Condensor Fan Running / Compressor Not - Take Two

Reply

  #1  
Old 08-07-19, 06:10 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
Condensor Fan Running / Compressor Not - Take Two

Lennox 14 SEER A/C (6 years old)
ThermoPride Oil Furnace (25 years old)

A/C set to 76 during day, 72 during evening.. uses adaptive recovery.

3 weeks ago, just after we got out of a heat wave (Upper 90s), I went back to work. That Monday, it was not quite as hot, but mid 90s. The A/C was at 76 during day.. then started dropping. Bad storms came... and my wife noticed a surge through the TV. Around this point, it stopped dropping temperature, but both fans were running.

Assuming it was a power surge, after checking some things (voltages, capacitors, etc), I left the unit off for about 2 hours and powered things back on. Things are great again. Delta-T around 20 degrees.... everything seemed OK... for 4 hours. 4 hours later, the thermostat started going haywire.. I found the 25 year old furnace fan center/transformer smoking. I replaced this and even had an HVAC guy come check things out.. although he really didn't do that much. All was fine. for 3 weeks.

Fast forward to today. Virtual repeat. Mid 90s, storms in the afternoon and I'm at work. A/C dropped to 74 from 76... then stopped cooling, both fans running. The outdoor capacitor tested out 44/5 (45/5), but I had a spare one.. and read online that a bad dual cap --could-- cause overheating.. and it looked rusted on top, so I replaced it. The fan center is not smoking and the thermostat seems OK.

Do I keep getting power surges and this is the cause? With the good Delta-T I seem to be fine on refrigerant. Is this a TXV problem --- not 100% sure if I have a TXV, as we moved in last year (unit was fine all summer).


 
  #2  
Old 08-07-19, 06:49 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,725
Received 1,316 Votes on 1,216 Posts
So even after waiting for a while with the unit off...... the compressor still isn't running ?
It should restart when it cools off.
You said the fan was running and the compressor wasn't. That may have been when you checked it. You may have a problem with the condenser fan stopping or slowing down causing an overheat issue.

It is not a problem with the proportioning valve.
 
  #3  
Old 08-07-19, 06:56 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
On the first occurrence.. everything was fine after 1-2 hours of turning everything off. All was well.

This time, I haven't tried again yet... Was just going to try it in the morning.

UPDATE: After leaving everything off for 2 hours, all is working well again.
 
  #4  
Old 08-07-19, 10:02 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
Is your power blinking?
What thermostat are you using?
Does the stat use batteries? Is it a digital thermostat?

Short cycling can cause similar symptoms.
A digital thermostat with a 5 minute time delay (that uses a common wire and does not use batteries) can help if this is the case.
 
  #5  
Old 08-07-19, 10:13 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
I was not home during either of the two instances... though, I'm told the power did blink during the first -- this is when my wife was home. Thermostat is a Prestige IAQ.
 
  #6  
Old 08-07-19, 10:21 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
I love that thermostat.
I configure the time delay on that thermostat for 0 to 2 minutes with chill water applications, or 5 minutes for standard residential applications. ( I almost never install that thermostat on anything but high rise chill water units).

Do you know how to check your time delay setting?
(An easy method is to turn the stat On, then Off then back to a cooling demand and then time it to see if you have a 5 minute time delay.
 
  #7  
Old 08-07-19, 10:27 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
Is this in the "Installer Options".... "Minimum Compressor Off Time"???

Is set to 1 minute (says Default is 5)
 
  #8  
Old 08-08-19, 12:57 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,725
Received 1,316 Votes on 1,216 Posts
One minute is too short. It should be left at the 5 minute default.
 
  #9  
Old 08-08-19, 07:08 AM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
I've made that change to the thermostat.

I had someone tell me that it may be the contactor. Does that sound possible? The one on the unit is a hcc-1xq01ab106. I do not see any burnt connectors or wires in the area.

It is tough to see inside the outer unit, but I cleaned the coils in the spring and they look very clean. Will probably open her up this weekend to double check.

Just to throw a wrinkle into things.. a previous resident has one of those "cut your compressor off" devices on hot days from the power company wired into the outdoor unit. I opted out last year and the power company tells me that the 1 time they did it in 2019 does not match a day where I had issues but I am having them remove it.
 
  #10  
Old 08-08-19, 01:13 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
We're running so far so good today. 89 degrees outside and sunny.

Today, cleaned the condensor coils... they were not terrible.. just a small amount of dirt, etc.

Still a bit clueless.
 
  #11  
Old 08-10-19, 12:08 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
Still running swimmingly but temps have been just short of 90... I saw my issues on mid-90 degree days and strangely when storms started to pop up in the area. Had some upper-90 days just prior and had no issues... FYI - Our design temps are right around 90.

- Did I just get unlucky w/ two surges that affected nothing else (that I noticed)?
- Was my run capacitor just slightly weak enough to cause compressor overload? Only on hot days though? FYI - I believe it was ~6 years old.
- Can slightly dirty condenser coils be enough to give me grief?
- Did the 1 minute compressor off delay combined with the adaptive recovery cause some kind of strange short cycling when it brought down to setpoint?

I really don't know where to go at this point, other than to pray..
 
  #12  
Old 08-17-19, 12:19 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
This one is finally resolved -- most likely. Power delivery issue.

Turns out, there's a recurring electrical issue in a nearby neighborhood that intermittently causes an undervoltage.
 
  #13  
Old 08-17-19, 01:00 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,725
Received 1,316 Votes on 1,216 Posts
With an aging infrastructure..... finding more and more power delivery issues is common.
 
  #14  
Old 08-20-19, 08:45 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
Good grief... so my furnace fan transformer went again.. about a week after the last surge... and a month after the last transformer.

This has to be related.. right? Did the under voltage occurrences damage this transformer as well?? I'm at a loss...
 
  #15  
Old 08-22-19, 05:44 PM
M
Member
Thread Starter
Join Date: Feb 2018
Location: US
Posts: 16
Received 0 Votes on 0 Posts
Had to call in a pro... was at the end of my rope.

Checked everywhere for shorts... none found.

He took out the 40 VA transformer and wired in a 75VA transformer w/ a manual reset in case it occurred again.

After he left, I changed out the contactor as it seemed like the last logical thing to do.

Hopefully this story is over.
 
 

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