a/c not turning on

Reply

  #1  
Old 06-30-18, 11:24 AM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
a/c not turning on

this is a rental unit and occupants trashed the place, I suspect the ac has been out for many months

nothing happens when i turn on the ac at the thermostat, no noise, nothing
doesn't trip the breaker or anything (i reset the breaker also)

not sure what steps to take first, i just gathered a bunch of pictures for now

the ac was purchased new at the end of 2010/ start of 2011

https://drive.google.com/open?id=1fH...3ID2vkaoGmRcWt
https://drive.google.com/open?id=1Xf...lG1z19OUVHhs3s
https://drive.google.com/open?id=1jA..._kAA5Z_08EbyQK
https://drive.google.com/open?id=1_E...QUQv4CuQJ8Pmb2
https://drive.google.com/open?id=1NA...wR23h99qATWjid
 
Sponsored Links
  #2  
Old 06-30-18, 11:44 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,260
Is the low voltage wire even connected to this unit?
 
  #3  
Old 06-30-18, 02:50 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
I don't even know what a low voltage wire is, I will probably just get a HVAC person to come and check it out.
 
  #4  
Old 06-30-18, 06:31 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,260
I believe it shown in AC4 JPEG.
 
  #5  
Old 06-30-18, 07:31 PM
Member
Join Date: Oct 2016
Posts: 698
I see an aftermarket high pressure cutout control that’s been bypassed, but the other pictures don’t show anything.
You’ll need some tools and a meter to troubleshoot. Do you have those things?
I don’t see a control wire going into the unit either.
 
  #6  
Old 06-30-18, 09:36 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,260


The yellow arrow is pointing to the most likely location of your control wire.

It usually looks more like this but your wire is in a plastic conduit...




It will usually connect to the condenser with a couple of orange wire nuts...


Turn off the thermostat before trying to reconnect the 2 wires or you might pop a fuse in the indoor unit. Usually 3 amp for gas furnaces and 5 amp for air handlers.

 
  #7  
Old 07-02-18, 10:22 AM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
Here is a pic of the run capacity and the control wire?

https://drive.google.com/file/d/15_9...w?usp=drivesdk
Name:  acbox.jpg
Views: 242
Size:  79.7 KB
 

Last edited by PJmax; 07-02-18 at 11:13 AM. Reason: added labeled pic from link
  #8  
Old 07-02-18, 11:16 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
The two connections I circled in red are the 24vac that activates the contactor. As mentioned.... I don't see any protection devices, like hi/lo pressure switches, connected.

I also only see one single capacitor. Is there a second one elsewhere on that unit ?
The connection I circled in white looks to be a connection that would normally be on a capacitor.

You may be in need of some "hands-on" professional help there.
 
  #9  
Old 07-02-18, 06:50 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,260
Looks like a dual cap on my ipad. Red is Com, Yellow is Hem and brown is fan.

I have seen some serious issues when the low voltage wire is run in the same whip as the high voltage wire.

Water got inside of the whip and shorted the high voltage with the low voltage.
I had to replace the contactor, the thermostat and the furnace control board.

I hope this is a very different issue.
 
  #10  
Old 07-03-18, 01:40 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
had the HVAC tech come and check it out. he got the unit running from inside the garage but could not get it working from the main thermostat.

the previous tenant was running something very illegal, there were new vents in the garage, and wiring that led to what most likely used to be an alternative thermostat

hvac tech seemed really honest and stated that the whole unit would need to be replaced because:

1. it was very old, likely from 1986 when the house was built, the flue (vent?) inside the garage needed to be replaced and they don't make them anymore. he said it would be dangerous to operate, in case there was a leak, the house would intake carbon monoxide (dioxide?)

2. the evaporator coil is corroded.

3. the condenser is almost 8 years old and uses R-22 refrigerant while may not be a problem now, won't be available to use in the near future.

he also stated that other a/c companies may offer to fix it, but he couldn't do it because he wouldn't be able to sleep at night.

it is mounted to the garage's ceiling, not a freestanding ac/heating system.

any thoughts? do i just trust this guy or get a 2nd opinion?

there was no charge for the service call, and he was out there for around an hour.
 
  #11  
Old 07-03-18, 03:56 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
Looks the furnace was from 1986 but the A/C was either replaced or installed at a later date if it was only 8 years old.

Condenser 8 years old and R-22 are not issues.
A corroded evaporator, and I guess leaking, is a problem.

Should you trust the guy...... probably but you should get a second estimate to replace existing equipment.
 
  #12  
Old 07-03-18, 04:24 PM
Member
Join Date: Oct 2016
Posts: 698
So what did he find was keeping the unit from running?
 
  #13  
Old 07-03-18, 04:34 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
I think it was just the thermostat not wired up to the house

But yeah, I will get another estimate. If they can fix it and it's safe, I will go that route.

I think he manually turned it on using the wiring from the thermostat that used to be in the garage
 
  #14  
Old 07-28-18, 07:36 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
So we had the AC working for 3 weeks and today all that happens is the blower runs non stop but the outside condenser doesn't run at all (no fan or any noise). cap looks fine, but i will test it.

it has been really hot in las vegas, over 110 the past few days. i am not at this house most of the time. maybe 3-4 hrs each day. i wasn't there all day yesterday.

we have been doing some construction and the air filters have lots of fine dust. what's worse is one of the air filters was dented pretty badly, and there was a nice big gap allowing unfiltered air in.

what i'm thinking is lots of dust and crap got into the evaporator coil and now it may have frozen because of the dirt blocking it..

question is, how do i check the evaporator coil?

it's ceiling mounted and there doesn't appear to be any panels from when looking at it from the front... similar to this but with a lot less going on:
http://www.goosebumpsac.com/wp-conte...dOnCeiling.jpg

i will take a photo tomorrow.
 
