I know I am not vetted to post in the AOP section, so I am not posting advice, but did none of you notice this line from the OP. "110 outside.
Unit only runs during cheap electric rate time .....7pm til head off to work at 9am then we shut the unit off."
Unit is off for 10 hours a day, when it's 110 degrees outside. I would be happy with 79 degrees if I shut my unit off, half the day. Just wanted to point that out, delete if you must, but not posting advice, just stating the obvious.
Probably cutting out on high pressure due to dirty condenser coil.Need subcooling and superheat
The unit runs all weekend and does not cool below 79 when set at 70.
The small unit on the master side runs the same and cools like a champ, so what is wrong with the big a/c unit?
"Proper freon level"...easy to say, harder to verify. Anyone who says "freon level is proper" going ONLY by what he reads on his gauges...chances are very high the refrigerant level is not "proper". Superheat and subcooling: bare essentials to understanding practical refrigeration.
I have put my gauges on systems where the pressures "looked normal" by the seat-of-my-pants observation, but in reality the system was several pounds overcharged. After pulling out that much gas, the gauge pressures did not change much, but the superheat and subcooling numbers certainly did!
- Electricity makes refrigeration happen.
- Refrigeration makes the HVAC psychrometric process happen.
- HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.
A building is NOT beautiful unless it is also comfortable.
tech put in freon the first visit and it worked for awhile and then stopped cooling.
2nd tech too much freon and removed it and said next time it happens tell tech to go in the attic to the attic unit and replace the 240 volt capacitor and sequencer but the 3rd tech only checked the freon and said nothing is wrong.
2 hours from now a new company tech is checking the unit and hopefully knows what he is doing with an a/c unit that keeps loosing freon and doesn't blow enough cold air.
You're going to have a lot of money spent on calling Techs without them checking what needs to be checked; so I think we need to help You, with your help, with a ballpark analysis of your system's functioning levels.
Originally Posted by mjbl
Want us to be enabled to check the ballpark performance of your system... so you can call an HVAC Contractor with some hard data showing what needs servicing?
All U need is a good thermometer (digital reading in tenths preferable) & and indoor Humidity Gauge
1) Helpful; Tonnage & SEER of Unit &/or outdoor condenser model number: __________________
2) TXV or, orifice metering device? _______. Only if U know…
3) Outdoor condenser’s discharge-air-temperature ______-F
Subtract Outdoor air temperature: _______
Outdoor Condenser Air-Temp-Split _______
4) Need the ‘Indoor’ percent of relative humidity - in the middle of the rooms or, at Return-Air inlet grilles ___
5) Indoor Return-Air Temperature ______
Subtract Indoor Supply-Air Temperature ______ -F
Indoor temperature-split _______-F
If U can find a turn in the small liquid line insulate the temperature-probe; get its temperature for the subcooling analysis:
Small liquid line temperature ____F
To measure return air the wet bulb temp, wrap a small/thin, wet (not dripping) piece of cloth around the probe and put it into the Return Air grille & then close to the closest Supply Air diffuser near the air handler (need air movement). Wait until the temperature stabilizes - may take a little while.
Return Air wet bulb ____F
Supply Air Wet Bulb ____F
Need the above information for troubleshooting & performance analysis.
A Goodman 2-Ton 13-SEER condenser, @800-cfm indoor airflow; 80-F indoor dry bulb & 50% relative humidity; Indoor temp-split 18 to 19-F.
@ 85-F outdoors; 103.9-F - 85-F outdoors or around an 18.9-F temp-split;
@Indoor 75-F, 63-wet bulb around 50% RH - condenser temp-split is only 14.9F.
Below is helpful - A Tech needs to do this:
Indoor Total-ESP - External Static Pressure ______
You or Tech- All Supply Air velocities in FPM: ______
Measure supply-register’s, louvered areas _______
I'll do the math for the total CFM ______
A Tech- Suction line pressure _____
Suction-Vapor line temperature: ______
A Tech- Saturated Suction Temp – Gage - Suction Saturated Temperature. ____
Tech- Superheat ______
Tech- Head pressure _______
Tech- SCT – Gage - Saturated Condensing Temp _______
Tech or you- Small Liquid line - temperature: _______
You/me- Subcooling: _______
Return Air temp Dry Bulb &, Wet Bulb & %RH: _______
Tech- Supply Air temp DB, WB &/or %RH to convert: _______
With Supply Air & Return Air Wet Bulb temperatures plus CFM
I can use an enthalpy chart to provide the Btuh output of the system
4th tech arrived today, unit running outside and going on and off inside.
Frozen outside and in the attic.
Ordered a new board and capacitor for the Goodman in the attic.
Will return with board and see if there are other issues like freon leak or???
ok, so on the Goodman unit in the attic the Burnace control board was replaced, replaced blower run cap and installed condensate safety switch, test ran system, Freon levels were proper after 20 minutes or more of running and air coming out of vents was 20 cooler than intake air.
Will it continue to cool tonite? I hope so but what I noticed on the Digital 7 day thermostat that is the original equipment when you have the unit fan on Auto and unit ton COOL and then press the present temp setting at the bottom of the number displayed SOME times it say HEAT and some times it says COOL if I try it several times. Does that indicate a Thermostat issue too?
$$$$ later this is getting expensive!!!
Last edited by jpsmith1cm; 08-09-2012 at 09:35 PM.
Pricing isn't permitted here.
I edited your post.
Is this a touch screen stat? It may be from pressure on stat. I don't think your supposed to have prices. All areas have different rates, one guy might think you got screwed and another might think the price is on track, pretty soon your freaking out and pissed off. Not good
oops typo, it was called a furnace control board
oops sorry, didn't mean to offend.