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Questions tagged [central-air]

For questions regarding a central cooling system for your home. This is typically a split system with an outdoor compressor/condenser and an indoor evaporator and air handler. Air ducts are used to cool air throughout the home.

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Determine specs / part info for AC contactor?

I recently asked a question about my AC unit not working properly, and I determined it's a faulty contactor. However, I cannot figure out what replacement contactor to get. The unit is 30 years old, ...
theforestecologist's user avatar
2 votes
1 answer
215 views

Tolerance for LRA and other settings on my AC unit from those on the nameplate?

tl;dr - How close to the compressor LRA / RLA and fan motor FLA should the meter readings be compared to the values on the plate? Do you also need to consider if multiple readings are off or too far ...
HelpEric's user avatar
  • 633
3 votes
2 answers
331 views

Central A/C system: compressor froze, refrigerant lines sweating through insulation, outside fan won't shut off

The story We noticed the outdoor AC unit was running (i.e., fan was spinning) nonstop for > 18 hours and was relatively louder than usual -- there is now a humming vibration that can be heard ...
theforestecologist's user avatar
0 votes
1 answer
43 views

Keeping AC P-trap clean with a Jones valve?

We recently had a new AC system installed. It's working great. When it was installed, the company showed me how they installed a Supco Jones Valve for cleanouts if ever necessary, and explained that ...
aggieNick02's user avatar
1 vote
1 answer
52 views

Where to install UV light in attic ductwork

Question is do they install it in line after the air handler? in which case it looks difficult to replace. Or is it installed before, near the intake 4 inch filter, in which case it looks easier to ...
Maesumi's user avatar
  • 681
0 votes
1 answer
59 views

Two 40uF to equal 80uF capacitor for AC unit

BACKGROUND: I bought a place that has an older Armstrong Concept 1200; I know nothing about it other than the fact that the unit ran fine last year; winter came, and I disconnected the power for ...
Charlie's user avatar
1 vote
1 answer
104 views

How to determine the proper capacitor for my air conditioner unit? Tech claimed the one installed is wrong

tl;dr - What should I be searching for in documentation to find the correct capacitor for my outdoor AC unit or what inputs do I use to calculate the appropriate capacitor? My AC has an intermittent ...
HelpEric's user avatar
  • 633
0 votes
0 answers
78 views

Where should I install duct take-offs on a return plenum box?

I have a 5-ton system. My goal is to add an 8" return duct to a 15x9 guest room that has an 8" supply but no return air. When I went up to the attic to review my options, I saw that the ...
yayza's user avatar
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0 votes
0 answers
38 views

Won't the secondary condensate p trap evaporate?

So my understanding is that both the primary and secondary condensate drain lines should have p traps installed to prevent air ingress (or egress depending of it's a positive or negative air system). ...
James's user avatar
  • 357
0 votes
0 answers
143 views

AC blowing hot air. Smart thermostat wiring wrong or something else?

I installed a Honeywell Wi-Fi smart color 7 day programmable thermostat (model #RTH9585WF) on 11/27/23. The wiring directions on it didn't exactly match my old thermostat so I posted on a forum and ...
Derek Gilbert's user avatar
2 votes
2 answers
829 views

Troubleshooting Lennox furnace error code E228 -- failed to calibrate pressure switch

I have a 90% efficient Lennox furnace, pictured below. Last night the heat stopped working. It actually had stopped working maybe a couple days ago too, but it fixed itself after a few minutes--I ...
Rodrigo's user avatar
  • 143
0 votes
1 answer
62 views

Is my furnace undersized? [closed]

I have a GMVC95070CX4 furnace. Currently, it is extremely cold weather (outdoor temp. -17). I have been experiencing poor heating and overnight . My house is 2975 sq ft. and I have a 5 ton AC system ...
Joshua K's user avatar
0 votes
1 answer
114 views

Are my condensate drain pain and p trap installed correctly?

Long story short, previous owner of my condo said the condensate overflowed into the ceiling. The building inspector suggested having an exterior drain pan installed. After move-in, I hired an HVAC ...
James's user avatar
  • 357
0 votes
1 answer
123 views

Can a heat pump designed for mini-split system be used for central AC ductwork?

I am looking at replacing my old central AC unit with a heat pump one using existing ductwork. A contractor quoted me Fujitsu Airstage indoor unit AMUG48LMAS with outdoor unit AOUG48LMAS1. I checked ...
ahala's user avatar
  • 103
1 vote
1 answer
53 views

Air register solution for this spot in the kitchen paneling?

