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Home HVAC Question??

kms254

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Ok I know this is not a "Home forum" but we have a lot of smart guys here so I thought I would ask.

Ok, its hot outside, I know this but my house is not cooling like it should. At night it was only getting the house temps down to 81, with the thermostat set at 74. I started investigating and found that the low pressure line was frozen over. I am a new home owner and we had a home warranty. I have always been quite skeptical of them, but I was hot, it was late and I was not thinking rationally. I called them to put a request in, and the service man came out yesterday.

He asked me what was wrong, I told him what I had looked at and what I had done, I showed him pictures of the low pressure line being frozen over. He asked if I had changed the filters, and I had. He walked out to the outside unit and said they were "severely dirty," before I bought the home in march I had an ac repair man do and inspection and he did not mention that they were even mildly dirty, but it is possible to get dirty so I was like ok.

He said it would be 99 bucks to have the first one cleaned and 75 for the second, we have two units, and upstairs works fine. He then told me that because it was so dirty the line pressures were up and he could not get a true reading and if he added freon to the system it could burn stuff out and cause other failures. He also mentioned that if we did not do it, he would tell the home warranty people and they would not pay out on any other claims for the hvac system. I felt kind of strong armed, but its hot and what was I going to do.

So the line pressure before cleaning was suction:50, high pressure 240, after the cleaning(he was really reluctant to give these to me and tried his best not to), suction: 56, high pressure 220. He then added a half a pound of freon and the final numbers was 80 and 275.

Ok, so the night comes around and the house is not cooling down less then 80, so we are a little bit better then where we started but not by much. I got a thermometer and measured the intake temperature to be right at ambient room temperature of 80 and the temperature of the air coming out of the registers to be about 75. Now remember this is at night, its still hot but not 100 degrees like during the day and it was late like midnight, so the residual heat should have been dissipated.

I think I got screwed out of the cleaning, but I figured at this point it was something that should be done twice a year and i watched closely at what he did and what products he used so i could do it myself in the future. I still don't think the problem with my ac unity is fixed. A delta of 5 degrees between intake and cooled air is not that much.

Does any one have any ideas, or know a trustworthy company in the jackson ms metro area?
 
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slice

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you learned home warranties ****, i am hvac guy in texas and deal with it all the time... you can clean the coils ur self water hose with nozzle start at top work ur way down....


when done wait 15 min feel big line a prperly charged system will sweat back and be about 55 to 60 degrees ( some variables) if not low on freon

temp diff between return and first supply 20 degrees

call a good company and have them look it over worth it
 

cowboyjosh

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Home Warranties are not worth the powder to blow them to hell. The last house I sold, the buyers asked for a Home Warranty, I told my and their Realtor my stance on them and I ended up just giving them $400, the cost of the warranty. As a buyer i hate it when Realtors give the sales pitch "this house also has a 1 year home warranty".

If you want the AC fixed right, your gonna have to call your own guy to do the job, otherwise you'll go back and forth with the worthless idiots the home warranty will keep sending out.

If anyone has ever had a positive experience with a Home Warranty, I'd love to hear it.
 

csp

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What kind of filters did you install?

If they are the kind that filter down to the finest particle they will hamper air flow across the coil and it will freeze up on you.

Go to the spun fiberglass filters if you don't already have them. A/C requires lots of airflow to work efficiently.
 
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kms254

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They did add a 1/2 lbs of freon to get it up to those pressures. We had one of the super filters, but when we started having problems, I got one of those el cheap-o 30 day filters that don't do much filtering.

I pretty much knew the warranty was a scam, the previous owner had purchased it before we started looking at the house. The idea to call them was an irrational decision, it was hot, late at night, and i had work in the morning so i was pissed and made a rash decision with out thinking it through.

So my question, Assuming filters are good, freon is at the correct amount and the pressures are right. What would cause a system to only cool the air 5-6 degrees below ambient temperature. I thought it was suppose to cool 17-20 under the ambient.
 

babzog

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IF you find a good HVAC guy, KEEP HIM happy! Many will try and screw you big time - seriously, this industry is like the stonemasons of yesteryear - preserve trade secrets at all costs! Carpenters will give you advice, so will plumbers and electricians.. but HVAC guys seem to be a different breed entirely. $99 cleaning - convenient figure. I had one guy from a well known local company quote me $250 to install a $99 thermostat!

