Burning Smell - the AC quit working.


  #1  
Old 05-18-15, 08:29 PM
P
Member
Thread Starter
Join Date: Dec 2014
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Burning Smell - the AC quit working.

Hello -

I have a Lennox model 80UHG4-75A-1 and on the weekend, the AC had been working, then we starting smelling a slight electrical type burning smell and then the AC went out.

Went to the attic and pulled the cover to see if I could see any damage or what was happening and everything looked fine. Lights on the board were blinking normal and no smell or anything abnormal, so I had the wife turn on the Thermostat again and everything worked fine for about 3 minutes and then the blower motor stopped working. No smell of anything burning next too the unit, but again had the slight smell of electrical burning down stairs?

Did some research and found out it could be either the capacitor and/or the blower motor. I do have a Multimeter, but too be honest, don't know how to use it to check to see if the capacitor or motor or both are bad.

I have unhooked and pulled the squirrel cage and have taken out both the motor and capacitor think that I would replace both, but neither one looks like it has any problems or smell to them.

Dose the symptoms sound like it would be one of these going bad? Any advice at this point would be greatly appreciated.

Thanks!
 
  #2  
Old 05-18-15, 08:43 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,639
Received 3,897 Upvotes on 3,494 Posts
Usually if it's the capacitor the fan won't start. If the fan runs for a few minutes and then stops it sounds like the motor needs to be replaced. Get the new cap. for it that is listed for it.
 
  #3  
Old 05-18-15, 08:49 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
Does the outdoor unit run?
I would measure for 24volts between R and C to prove the transformer is okay.
I would then measure between C and G for a fan signal.
(Although most boards should give you a low voltage error code if you lost low voltage)


Was the motor hot?
If the cap fails or the motor bearings fail the motor can get hot.



Do you get 120 volts to the motor with a cooling demand?
I'd measure from the terminal labeled Cool to the white neutral terminal.

If the motor is getting power and it does not run you can turn off power, unplug the motor leads andcheck the motor windings with an Ohm meter...




and check the capacitor with a meter that measures capacitance or just replace the cap.
 
  #4  
Old 05-19-15, 08:53 PM
P
Member
Thread Starter
Join Date: Dec 2014
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Hello Houston204 & PJmax.

Sorry for the late reply....just had Center Point out checking a gas leak at the meter.

I really need to learn how to use my multimeter and the diagram above will be a big help starting out....thanks, I will give this a try.

I didn't check the motor right away when it shut off the last time, so when I pulled the Squire cage, the fan was already cool....but the sticker on the side of the motor is faded so bad that I can't read the parts numbers etc. Don't know if this is because the unit is 15 years old or if the motor got hot and faded the label?

Since the better half is upset with the AC not working, I believe that I will be ordering a:
1. Motor - 60L2201 - Lennox OEM replacement 1/2 HP Fan Motor 115 VOLT 1PH and a
2. Capacitor - 22W7901 7.5 MFD 370 VAC

I want to thank you guys again for the advice and willingness to help out in the time of need.

PB
 
  #5  
Old 05-19-15, 09:05 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
I hope the motor was getting power from the board.

I have had to replace Lennox boards for this problem.
 
 

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