We have this spot under our kitchen sink where there's a spot for the HVAC system to push air into the kitchen. The black item to the far left is our dishwasher. I believe these are IKEA kitchen ...
gammapoint's user avatar
0 votes
0 answers
2k views

Air conditioner outside unit / condenser does not come on when thermostat calls intermittently / usually works after switching break/pulling fuse

A few times over the past two weeks, my central AC unit would stop producing cool air. The inside fan (furnace blower?) would be working, but since the fan on the outside condenser was not running it ...
HelpEric's user avatar
  • 633
1 vote
2 answers
48 views

HVAC question about Evaporator Coil repair

My evaporator coil was recently replaced (Carrier CNPHP6024ALAAAAA replaced with a bigger unit, CVPMA6124XMC). They sealed around the edges with tape. The original install was sealed with some kind of ...
amrog's user avatar
  • 347
0 votes
2 answers
385 views

HVAC condenser fan overheating/shutting down turns out a bad control board

Two weeks ago my condenser fan started overheating after 15 to 30 minutes of runtime. Seeing as capacitors are cheap I replace the capacitor first. The problem persisted so I ordered a new fan motor. ...
Richard 's user avatar
0 votes
2 answers
577 views

How do I add central AC to my existing central heat system?

We currently have central heating. The unit is in the attic. The duct work is also in the attic. How would I go about adding central AC to my existing setup? How would I go about doing this my self?...
milesmeow's user avatar
  • 5,106
0 votes
2 answers
208 views

Why is my house getting warmer despite the A/C running?

Temperatures in my house have been climbing despite the A/C running. My condenser unit is running, appears clean, and no brush is growing against it. The pipe into the ductwork above the heater is ...
WantToDoItMyself's user avatar
0 votes
0 answers
41 views

vent damper looking for lever

I have attached a image of a vent we have in the house. I like to know if this has a damper I can adjust? I don’t see anything where there is a lever to turn? Any help would be great.
Jefferson's user avatar
  • 121
0 votes
1 answer
1k views

Condensate pump making loud noise

Attached to my furnace, there is a Beckett CB151UL condense pump. After every cycle of the furnace (either heat or cold) the pump, removes water from itself. It has started doing a loud whining/...
gmalenko's user avatar
0 votes
0 answers
25 views

Furnace Fan Only Turns On With Heat

Recently had a mini split installed, and the HVAC tech recommended that I occasionally turn on the fan to circulate cold air throughout the house. Tech changed the thermostat to a Honeywell Prestige ...
Andrew's user avatar
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1 vote
0 answers
212 views

Should my air conditioner be running its air directly through internal spaces?

Should a newly installed “ducted” split system be running its intake air directly through internal spaces, or should I demand that the system be sealed so that it only draws air from living spaces? I’...
Alex Peters's user avatar
0 votes
4 answers
2k views

Leaving second floor window open while running central AC [closed]

We know that windows should be closed while running the AC, but since the central AC and thermostat of my house is on the first floor, I was wondering whether leaving the window open decreases the ...
user2233706's user avatar
1 vote
1 answer
66 views

Two Identical A/C Units with Different Readings / Pressures not Stabilizing When Off

I have two separate systems with one in the basement servicing the main floor, and the other in the attic servicing the upstairs. The upstairs has been struggling in 90F heat ever since we moved in ...
JSess's user avatar
  • 185
6 votes
5 answers
1k views

Optimizing HVAC airflow for cooling

Here's the deal: Two-story c. 2000 house in southern Missouri, lower level is a "walk-out basement" (subterranean on 3 sides) and consistently 10 degrees colder then the main level year-...
Jamesfo's user avatar
  • 163
0 votes
1 answer
163 views

HVAC unit upgraded, contractor cut a new return in the oddest spot

My old HVAC system suffered damage due to a lightning strike. I called up a local service co. and they sold me on a Trane split-system that was slightly oversized compared to what we had. The new ...
Jamesfo's user avatar
  • 163
10 votes
7 answers
10k views

Why is my air conditioner causing rapid high CO2 levels?

I am wondering if anyone knows why when I turn my recently installed high-efficiency air conditioner on, CO2 levels rocket up in my house? (In just 4 hours they go from around 500ppm to 1200ppm, and ...
Adam Lopez's user avatar
1 vote
2 answers
161 views

How do I seal leaky air ducts?

I have duct work in a house that I recently bought were it looks like some ducts were removed and then just sealed over with a metal sheet. The vent seems to be leaking air and in my opinion should be ...
Collin Witt's user avatar
1 vote
1 answer
166 views

Why is my HVAC return duct near ceiling next to supply duct? [closed]

I've owned this home for about a year and this has always intrigued me. My 2-story home has a supply duct nearly pointing at a return duct in the center of the hall upstairs. Two questions: Would hot ...
JSess's user avatar
  • 185
0 votes
1 answer
1k views

How can I prevent fiberglass duct insulation from being blown into my living space?

For no explainable reasons (there are other materials that are not health hazard which provide sound insulation), manufacturers put fiberglass in the register boxes. I moved into a new, old, apartment....
atapaka's user avatar
  • 111
0 votes
0 answers
338 views

Cold air blows through supply vent when furnace is off

I have separate units for 2 floors. On 2nd floor , out of 3 room and big loft area only 2 rooms are always cold (like 55 degree during winter) when doors are closed. These rooms have 2 supply vents ...
Raja's user avatar
  • 1
0 votes
3 answers
1k views

HVAC air filter replacement interval in hours?