I had a home warranty (free for one yr) when we re-fi'd our mortgage. Thank God I took it because our waterfurnace went out last spring! Called the HW and they had noone to come out, "call your own people" they said. Okay. The guys who originally installed the unit don't do it anymore , so I called the only registered Waterfurnace dealer in my area that was listed on the website. Turns out, they're a great outfit and the tech was super nice. He pronounced it DOA (compressor - shot, coaxial heat exchanger - shot). He suggested a new unit, the ins. company said "repair it". $5k later, it's working fine. In my case, the warranty was/is worth the money spent and I've found a great company to maintain the unit going forward.
 

hydramatic

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make sure your not pulling attic air in with the return air..If the suction side of the air handler is in the middle of the house,It may not be sealed up from the attic...as in balloon construction...like the above comments, call your buddies and find you a reputable A C tech..self employed..
 
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kms254

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Thanks for your advice, How do you go about cleaning the A coil? Any products? I know what you mean about a good AC guy. I'm 24, and just bought this as my first house, it was built in 97 and the hvac stuff is original to the house, and probably not maintained much by the original owner. I one of my very good friends brothers is an HVAC guy and lives here so I am going to call him tonight. I would trust his opinion and I would not think he would screw me over.

The intake is in the middle of the house, and run by a 20' long 2-3' wide tube, I looked over its joints and i did not see any gapping holes or broken joints.
 

Falcon67

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There are cleaning solutions for the inside (and outside) coils. I use a garden sprayer with a little dish soap on the outside and rinse to clean off the dirt. I vacuum the inside A coil once in a while - just be GENTLE with both activities so you don't bend up the fins. There should be an access panel near the coils in the unit, you can remove that and inspect.

FWIW - my daughter's last house had a home warranty. I told her to make sure the seller paid for one since the house had some old equipment. The AC unit was ancient and the compressor unit failed like 2 months after they moved in. Local AC guy checked it, said "whole deal has to go - too old to repair". Home warranty service paid for a complete new AC install, inside and out. Apparently they don't all ****.

seriously, this industry is like the stonemasons of yesteryear - preserve trade secrets at all costs!
Ya - try asking a DIY question on the HVAC tech forum. You'll be sorry LOL.
 
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1320stang

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They make a spray cleaner that you can buy at Lowe's in a aerosol can that you can use to clean the A-coil. The A-coil is in the inside unit, mine is an updraft unit, meaning the return comes in the bottom of the unit and goes up, so that is the dirty side. I made the lower box have a removable panel with foam sealant tape that I remove to inspect the coil. If the coil is pretty cruded up, you won't get good flow thru it and it will freeze up.

Another thing, you're in Mississippi, and it's probably high humidity, they don't work as well when the humidity is really high, btw, do you have a regular A/C unit or a air source heat pump? I believe the heat pump works worse when the humidity is really high. You'll know this because you'll be making a lot of condensate on the inside unit.

My house was built in '98 and I had to replace the outside (condensing) unit last month, my system is a Goodman. The fan quit working and locked the compressor up when it got hot, I threw $100 at a new fan but couldn't get the compressor to unlock, didn't want to try a hot-start kit on it so I bit the bullet. BTW I have a very good HVAC guy. :)
 
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kms254

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Sorry, I didn't see the HVAC section.

I will see what I can do and look at the A coil tonight, we have a regular A/C unit. I am wondering if i should call them back and say I did the repairs they suggested and its still not working.. I know its been 100 during the day but at night a house should get cooler then 80.
 

hydramatic

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I just went outside and used an infared point and shoot thermometer. the suction line is 55....the air out of the farthest register in the house is 57...it`s 100 ourside...you need to call those people back and challenge them...I have a 37 yr old mathis unit...
 

Falcon67

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I'd call someone else - the first tech already BS'd this problem, maybe time for someone else. $ spent = lesson learned.
 

was2

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While you are talking about how hot things are outside and looking at possible duct leaks, how hot is the attic air around your duct? Is the duct line well insulated? That attic oven might be warming the air before it gets out of your supply vents into the house. You may have other problems with the system, but in these temperatures you may have multiple battles at the same time.
 
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kms254

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i won't lie, the attic is hot, but at night its nowhere near as hot as during the day, i would say its about 80-85 at night in there. The lines are soft ~1.5 feet in diameter round lines that are insulated and the return that I am measuring at is no more then 2 feet from the unit in the attic, so there is not much room for it to be re heated.
 

