(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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1answer
18 views

HVAC breaker issue

My HVAC (Tempstar 5300XL) comes on automatically at the preset temperature. It may run cold for 45 minutes to an hour, then trips the breaker. What is the most logical problem, and solution?
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1answer
33 views

HVAC System Just Installed Yesterday and AC condenser outside is blowing cold ir

HI my just installed ac condenser is blowing cold air out side . when I put my hand over it and move it around most of the air is hot but a portion of it is cold. Is this right ?
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1answer
57 views

Help installing new thermostat

disclaimer, this is my first attempt at doing any type of electrical work, so apologies in advance for any wrong terminology :) I attempted to install a new Honeywell programmable thermostat. When I ...
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0answers
11 views

Goodman system stops running [on hold]

I have a Goodman electric heat & air system that was installed about a month ago I've had issues since then. I had a technician come out and he had it running fine then all of a sudden it stopped ...
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3answers
43 views

Problem- air condition- compressor and fan outside not on

I'm new to hvac. My ac was working fine but it decided to die one day. I've been able to fix my ac, but it continues to happen(the same problem), and it is not easy to get to the ac (it's on the ...
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1answer
39 views

Furnace is Sweating an Abnormal Amount

I noticed my furnace sweating a couple days ago. It's hot and humid where I live so I was only mildly concerned. It was a high of 74F today with humidity around 70% which is, relatively, nothing. ...
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0answers
23 views

Upstairs/downstairs cooling- leave it on or off?

It's 100+ here in Texas. My house has separate air conditioners for upstairs and downstairs. We rarely go upstairs, but I'm told that we have to account for air flow "chimney effect" up the stairway ...
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3answers
87 views

HVAC system that pulls-in cold air from outside?

My house has an existing forced-air heating system and I'm looking at getting central AC added in a few weeks' time (indeed, I've booked contractors for estimates next week). An AC system would keep ...
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0answers
22 views

Ac running but my blower will not

My ac unit stopped feed cold air from the unit outside. The main fan on top is spinning fine and my lines are freezing but the blower in the unit is just barely turning. Can someone tell me what would ...
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1answer
30 views

What could cause my Carrier furnace fan to sometimes stop running?

I have a Carrier system: FURNACE 58UVB080; AC 24APA530, CONTROLLER SYSTXCCUIDO1-B, approximately 7 years old. New filter, impeccable condition. I was initially told by the licensed installers that ...
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0answers
22 views

Older home with no AC plenum…replace our entire AC system as suggested?

We have an older home that has a large living-area/fireplace room; the AC unit sits over it in the attic. Earlier this year, in that room, we noticed a crack beginning to form in the ceiling sheet ...
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1answer
19 views

HVAC leaking cold air at unit: seal with tape?

I was in my crawlspace today and noticed that there was cold air leaking from a grouping of three round openings in my unit (pictured in the middle of the photo below). The outer two holes had rubber ...
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2answers
36 views

One portable air conditioner - want to use it in two rooms

I have a Kenmore portable air conditioner model - 408.72012. this particular model can be housed on the outside of the building and the A/C air is vented into the inside space (normally through a ...
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1answer
52 views

How can I determine the start up amps on a 3 phase 5 ton A/C unit?

I am trying to properly size a home generator and my concern is the start up amps on a 5 ton AC unit (15 years old R22 Goodwin type). My home power is unique because we have 3 phase (the AC is on 3 ...
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1answer
25 views

Can using a new evap coil on top of an older furnace cause problems?

I am getting quotes for a new R410A condenser unit/evaporator coil from several HVAC contractors. A salesperson refused to give me a quote unless I purchase a new furnace as well. He said that he has ...
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1answer
44 views

Can the A/C temperature through a vent be significantly lower than in the air handler?

Can the A/C temperature coming out a vent be significantly lower than the temperature in the air handler above the evaporator coil? If so, how does the air get colder as it comes out the vent? Or ...
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1answer
37 views

How can I prevent a secondary condensation drain line from dripping down the side of my house?