My condo has a central heat pump AC/heater system that takes a 20x30x1 air filter. My area is a very mild climate and the HVAC system rarely gets run. Checking my usage data over the past 12 months, ...
James's user avatar
  • 357
0 votes
0 answers
39 views

Forced Air Unit will not go off

My forced air unit never goes off. It comes on intermittingly all day and night. I have a FAU switch in my breaker box and I have turned it off, but the forced air unit still runs day and night. I ...
GBrown's user avatar
  • 1
0 votes
1 answer
2k views

How to fix a crushed A/C duct

One of my kids got into the attic and walked all over my 7" aluminum (?) round ducts. See the picture below. I found this post, but that's a different type of duct. My idea is to drill a hole and ...
Wynne's user avatar
  • 1,541
0 votes
1 answer
2k views

Cold air coming out from intake after A/C turns off

When my A/C compressor turns off, the air handler seems to go into an almost idle state where it still sounds like it’s on but not running on full power. During this time, cold air is constantly ...
blizz's user avatar
  • 101
2 votes
1 answer
2k views

Is it possible to adapt round HVAC diffusers to square?

I am working on a remodel in my older home. Currently all of the HVAC is run through sheet metal ceiling ducts, most of which are 8" diameter, and then when they reach the rooms, flair out to a ...
Jonathan Fry's user avatar
0 votes
1 answer
108 views

Carrier HVAC System with Variable Speed Motor burned out after 6 months

I just recently purchased a Carrier Hvac 3 ton heat pump system back in February of this year. The heat pump has a variable speed fan that just burned out. Is this common? This is a new system and it ...
Dan Pollack's user avatar
0 votes
0 answers
48 views

Single or two-stage replacement in two zone system

Need to replace an 18 year old single stage, two zoned furnace/AC installed in my converted attic in Chicago. It's in the knee wall and serves the attic and the second floor. Air returns on both ...
Peter Mazarakos's user avatar
0 votes
2 answers
136 views

Should registers have gray duct sealant

Should the internals of a register where connections are made have gray duct sealant?
Envieddesigns's user avatar
0 votes
2 answers
556 views

Why would part of my second floor not have any HVAC airflow?

I recently moved into a townhouse and found that on the 2nd floor, 2 rooms and bath doen't have airflow at all( no ac or heating). First tried with insurance company guys and he removed 1 damper which ...
Chandra Maral's user avatar
0 votes
2 answers
226 views

Low refrigerant pressure on AC - tech recommends replacing evaporator coil?

So this is a follow-up to my previous AC tech horror story: Rust on outdoor ac fan motor? Tech recommends replacement? . I got a new AC tech from a small two-tech company with glowing reviews, hoping ...
aggieNick02's user avatar
0 votes
3 answers
2k views

Does a heat pump have separate unit for heating?

I’m trying to upgrade my current HVAC system. It is a huge unit that looks like this: I went to the crawl space and I saw some flexible ducts that go to a duct that goes inside the house. So I assume ...
CuriousPaul's user avatar
1 vote
1 answer
2k views

Our AC isn't cooling to the set temperature

Our AC isn't cooling to the set temperature. We got one tech from Company-A to come and he said that the Freon is a bit low. So, on hot days, they can't keep up. But our unit has an older R22 Freon, ...
Naresh's user avatar
  • 11
1 vote
1 answer
1k views

How to measure current draw of AC condenser fan motor, single phase?

This question is a follow-up from a related question about an AC tech recommending a likely unnecessary fan motor replacement. See Rust on outdoor ac fan motor? Tech recommends replacement? I'm trying ...
aggieNick02's user avatar
4 votes
2 answers
3k views

Rust on outdoor ac fan motor? Tech recommends replacement?

I had my annual ac inspection. House has two units and one runs about twice as long each day as the other because it cools much more of the house, and had its capacitor fail two years ago. Tech ...
aggieNick02's user avatar
1 vote
0 answers
284 views

Identifying VOC sources

I have been racking my brain and searching google to try and figure out the source of the VOCs in my house. I've discovered a few, but they don't quite make sense to me and I'm still confused as to ...
Breedly's user avatar
  • 195
-2 votes
1 answer
46 views

Pump to push inverter A/C dripping water?

I live on the top floor of the building and my bedroom has an inverter A/C that naturally drips water to the street. The bedroom has access to the roof. Is there some inexpensive pump that will push ...
rbhat's user avatar
  • 2,083
-1 votes
1 answer
935 views

Possible to "soundproof"/reduce noise from First Floor Furnace/AC?

We have a 1080 sq. ft., 1-floor (no basement) house. Our furnace and cold air/AC returns/registers are literally almost in the living room/main sitting area and it's very loud year round, making for a ...
alxmntrvl's user avatar
  • 119

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