Torque1st

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Thanks for your advice, How do you go about cleaning the A coil? Any products? I know what you mean about a good AC guy. I'm 24, and just bought this as my first house, it was built in 97 and the hvac stuff is original to the house, and probably not maintained much by the original owner. I one of my very good friends brothers is an HVAC guy and lives here so I am going to call him tonight. I would trust his opinion and I would not think he would screw me over.

The intake is in the middle of the house, and run by a 20' long 2-3' wide tube, I looked over its joints and i did not see any gapping holes or broken joints.

I open up the side of the evaporator and coil then use a small soft bristle brush. Brush with a good soft brush so you don't bend the fins. Catch all the crud with a vacuum.
 

copterdoctor

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I wouldn't do a thing.... I would call your warranty company and DEMAND them to come fix it.... i don't understand why you had to pay anything... isn't that what warranties are for???? how long did it take him to "clean" your filters??? anything special used? cuz i'd have done it myself, and made him watch, THEN have him RE-diagnose.... sounds like you're getting shafted.... good luck man...
 
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danski0224

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Did they bother checking superheat and subcooling?

Suction and head pressure mean nothing without those other numbers.

Same with a 20* difference between return and supply.

Rules of thumb will get you nowhere.
 
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kms254

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I wouldn't do a thing.... I would call your warranty company and DEMAND them to come fix it.... i don't understand why you had to pay anything... isn't that what warranties are for???? how long did it take him to "clean" your filters??? anything special used? cuz i'd have done it myself, and made him watch, THEN have him RE-diagnose.... sounds like you're getting shafted.... good luck man...

He sprayed a solution on the coils let it sit and hosed it off, i watched very carefully and this is what he used:

http://www.johnstonesupply.com/archive/tabid/1783/default.aspx?product_group=720

its about 15 bucks for a gallon, and a gallon will do 5 coils. So he had 3 dollars in materials.

He claimed he could not get a true reading with it being so dirty before he added the freon, or he could add to much and it would burn up the system. But his numbers before and after the cleaning were very very close, which makes me think the cleaning did nothing at all and that was his way to extort money out of me easily.
 

bazar01

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Your return air temp is 80F and supply air temp is 75F? Something wrong inside your evaporator section. You should be looking for at least a 15-20 degree drop.
With a 20 degree drop, your supply air at the vent should be 60F and as the return air temp drops so is the supply air temp.

Make sure the first stage electric strip relay is not stuck closed as the heat strip will warm the cold air that has just passed thru the coil.
A clamp on ammeter will tell you if the heat strip is ON. With just the evaporator fan running, your amp reading should be less than 5 amps. It the heat strip is ON, you will see more than 5 amps of draw.
Good luck.
 

rcayot

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I had a different experience with my HOW. when the unit started leaking water into the living room, I called the warranty company. They sent someone out. These two OLD red-necks from teh backwoods of Alabama came over in a beat-up Datsun pickup. I could hardly understand them when they spoke. They were ALL over my unit inside and out, cleaned up the drain that caused the leak, pressure tested the system and checked for leaks etc. Went back in to check conditioned air temp.

When they were leaving I got out my checkbook..... total cost was $47!!!????

They got a big chuckle over my experssion when they told me. They quipped:

"you thought we was gonna rip you off didn't you??"

They wer ea couple of GREAT old guys, just doing some odd jobs for teh insurance company...

Sometimes it pays to call the HOW company....
 

cowboyjosh

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Glad to hear some folks had good experiences with the HW companies. In the cities like Denver and Phoenix, some, not all of the contractors who work for the big name HW companies are your large service outfits that advertise on every TV and Radio station that pay their techs on a commission. I asked one HVAC tech who did work for one of my customers who grossly overcharged, charging like $1100 to replace a non programmable, electronic Honeywell thermostat and a furnace filter"how can you sleep at night you *****?" he told me "I have to bill $1450 dollars a day, if I don't I get fired" he then told me to eff off and hung up. My customer who I had built the house for 9 years prior, who are elderly called me AFTER they paid because they were fast talked by this fella and felt like they were ripped off, they were. I did finally recover $800 for the homeowners from that big name Denver HVAC service outfit that does HW work for AHS and Blue Ribbon.