I have 2 central AC units in my 2 story house. From what I was told by the last AC repair man that visited, each of my ac units in the crawl space/attic has a main drain line that drains directly ...
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0answers
56 views

How to repair buckled duct work inside wall?

Background My house was built in the 1930s, I assume these ducts were installed when the home was built. This duct goes from the supply plenum in the basement to the 2nd floor master bedroom. The ...
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0answers
19 views

Goodman A/C unit sparks at high pressure line on furnace. Blows breaker

Got a 10 year old A/C unit and notice breaker blown. Flipped breaker and noticed a spark where the high side line goes into the plenum of the furnace and the breaker blew again. A/C repairman checked ...
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1answer
53 views

replace old furnace blower motor with a new one but the wires are different

It is an old Rheem RGAA-100C furnace, On the old motor the wires was: White, Brown, Red, Black and Blue. On the new Motor it has Brown, Brown/White, Black, Red, White, and Blue. I don't know how to ...
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1answer
53 views

Why would my house be so humid even when the A/C is running?

I live in Florida which this year has been particularly hot and humid. However, a while back I noticed mold in my closet and a very musty smell in my living room. Actually I even found mold growing on ...
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1answer
42 views

Water Heater Gas B-Vent Install

I installed a new water heater and want to vent it right. The old water heater used ABS pipe since it had a blower. Basically I have a 3" b gas vent pipe coming in and connecting to a flex gas pip ...
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1answer
44 views

Can dehumidification be achieved in a typical US residential forced-air system without dedicated components?

We have a very typical forced-air HVAC system with a medium-efficiency gas furnace and split-system central air conditioner in our house; however, latent load buildup (i.e. stickiness) is a problem ...
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1answer
35 views

Why would the condensing unit fan shut off but not the compressor?

We have an allegiance 12 unit circa 2001, model 7a2024a100a3, the fan starts up and runs for about 5 minutes then shuts off, the compressor is still on and seems to build up a bit the "flush" or so it ...
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0answers
28 views

Furnace not working

I came home to my furnace having no power even to show trouble codes. I turned off my breaker opened the blower door and it had a blown 5 amp fuse on the curcuit board. I replaced the fuse turned the ...
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2answers
40 views

2 PVC Pipes running from unit to basement

I have two 2" PVC pipes running from outside (AC unit) to the inside set up (furnace?). I need to cut these pipes and re run them since they are blocking the water heater which I need to take out. I ...
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1answer
40 views

Should I add a return or another supply to a large room with only one supply?

I just moved into a new house and I have that one room that always seems to be hot. It's on the 2nd floor of the house with the attic over it. The other 2 rooms on the 2nd floor are always a nice ...
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0answers
18 views

Why does my furnace blower motor stop working after 20 minutes?

The furnace blower motor stops working after 20 minutes, but the central air unit outside continues to run. The blower motor will not start again until after it has cooled off or unless I assist the ...
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1answer
30 views

Chattering contactor, what should voltage be when AC is on/off?

I have a Nest thermostat that I believe is the culprit of this issue. I've already replaced the contactor once and now the new one is chattering and not kicking the AC on. When the AC is turned off, ...
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0answers
37 views

What could cause a 5 ton Goodman packaged unit on the roof to turn on and off randomly?

With the thermostat on cool and manual the unit (fan + compressor) will turn on sometimes right away, and sometimes after hours. Then it'll run for either minutes or hours before turning off, either ...
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0answers
20 views

AC fan not turning on. It's silent

Replaced the capacitor 2 weeks ago because AC (Lennox) outside fan was not running, blowing in warm air. And the unit started working. Then again yesterday (95F outside) same thing. Replaced the ...
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2answers
490 views

Is there a way to turn on the air conditioning only on certain days?

We're looking for a way to turn on the air conditioning at our camp, say on a Thursday night, so that it will be cool when we arrive on Friday evening, but to shut it off if we don't go to the camp ...
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1answer
34 views

Closet where AC/Heater fan is located is very cold

I noticed that the closet where my heating unit/AC fan lives is super cold. I measured the temp using a black and decker IR thermal leak detector and the temp in the closet is about the same temp as ...
0
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1answer
48 views

Blower fan works w/ heat “auto”, not with a/c “auto” or on “on”

I've read the posts with the opposite issue, which have been helpful (you guys are amazing!) but still no solution. Problem is that the blower fan does not come on when system is on "Cool" and fan is ...
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0answers
35 views

Why would a blower motor work with A/C, but burn out with furnace?

