AC not working - not cold around furnace


  #1  
Old 07-05-19, 03:06 PM
S
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
AC not working - not cold around furnace

Hi!
So I tried to use my AC a few days ago. I switched my thermostat to 'Cool', and after a little bit I heard it click on.
Outside fan works. I changed my furnace filter 2 weeks ago.

No cold air from vents. I went down to the furnace, and the metal that usually gets cold is not cold. I do not see ice anywhere.
Could this be due to low refrigerant? Capacitor? Bad coils?

Thanks!
 
  #2  
Old 07-05-19, 05:47 PM
R
Member
Join Date: Oct 2016
Posts: 2,416
Received 178 Likes on 164 Posts
Is the compressor running? There should never be ice. Thatís a sign of problems.
 
  #3  
Old 07-05-19, 10:17 PM
S
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
How can i tell if i have a bad compressor?

The outside fan runs.
 
  #4  
Old 07-05-19, 10:55 PM
R
Member
Join Date: Oct 2016
Posts: 2,416
Received 178 Likes on 164 Posts
Not a ďbadĒ compressor, we havenít concluded whatís going on yet.
Is the compressor running at all?
 
  #5  
Old 07-05-19, 11:28 PM
S
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Sorry, this is all new to me. I meant how can I tell if the compressor is running?
 
  #6  
Old 07-05-19, 11:38 PM
R
Member
Join Date: Oct 2016
Posts: 2,416
Received 178 Likes on 164 Posts
You can usually here it.
It the contactor pulled in? Compressor pulling amperage?
 
  #7  
Old 07-05-19, 11:41 PM
S
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
I do not know what the contactor is.

I haven't chcked amperage on the compressor.
I can look into doing those tomorrow.

would a capacitor be an issue, even though the outside fan is running?

Someone told me to clean my coils, the ones in the furnace.
 
  #8  
Old 07-06-19, 06:01 AM
R
Member
Join Date: Oct 2016
Posts: 2,416
Received 178 Likes on 164 Posts
If the compressor isn’t running, cleaning coils will not fix the problem.
The contractor is in the condenser.
Do you have a meter to do electrical testing? Are you ok working with live high voltage?
It’s possible only one side of the capacitor is the problem. Or you may have 2 single capacitors.
 
  #9  
Old 07-06-19, 10:02 AM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,754
Received 56 Likes on 48 Posts
Yes, it's possible you have a bad capacitor. Most systems use either a dual capacitor (2 capacitors in one "can"), or two separate capacitors. One is for the fan, the other is for the compressor. If the compressor capacitor is bad, it could prevent the compressor from starting.

The contactor is a relay in the outside unit. When the thermostat calls for cooling, it sends 24VAC to the contactor coil, which pulls down the contacts, sending the 240VAC to the compressor and fan. Since the fan is running, the contactor is probably okay, however you can't say for sure without checking for 240VAC on the "output" side of the contactor, usually labeled T1 & T2.
 
  #10  
Old 07-06-19, 11:45 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,617
Received 157 Likes on 143 Posts
Hi, if you go out to the condenser there will be 2 copper pipes, the large one should be cold and sweating if the compressor is running correctly, donít get hung up on capacitors until you see what is working , is the inside blower running?
Geo
 
  #11  
Old 07-09-19, 09:30 PM
S
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Thanks all. Been away a few days, but thanks for all the great info!
I will check if the copper pipes outside are cold tomorrow. one i believe is covered in foam.(not gonna shock myself? do I need to cut power to touch the pipes?)
The one exposed copper pipe inside did not get cool when I was running the ac. didn't check the one inside covered in foam, safe to do so?

by inside blower, do u mean the main fan that sends air throughout the house (there isn't a separate ac fan, is there?)?
That main blower fan is running. actually running 24/7, some guy that worked on my system said it's designed to, although i have heard to put on auto for when ac is running.

So if the coils outside are not cold next could be the capacitor? The grey box outside that has fuses, could one be blown that would affect the cold air but not the fan (outside fan)? My dad can work with electrical stuff, not me so much, and he has the meter!
 
  #12  
Old 07-10-19, 05:22 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,617
Received 157 Likes on 143 Posts
No danger touching the the copper pipes, pull the insulation back a bit and see if its sweating.
Geo
 
  #13  
Old 07-10-19, 05:34 AM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,754
Received 56 Likes on 48 Posts
The foam covering the larger diameter copper pipe is insulation to minimize condensation on the pipe. No danger of getting a shock.

Yes, by "blower" we are referring to the inside fan that distributes air to the rooms. We often use the term blower to distinguish the inside fan from the condenser fan on the outside unit.

You mentioned in your original post that the fan on the outside unit is running. Does it go off if you turn off the thermostat? If so, the contactor (relay) is probably working okay. The best way to tell if the contactor and fuses are working correctly is to measure the voltage between the T1 & T2 terminals on the contactor. When the thermostat is calling for cooling, you should measure 240VAC. When the thermostat is NOT calling for cooling, you should measure 0VAC.

Assuming that you have 240VAC across T1 & T2 when calling for cooling, the condenser fan is running, but the compressor is not, there are 2 things you can check. First, turn off the power to the outside unit (grey box outside with fuses). Check the three wires where they go into the compressor (wear safety glasses when doing this). If you have a loose connection, one or more of the wires could be burned where they attach to the compressor.

If the compressor wires look okay, you could try buying a new capacitor. Many systems use dual capacitors, where one side is for the compressor while the other side is for the condenser fan. Capacitors are relatively inexpensive and is something you can easily replace yourself. Just make sure that the MFD values of the new capacitor are the same as the current one and the voltage rating is the same or higher. If the capacitor doesn't solve the problem, you'll have to call in a technician.
 
  #14  
Old 07-13-19, 11:17 AM
S
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Well, thanks so much all for all the great info! I've learned so much about ACs.

Had a friend's semi-retired handyman-type guy (sold his business, AC/furnace, etc) come by to take a look.

Hooked up the gauges and immediately saw i was very low on freon (older system). Topped it up and it's working fine now.
I know this is a temp fix, as there must be a leak somewhere. I am hoping i can get through the summer with this (in Toronto area, so I'll prob only need the AC till mid Sept.). I'll eventually get my system checked for the leak early next year.
Hopefully I am not back posting that all the refrigerant leaked out in a day

Thanks again all!
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: