Inside fan blower only works as on heat mode, but not on a/c mode

Reply

  #1  
Old 09-09-20, 02:29 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Can not turn on the A/C fan blower when set to A/C mode(Auto & On) on control

If I switched to the Heat mode on thermostat control, the fan blower to blow air inside the house works normally on FAN “Auto” and “On” selections.

When I switched to A/C mode, the fan blower NOT working on FAN “Auto” and “On” selections, but the compressor fan running outside normally, and larger pipe was cold, and everything seems working fine outside the house, and I checked the furnace control board status light shown "RED" (Normal).

Any help is greatly appreciated.

 

Last edited by PETER LEUNG; 09-09-20 at 03:11 PM. Reason: WANT TO CHANGE THE TITLE
  #2  
Old 09-09-20, 02:55 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,608
Received 27 Votes on 22 Posts
Usually, the blower runs at different speeds for heat and cooling. It's possible that the winding for the speed that the A/C uses is burned out. A make/model would be helpful.
 
  #3  
Old 09-09-20, 07:24 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Thanks for your quick reply, would you tell me where to find the make/model.
 
  #4  
Old 09-10-20, 08:30 AM
Join Date: Jan 2009
Location: United States
Posts: 749
Received 32 Votes on 31 Posts
The motor would itself (in the indoor unit AKA air handler) would have a sticker with all of the vital information needed for wiring & make, Model RPM an other specs. Hopefully it is not an ECM motor but a regular & cheaper PSC one.
 
  #5  
Old 09-10-20, 02:05 PM
C
Member
Join Date: Aug 2008
Location: Texas, California
Posts: 1,498
Received 1 Vote on 1 Post
May be something simple, open the thermostat cover, and jump R to G, see if that starts the blower fan.
 
  #6  
Old 09-10-20, 04:44 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Can not turn on the fan on A/C

I could not find the sticker, but I found the wiring diagram without the model name on it (see attachments)



Also I checked the Capacitor attached to Control Board , I do not see any visual damage(see below):


 
  #7  
Old 09-10-20, 04:55 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
I jump R to G, sorry, still can not start up the blower fan.
 
  #8  
Old 09-10-20, 05:04 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,608
Received 27 Votes on 22 Posts
Unfortunately, the picture of the wiring diagram is too low resolution to read. Can you take another picture of the wiring diagram that includes only the wiring diagram portion of the label and is at a higher resolution?
 
  #9  
Old 09-10-20, 10:18 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,896
Received 1,343 Votes on 1,241 Posts
The model number can be found on the side wall near the burner.... behind the burner access cover.
I can see by the wire nuts in the blower wiring that the blower motor has been previously replaced.
 
  #10  
Old 09-12-20, 10:13 AM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Hi, Colcert,
I connected RC to G on thermostat, but still could not start up the fan, does the RC point different with the R ?
 

Last edited by PETER LEUNG; 09-12-20 at 10:51 AM.
  #11  
Old 09-12-20, 10:30 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,896
Received 1,343 Votes on 1,241 Posts
Usually there is a jumper between R and Rc. Some thermostats do it internally.
Do you have a wire on R and a different wire on Rc ?
 
  #12  
Old 09-12-20, 03:40 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Hi PJamax, there is no R on my thermostat. Just RC.
 
  #13  
Old 09-14-20, 03:25 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Hi PJamax, it have a wire on RC and a separated wire on the G. But there is no R port
 
  #14  
Old 09-14-20, 08:19 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Hi, guys,
I'll be out of town(working) for another week, so I could not take the closer shot of the wiring diagram and check the model number of my A/C at this moment. I'll do it right after I get back home sometime next week. Thanks.

 
  #15  
Old 09-22-20, 05:05 PM
P
Member
Thread Starter
Join Date: Sep 2020
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
Hi Guys,
I back home yesterday. After I done the online research for several days when I was out of town, then found the cause of the problem was the bad capacitor for startup the fan, so I replaced the bad capacitor yesterday , now the A/C fan back to normal. I hope I posted this resolution that can help a lot of people in the near future.

Thanks to all of you spending so much time and efforts to help me to resolve the problem.

HAVE A WONDERFUL DAYS TO ALL OF YOU.

 
  #16  
Old 09-22-20, 05:27 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,896
Received 1,343 Votes on 1,241 Posts
Good job. Thanks for letting us know how you made out.
 
 

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