I've gone through 2 blower motors since I purchased the home 3 yrs ago. I never have an issue with the blower when the AC runs; but it keeps dying in the winter with the furnace. I've had 2 HVAC ...
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1answer
59 views

Are my outside HVAC units and condensation drain PVC pipes set up correctly?

I'm a newbie with this stuff, but here's my situation: I have two HVAC units in my home. One sits on top of the patio and one sits on the ground. Both of them are draining condensation from the PVC ...
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2answers
65 views

Do I need an HVAC vent in this bathroom?

The finished portion of my basement was completed after the original construction. I've found a few questionable practices, including the lack of an HVAC vent in the basement bathroom (shown in green ...
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1answer
54 views

Why is there a supply vent in my unfinished basement?

Background I have an unfinished basement. It has cement floors with stone walls. The furnace is located in the basement. There is a supply vent blowing conditioned air into my basement. As far as I ...
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0answers
31 views

Why is ERV (return-return) installation not recommened?

I just had an ERV installed I was expecting the install to be return-return (ie indoor air from return duct pushed outside, and outside air pushed back into return further down the return). The ...
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3answers
62 views

Ac unit set on 74

My central air is set at 74. Yesterday and today, the house was up to 80. It has been very hot outside(90). Would this affect my ac unit?
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0answers
49 views

noisy Air-conditioner compressor

I bought a new split AC that worked great for a week or so, but now I can hear some annoying noise coming from the outdoor unit. The outdoor unit in installed on a flat roof so I can hear this noise ...
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2answers
60 views

Blower motor lost RPMs after reversal of fan direction

My air handler requires a clock wise rotation of the fan motor. After installing a new motor I found it was set in the counter clockwise position. I changed the wires (switched inline connection on ...
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0answers
19 views

How to connect honeywell wifi thermostat to trane A/C unit

My current system has 4 wires to the thermostat. I need to add the C wire for the new honeywell wifi thermostat. On the wiring board of the a/c I found 26vac on one terminal. The red wire to the ...
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6answers
770 views

Air Conditioner Can't Keep up

We just rented a condo and our A/C cannot keep up so it will run almost constantly. It can't even keep the temperature constant, it will creep up into the 80s even while running. I measured the ...
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0answers
31 views

Moved thermostat now ac wont turn on

So i was moving my thermostat to another room. I cut the wire to splice a new wire in. I got zapped first then spliced the wire. Now my thermostat is good to go but when it calls for the ac to kick on ...
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2answers
81 views

How can I wire my WIFI thermostat to control my millivolt fireplace?

I have a gas fireplace that has an millivolt on/off switch on my wall (and a remote that includes flame on/off, a countdown timer and a thermostatic flame control). I want to be able to program ...
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0answers
19 views

connecting into 24v on HVAC transformer [duplicate]

I've located available 24v to tap into on my transformer but what's the physical procedure to add my tstat wire for C?
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2answers
101 views

Do I need to level the outdoor AC cooling unit?

I've read somewhere that the outdoor AC unit needs to be leveled. My outdoor unit is a bit slanted due to the floor not being completely flat (pic below). However, I don't see any obvious structural ...
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0answers
74 views

Will a DIY Air Conditioner help my HVAC Central Air system?

So the husband and I just moved to Texas. We went away for the weekend and turned our HVAC central air from 68F and ON to 75F and AUTO. For some reason when we got home the AC wouldn't drop. Now I ...
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1answer
45 views

How can I better control temperature differences between floors in my two story home that has two HVAC systems?

We have 2600 sq ft on the main level and 800 on the 2nd floor. To the 2nd floor, there is a staircase and with a door on the bottom floor. We have our master upstairs and don't use the room at all ...