of run time.

If you are in an area with 90 degree outdoor temperature and 78-80 inside I and its a 8 year old unit its probably a piston metering device unless it was sold as a high efficiency unit...I would suspect it to run 65-67# suction pressure with a 48degree suction line and a 235-240# high side pressure with a 102-104 degree liquid line...And more then likely hold between 9 - 15 pounds of refrigerant...

Does the suction line come back really cold after it starts and runs a few minutes??? If so that isn't undercharged its actually overcharged and flooding back liquid...