AC not working


  #1  
Old 05-18-15, 03:37 PM
S
Member
Thread Starter
Join Date: May 2015
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
AC not working

Over the winter I installed a new thermostat. Everything went fine and the heat was working great. Now that it is summer time and it is time to turn on the air... it does not seem to work. It did work last summer, so I dont think there is anything wrong besides my wiring. Can you let me know what you see is wrong?

Name:  Furnace.jpg
Views: 273
Size:  32.9 KBName:  T-Stat.jpg
Views: 235
Size:  28.9 KB
 
  #2  
Old 05-18-15, 03:45 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,654
Received 90 Upvotes on 79 Posts
The Y terminal is the "control" line for the compressor/condenser (outdoor) unit. There should be 24VAC between the Y terminal and the C terminal when the thermostat is calling for cooling. Unfortunately, I can't read the labeling on the thermostat connections, so I can't tell if the wiring is correct or not. Did you change any of the wiring at the air handler (furnace)?
 
  #3  
Old 05-18-15, 03:50 PM
S
Member
Thread Starter
Join Date: May 2015
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thermostat wiring is as follows:
White - W
Yellow - Y
Green - G
Red - R
Blue - C

The only thing I changed on the furnace side was adding the blue wire to C. The blue wire was previously not used on either end.
 
  #4  
Old 05-18-15, 04:30 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,654
Received 90 Upvotes on 79 Posts
Do you have a voltmeter? If so, what voltage do you read between Y and C when the thermostat is calling for cooling? Nominally, you should be reading ~24VAC between Y & C.
 
  #5  
Old 05-18-15, 04:50 PM
S
Member
Thread Starter
Join Date: May 2015
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
I don't have a voltmeter (at least, not that I can find). I can hear the t-stat click when it is supposed to turn on...
 
  #6  
Old 05-18-15, 04:55 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,654
Received 90 Upvotes on 79 Posts
Turn off the power to the furnace and remove the thermostat. Jumper the R, G, and Y wires together. Turn the power back on and see if the outside unit runs. If it does, it indicates that the thermostat is defective. There are separate relays in the thermostat to control the blower, heat, and cooling. While you're hearing a relay click, it's possible that only the blower relay (R to G) is closing.
 
  #7  
Old 05-18-15, 05:11 PM
S
Member
Thread Starter
Join Date: May 2015
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
With those 3 wires together, the AC Came on... Looks like I am in the market for a new thermostat! Thank you very much for your help, it is much appreciated!
 
 

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