  #15  
Old 07-28-18, 07:43 PM
Member
Join Date: Oct 2016
Posts: 698
If the outdoor unit isn’t running then it’s not frozen.
You’ll need to start by checking control and high voltage in the outdoor unit.
 
  #16  
Old 07-28-18, 09:33 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
How do I check control and high voltage in the condenser?

Also there was a bunch of insulation around the condenser unit (trash, insulation for walls and ceilings) that blew over from a storm. It was kind of stuck in a corner where the condenser unit is... Could that have caused this problem?

I just remembered, on Wednesday, I had new carpet installed. During the installation, I noticed a very faint burning smell circulating throughout the house but thought it was something to do with the new carpet being put in, like one of the tools used... Maybe it was the compressor overheating?
 

Last edited by gecko316; 07-28-18 at 11:20 PM.
  #17  
Old 07-29-18, 09:33 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
Reread the thread..... we've told you where to check for power.

In post 7..... I've circled where the 24vac should be present.
The 240vAC will be measured at the bottom of the contactor in that same picture.
 
  #18  
Old 07-29-18, 10:33 AM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
https://drive.google.com/file/d/1DpZ...w?usp=drivesdk
Name:  contactor1.jpg
Views: 138
Size:  75.4 KB

https://drive.google.com/file/d/1tQ8...w?usp=drivesdk
Name:  contactor2.jpg
Views: 129
Size:  56.5 KB

Pics above are my multimeter and contactor. I think I have the multimeter at the right setting.... Here goes

I don't think I'm using the multimeter right or connecting it to the right parts of the contactor. Don't get any reading at all, even when I have the AC set to cool
 

Last edited by PJmax; 07-29-18 at 12:45 PM. Reason: added pics from links
  #19  
Old 07-29-18, 12:34 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
The meter setting at it's limit. That means the 200vac setting is good for 200v and down. That setting is fine for the 24vac. For 240vac you need to use the 500vac setting. If the voltage is unknown..... start at the highest setting and work down.

In the picture below.... I've labeled the 24vAC at the two wirenuts. Ultimately that 24vAC should be connected to the terminals on each side of the contactor. Yellow wire on left side and the other terminal is on the opposite side with a blue wire. The 240vAC needs to be measured at the bottom of the contactor where the main power wires connect.

Name:  acbox.jpg
Views: 134
Size:  64.6 KB
 
  #20  
Old 07-29-18, 12:44 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
So one multi meter probe on where the red wire goes to the contactor and the other probe on where the blue wire goes to the contactor for 24VAC?
 
  #21  
Old 07-29-18, 12:46 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
No. The 24vac wires are yellow and blue. They are the same wires that are in those wirenuts.
 
  #22  
Old 07-29-18, 12:55 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
yeah sorry that's what I meant, as per your picture on post#7
 
  #23  
Old 07-30-18, 08:50 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
got 240v but could not get 24v, nothing showed up

any ideas? do i need to go to the control board or something?
 
  #24  
Old 07-30-18, 09:34 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
I had to go back and reread the entire thread as I'm lost.

Ok. You have the 240v but not the 24v. You had a similar previous issue and it was with the thermostat.
The thermostat was replaced ?
I believe the blower IS running ok at this time.

That leaves..... bad thermostat. Not likely if replaced.
Possible condensate float issue from high condensate water level or wiring problem.

The thermostat cable goes from the condenser outside to the air handler. There should be splices at the air handler. You should be able to see the color of the two 24v wires used in the thermostat cable outside spliced at the air handler. Find those colors at the splice. Make sure they are connected.
 
  #25  
Old 07-30-18, 09:50 PM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
Thermostat was not replaced, it just wasn't wired to begin with

Previous tenant had it connected to another thermostat in the garage, then disconnected everything

That was the original problem, service guy charged me $120 to diagnose and fix it

Fast forward to today, I have no 24v at the contactor outside on the condenser.

Blower works, it runs non stop, even if thermostat is set to off, fan auto or on, doesn't matter.
 
  #26  
Old 07-30-18, 10:06 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
Is the air handler a gas furnace too ? If yes..... you more than likely have lost the 24v source.
 
  #27  
Old 07-31-18, 07:27 AM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
Yes, I think it's both gas furnace and air conditioning

HVAC tech is saying the (24v?) transformer is burning out because of a short circuit somewhere.
 

Last edited by gecko316; 07-31-18 at 09:21 AM.
  #28  
Old 07-31-18, 07:37 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
Ok.... furnace makes sense.

Many furnaces are designed so that on a loss of 24vac or one of the furnace safety switches opens...... the blower will run. This lets you know there is a problem.

I'm guessing the tech was back and possibly changed the transformer ?
It would be ideal to have a fuse holder and 3-4A fuse installed in one of the 24vac transformer lines to keep it from burning up in the future.

It can be difficult to find a wiring/short problem. A typical problem location is between the house and the outside condenser as it's exposed to the weather, external damage (weed wacker) and animals.
 
  #29  
Old 08-11-18, 10:52 AM
Member
Thread Starter
Join Date: Aug 2016
Posts: 60
PJmax, you are right on the money

tech put a new transformer in, and blew that one too.. then added a fuse like you said and another transformer (and possibly found the short and fixed it?). he was at it for about 3 hrs.

got charged $220, and it's been working good for the past 10 days, really need it in this extreme las vegas heat.
 
  #30  
Old 08-11-18, 06:59 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 45,144
Glad you got the problem fixed.
At least if the short has not been completely cured.... you won't lose the transformer.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes