Home A/C help! Guru needed...

**chuckie669** · 06-29-2009, 05:29 PM

I know this isn't a house forum, but I could really use some help. I have two young girls and can't afford to have my house so hot. I tried calling and should have someone out on Fri/Saturday. Okay, here goes the novel...

I have an outdoor A/C unit, new attic unit and all new ducting along with a digital thermostat put in about 2 1/2 years ago. Been trying to change the filters about every 30-60 days along with running some bleach down the overflow to keep it from backing up.

within the past two weeks I've been noticing that the digital thermostat will be set at a temp, but the actual temp it's reading is much higher (set to 73 actual temp 78-79 and climbing. I have a newborn and probably haven't changed the filters in three months. The guy told me that filter was probably dirty causing the attic condensor to freeze up. He said to turn off the unit and run the fan on "ON" for an hour or so, then try to turn the Air conditioner back on.

So I turn it off and just run the fan. The house starts to cool off which I thought might be due to the freezing coil thawing? I fell asleep and woke up the next morning to a house that was 68 degrees with the A/C off and only fan set to on. this happened again yesterday and once again, this morning it was 68 again. tonight when I got home, yep 79 degrees again.

Does anybody know what would cause the unit to be cooling the house when the a/c is set to off an the fans are set to manual on? I noticed that both the attic vent fan and then outside blower are both running when I have it on Manual On fan. Could this be something with the digital thermostat?

**Zboner** · 06-29-2009, 05:32 PM

its the thermostat most likely, i have put some on and the next day they are bad. what kind of stat is it man? a programable stat? or just one with the options of heat/cool then fan-on/auto?

**Zboner** · 06-29-2009, 05:33 PM

or could simply be the anticipator setting on the stat which might be off also.

is the outside compressor running when cool is off? and you just have the fan set to on?

**chuckie669** · 06-29-2009, 05:37 PM

It's programmable. Pic just taken below. sofar it's dropped one degree.

EDIT: wow, that was a shitty pic...

**Zboner** · 06-29-2009, 05:39 PM

there is a possibility that someone messed with the settings? kind sounds that way to me. so set it to off and the fan on auto what does it do? does the compressor run still to the outside unit?

**chuckie669** · 06-29-2009, 05:39 PM

Originally Posted by Zboner

or could simply be the anticipator setting on the stat which might be off also.

is the outside compressor running when cool is off? and you just have the fan set to on?

Yes, the outside unit is running and the fan out there is blowing warm air. Up in the attic there is also a fan blowing, which I'm guessing vents out to the roof?

**chuckie669** · 06-29-2009, 05:43 PM

Originally Posted by Zboner

there is a possibility that someone messed with the settings? kind sounds that way to me. so set it to off and the fan on auto what does it do? does the compressor run still to the outside unit?

Changed the fan to auto and left the ac off. After about a minute, I heard the suction cut off on the filter and walked outside. Outside unit was off also.

**Zboner** · 06-29-2009, 05:44 PM

ok well just try and switch it with the fan on auto and the setting to cool, also you can use your programable stat just like a normal thermostat and you dont have to fool with all the settings.

**cammed goat** · 06-29-2009, 05:45 PM

Man, I wish I could remember my HVAC apprenticeship days.

**Zboner** · 06-29-2009, 05:46 PM

Originally Posted by chuckie669

Yes, the outside unit is running and the fan out there is blowing warm air. Up in the attic there is also a fan blowing, which I'm guessing vents out to the roof?

im sure up stairs you have 2 pvc pipes running out the roof or the side? or do you have a heatpump? if you have a heat pump your main source for heat/cool is from the outside unit.

is the big copper line cold?

**Zboner** · 06-29-2009, 05:47 PM

Originally Posted by cammed goat

Man, I wish I could remember my HVAC apprenticeship days.

lol, been there and do it every day even though i dont have my license still

**RyanKDE** · 06-29-2009, 05:50 PM

Hey Chuckie, I'm an hvac service tech and it sounds like your evaporator coil in the attic may be freezing up due to a low freon charge. Have someone check the charge in the a/c system. If it freezes up it won't cool the house and when you shut it off it will melt the ice. Combine that with the cooler night temps and it will drop the house temp. During the day it can't keep up because the charge is low, and that will freeze up an evaporator coil.

**chuckie669** · 06-29-2009, 05:51 PM

Originally Posted by Zboner

im sure up stairs you have 2 pvc pipes running out the roof or the side? or do you have a heatpump? if you have a heat pump your main source for heat/cool is from the outside unit.

is the big copper line cold?

Line was cold. I keep the ac set to cold and the fan to auto. It gets warmer. I just set it back to off and fan on, and can seriously feel cooler air coming out of the vent. I also tried replacing the battery in the thermostat and can't tell any difference.

**Zboner** · 06-29-2009, 05:55 PM

yea the battery in the stat is nothing it is getting 24volts from the furnace, dude ok it sounds like its the stat i would honestly start there and if its not the stat its the board which is expensive as hell, but you said its a new furnace you should have a 3 year warrenty on parts all you have to do is pay for labor.

if i was closer i would run down and try and figure it out, i just put in an a/c unit friday man.

**cammed goat** · 06-29-2009, 05:56 PM

Originally Posted by Zboner

lol, been there and do it every day even though i dont have my license still

That sh1t was fun...the layoffs...not so much.

**Zboner** · 06-29-2009, 05:57 PM

Originally Posted by chuckie669

Line was cold. I keep the ac set to cold and the fan to auto. It gets warmer. I just set it back to off and fan on, and can seriously feel cooler air coming out of the vent. I also tried replacing the battery in the thermostat and can't tell any difference.

ok do you have a heatpump? well are you all electric? no gas? if so the reversing valve could be taking a dump on you.

**Zboner** · 06-29-2009, 05:58 PM

Originally Posted by cammed goat

That sh1t was fun...the layoffs...not so much.

yup but side work is bad ass, i just put in a new outdoor unit and indoor a coil last weekend and only charged the dude 2,500 for it, hell materials was only like 1,200 so i made bout 1,300 on it in 5 hours. win win for both of us.

**cammed goat** · 06-29-2009, 06:11 PM

Originally Posted by Zboner

yup but side work is bad ass, i just put in a new outdoor unit and indoor a coil last weekend and only charged the dude 2,500 for it, hell materials was only like 1,200 so i made bout 1,300 on it in 5 hours. win win for both of us.

That IS good. It's like a puzzle. Put all the pieces together and connect the wires. Then the moment of truth: flicking the switch and hearing the whirrr of the unit coming to life. Total win right there. Was quite gratifying.

**chuckie669** · 06-29-2009, 07:02 PM

I think it's gas/electric. I do have a gas line that runs to it in the attic, but can't tell you for sure if it's just for the furnace.

I've had the fan running for a few hours now and still 77 in the house. i'm going to set the a/c back to 74 and fans to auto and crash for the night. Guess I'll see if it keeps cooling down tonight.

The part of the puzzle that I hate is where everything looks like it works, but doesn't.

Thanks Zboner

**0rion** · 06-29-2009, 11:26 PM

t-stat's are cheap. I would get rid of that digital stat and just go with a regular t-stat for $14 or whatever they cost. I'm no a/c guy but I've worked on my POS more than once.

Might just try swapping that stat and see if that works.....cheap test and they're easy to install.