any hvac guys on here?

Have hopefully an easy problem.

Bought house and had ac tuned up, low on coolant but overall units good shape minus secondary overflow being utilized.


Replaced thermostat with programmable unit and came home to ac off and heater on full blast.

Called home warranty people, they replaced thermostat. Worked fine for two months.

Lately we only run ac during day. 80f. At night not a dipping into 60s, but the outside compressor is always running. Sounds like unit in attic is off though.

Even with no thermostat it keeps running. I throw breakers and it kills it.

Today one of the valves is frozen. Wtf is going on?

 

I wouldn't worry so much about the valve having a little frost on it as much as I would be concerned about the compressor constantly running. Seems you have an instrumentation problem. Could be something wired wrong,a stuck solenoid, or a bad control panel. Either way, if it is under warranty, or you have a contract with an HVAC company, it will be an easy fix for them. The frost on the valve is just the freon going through the expansion valve and getting cold, and then the moisture collects on it and then frosts over, this is normal.

 

It was at least a 1/4 frost but OK.


We will call company, but as far as warranty, they've been out a lot to fix simple problems. I'm not a big fan but we will see.

Wish me luck!

 

Any amount of ice build up on the suction line is NOT normal. It's likely freezing due to the compressor running continuosly and the indoor unit not.

 

Had a similar problem with the unit for our tent in Afghanistan. TXV was stuck. Definitely get it checked out.

 

Does the compressor constantly run ? Or is it short cycling ?? If short cycling could be heat anticipator in T stat, if constantly running ya might want to clean the "A" coil inside your S/A plenum, probably 80%-85% of failures are due to dirty coils, which of course if coils are dirty they'll ice over like a skating rink, the T stat call for cool will never be more than warm air & your compressor will beat itself until dead trying to satisfy that calling for cool...

Regardless of whats causing it, try cleaning entire system first (which is usual maintenance anyway) before going broke throwing parts at it...

 

The "HEAT" anticipator coil has nothing to do with the cooling cycle. Chances are he doesn't even have that as that is very outdated technology. Also, it's more likely that a dirty filter would be causing the air flow issue than a dirty a coil. Unless OP has been dry walling his entire house or using a saw building bird houses right next to his furnace, or if he has 8 dogs and cats with the filter pulled.

 

out dated or not & probably doesn't have anticipator short cycling can still be related to either heat or cool & the highlighted above is a myth, you think a filter is going to catch everything ? Go look inside a duct at the register & comments like dry walling his entire house, or sawing bird houses next to furnace is nonsense, I could show you coils that are little more than blocks of ice & why ?? dirty coils my friend

 

Or, you don't actually know how to read a set of gauges and charge a system correctly. Or, you don't know how to charge a system based on the type of metering device. Or, well, there are many other "or's"
I'm not here trying to get into a pissing match. Does it happen sure, I'm not gonna say it doesn't. It does NOT however, happen as much as apparently you seem to think it does. Are ducts dirty? Yup! That's why you, and every other "entrepreneur" (if you are) out there with a slightly higher than avg, technical IQ try to sell retarded "duct cleaning" services. Do coils get dirty over time? Yup! I get that, and I have seen it also. Almost always in a commercial or industrial atmosphere. My point was that unless the OP, in a residential setting, has some extraordinary, or heavily soiled environment inside his home (cats, dogs, drywall, lives in an actual dust cloud...whatever) it's more likely the air filter is what would be causing an airflow issue. If there is one (an airflow issue). I'm not throwing out a diagnosis here, simply stating a factual discrepancy in yours. And now I know you are gonna tell us all how you have years of experience and blah blah blah....sure...ok. If that's true...whatever, I'm glad you aren't in a position to attempt to sell anyone I know any of your snake oil. If you don't have any actual HVAC experience, stop trying to google the answer.

Edit: If the AC is short cycling......any good technician would NOT think a "heat anticipator" had anything to do with it.

 

This is easy. I can almost guarantee that the contactor on the outside unit is "stuck" ( welded from arcing when the contactor is energized) , causing the compressor to constantly run even when the thermostat isn't calling for the unit to be running. That is why your suction line is freezing because your not getting any heat exchange through your indoor coil because the fan is off. I'm an industrial refrigeration technician for Tyson foods. I have over 7 years of experience in the refrigeration and HVAC field.

 

Also he has a digital stat which does not have a heat anticipator. And frost on the lines is never normal. Frost means liquid is sitting in the suction line which is bad. Your compressor is designed to compress vapor not liqud. This can happen when your coil is dirty as stated above, an expansion device that is either clogged or stuck, the unit not charged correctly. And with people who have a heat pump at your house, you will probably see the outdoor coil frost up especially on cold nights. This is due to not enough heat exchange through the outdoor coil. If its under 36°f outside your heat pump is pretty much useless.

 

Every one who was talking about the filters is right. Unless your filter is directly on the unit. Dust will find a way in, your indoor coil makes water, water+dust=mud. I have cleaned plenty in my time. And the only way to truly get one clean is to pump the system down, cut or desolder your lines connected to the coil, pull the coil out, clean it with acid, wash it out really good and put it back in, then pull a vaccum on the coil and lines until you have 1000 microns (30inhg) so no air or non condensables in the lines, recharge your unit, check pressures, done.

 

Been in the HVAC trade for 25 years and I can tell you xxOkieTacoxx knows his stuff. We know there could be several different causes, but a fried contactor is the most common. I also agree sucking back liquid is hard on the compressor. Good luck...

 

I know I'm a litte late on this one. Wtf is a secondary overflow? are you referring to a receiver?? I hear so many stories of HVAC guys just saying a system is low on refrigerant and then charging some in and calling it good. Well there is probably a reason that its low on refrigerant IE a leak somewhere. Refrigerant just dosent disappear. I'd be willing to bet that your suction line was frosting heavily because the refrigerant that your guy charged in leaked out and its low on charge again. Alls I'm sayin is simply charging a system back up with a few pounds or whatever is not necessarily the best answer. Hopefully they leak checked before doing so.

 

Secondary overflow probably on condensate drain, primary blocked.