I think in the so called "backwoods" areas and Small Town, USA God fearing folks are a whole lot more honest in some cases, knowing they are going to see you after the fact at Church, the hardware store, grocery store, etc.
 

seagravedriver

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I would never pay for one, as the one time I used it probably took a year off my life due to anger and frustration. The HVAC guy that fixed the fan motor worded it so they would pay for it. As far as getting a good HVAC guy, priceless. The joker that installed it in this house before I bought it put in an air handler that is an updraft unit when it required a downdraft. So he flipped it upside down. The tray and drain for the AC was cracked, got that fixed, they hooked up the drain wrong, got that fixed, now a year later I have a gallon + of water on the floor, as it is not draining again. Got a whole new unit coming in the next month or so. Some side work from a good friend. What a pain.
 
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kms254

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Ok per suggestions on this site, I took a look at my coil in the attic. I also checked the supply line and it was frozen over,

The upstairs coil looked like this:

35949_692265592306_26501048_37506428_4045143_n.jpg


Any Ideas?


The heatstrip you talk about is that in the compressor or the attic unit?
 
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csp

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Turn the AC off and let it thaw for starters.

I'm in a non-humid climate, so my next step probably isn't applicable.
 
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kms254

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I did that last night when I saw it, I read that leaving it running while iced over can cause more damage. I am planning on cleaning it today and looking at the blower motor.

I have never lived in a place with gas and we have a gas heater, if i pull the breaker to the hvac system do I need to turn the gas off? What controls the flow of that gas? Due to lack of knowledge/exposure I am fairly worried about gas leaks.
 

wbrian63

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No worries on the gas - it requires voltage to open the valve, so pulling the power will risk nothing.

Since you have gas heat - there's no heater strip as a previous poster noted.

You either have insufficient flow over the coil, or the unit is low on freon.

As for paying for cleaning the coil outside - home warranties cover things that break, not things that need servicing.

Don't be to hasty to assume the coil didn't need cleaning - with the freeze-up you're seeing, that will definitely have an impact on the pressures seen at the condensor.

The tech should have pulled the cover on the evaporator. That's a miss on his part...

There are 2 parts to A/C systems like this - the condensor coil/compressor and the evaporator coil/air-handler. "Fixing" or "servicing" an A/C by only working on the outside stuff is like saying you "serviced" the oil in a car by only changing the filter.
 

bazar01

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I did that last night when I saw it, I read that leaving it running while iced over can cause more damage. I am planning on cleaning it today and looking at the blower motor.

I have never lived in a place with gas and we have a gas heater, if i pull the breaker to the hvac system do I need to turn the gas off? What controls the flow of that gas? Due to lack of knowledge/exposure I am fairly worried about gas leaks.

Yes, leaving the whole system running will cause more damage. You need to go to your thermostat and put the COOL/OFF/HEAT switch in the OFF position, then put the fan AUTO/ON switch to ON position to keep the evap coil blower running to thaw the ice in the coil.

Due to lack knowledge of A/C system, you need to call an A/C service company. Your unit is low on charge. A knowledgeable service guy will charge the unit based on the system recommended superheat and subcooling information that can be found behind the electrical cover on your outside condensing unit.

Your unit has gas heat so disregard the electric heat strip being stuck ON.

With all the facts you have, you will be ready for the technician. Good luck.
 
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kms254

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Ok I might have not been super clear:

The service man came out earlier in the week, He suggested the cleaning of the outside compressors coil so he could get true reading on the pressures. I understand that maintenance is not part of the home warranty, I was skeptical of how dirty the compressors coils were(we had it inspected in march). At that point I decided to go ahead had have him clean the compressors coil, after the cleaning of the outside coil he added freon to get the system up to the proper specs(He said he added 1/2lbs and the system holds 7lbs). Not once did he go up into the attic and look at the evaporator coil. All of this work was done earlier in the week.

The picture I just posted picture was taken last night(about midnight), a good while after the additional freon was added, so I am going on the assumption that the service man knew what he was doing when adding the freon and we are at the correct levels.

Through research and my assumption I have come up with a hypothesis that i have insufficient flow over the coil. I have found that this scenario is most likely caused by some combination of two potential issues. One, the blower fan not moving sufficant air. This can be caused by a number of electrical or mechanical issues with the fan or the fan being clogged with dirt. Secondly the evaporative coil could be dirty, from my initial inspection and comparison to pictures online the non iced over part of my coil does not look extremely dirty, although a good cleaning could not hurt.

Since that photo was taken, I have set the thermostat to OFF and the fan is set to ON. My plan is to let the evaporative coil thaw out until i am off of work today and then clean the evaporator coil tonight. I am also planning on taking a look at the blower and make sure it is operating up to spec.
 

6768rogues

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You should have 25 or 30 degrees of temperature change across the coil, which will translate to about 20 degrees at the discharge/intake registers.
 

bazar01

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Ok I might have not been super clear:

The service man came out earlier in the week, He suggested the cleaning of the outside compressors coil so he could get true reading on the pressures. I understand that maintenance is not part of the home warranty, I was skeptical of how dirty the compressors coils were(we had it inspected in march). At that point I decided to go ahead had have him clean the compressors coil, after the cleaning of the outside coil he added freon to get the system up to the proper specs(He said he added 1/2lbs and the system holds 7lbs). Not once did he go up into the attic and look at the evaporator coil. All of this work was done earlier in the week.

The picture I just posted picture was taken last night(about midnight), a good while after the additional freon was added, so I am going on the assumption that the service man knew what he was doing when adding the freon and we are at the correct levels.

Through research and my assumption I have come up with a hypothesis that i have insufficient flow over the coil. I have found that this scenario is most likely caused by some combination of two potential issues. One, the blower fan not moving sufficant air. This can be caused by a number of electrical or mechanical issues with the fan or the fan being clogged with dirt. Secondly the evaporative coil could be dirty, from my initial inspection and comparison to pictures online the non iced over part of my coil does not look extremely dirty, although a good cleaning could not hurt.

Since that photo was taken, I have set the thermostat to OFF and the fan is set to ON. My plan is to let the evaporative coil thaw out until i am off of work today and then clean the evaporator coil tonight. I am also planning on taking a look at the blower and make sure it is operating up to spec.

If the tech recharged the system, we can assume he followed the superheat table, so the last suspect will be a plugged up evap coil cooling fins. You can try cleaning it with a non-rinse coil cleaner, but what we usually do is just pull the coil so we can clean the back side of the coil better. Pulling out the coil though is not an easy job for a homeowner with no HVAC tools.

Since your coil is in the attic, I can understand why the tech did not even bother to check it. It was probably at least 115F inside the attic.

Good luck.
 

BD1

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hi, you can use a blow dry hair drier or a heat gun to speed up the process of thawing. your pressures seem ok but the problem I think is that evap coil was still frozen or close to it when he did the charging. thaw out and see what happens. NO OPEN FLAME!!!!
 

Vettman

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make sure your not pulling attic air in with the return air..If the suction side of the air handler is in the middle of the house,It may not be sealed up from the attic...as in balloon construction...like the above comments, call your buddies and find you a reputable A C tech..self employed..
This was happening in my case. The return air is directly under a short coat closet in the middle of the home and next to a zero clearance fireplace chase(leading to the attic). The plywood return air plenum wasn't sealed well and it was drawing hot air from the atic. I sealed all the joints with silicone and plugged a 2" X 4" hole in the framing. Works much better now!
 
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kms254

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hi, you can use a blow dry hair drier or a heat gun to speed up the process of thawing. your pressures seem ok but the problem I think is that evap coil was still frozen or close to it when he did the charging. thaw out and see what happens. NO OPEN FLAME!!!!

Melting it is not a problem, it has been 100+ during the day here and I have let it thaw for a good while before the service man came, about 24 hours.

Well after letting it thaw, I cleaned the evaporator coil, basically taking apart the box around it to get good access and cleaning it really well. I put it all back together and sealed it back up. It did start cooling the house down a but, I think i had about a 10 degree difference between temperatures, but it ended up freezing again.
 

danski0224

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Is the blower wheel clean? A thin film of dirt has a huge impact on air movement.

Is the inlet side of the coil clean?

Filters clean?

FYI: an OVERCHARGE will do the same thing. Some "techs" charge till they get 70 PSIG on the low side. Pulled 9 extra pounds out of a system once.

If the compressor valves are shot, you will have low suction pressure, and possible coil freezing. Only way to know is to check superheat, subcooling and amp draw.

If the unit has been overcharged (low superheat if airflow is good), liquid gets back to the compressor, damaging it.

Frosty coil = low charge is not always correct.
 
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kms254

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The plower wheel was fairly hard to get to, but from what I could see it did not look very dirty. The outside coil, and the evaporator coil have both been cleaned. When I have the fan on the ON mode it does fee like its moving quite a bit of air, it does only seem like it has only one speed though. The home filter has been replaced a week or so ago(first step).
 
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