Ac issue - no cold air but thermostat , drip pan and blower all functional

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  #1  
Old 05-19-19, 08:55 PM
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Ac issue - no cold air but thermostat , drip pan and blower all functional

Hello

second time first time of season (late spring) upon trying to turn on ac - turns on (thermostat clock heard), no issue with drip pan/condensate, blower turns on - but no cold air

last year called tech to home and $400 later stayed - tour high pressure wire in blower was loose/disconnected. He reconnected it and instant fix.

now seems to be same potential issue (as noted above)

1) how do I check/confirm if the high pressure wire is disconnected ?
2) And if it is - why does this issue reoccur? Thanks.

Ps - I opened blower but I canít seem to identify the high pressure wire to assess if it is again disconnected.
Pss the blower is a Lennox.

Thanks !!
 
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  #2  
Old 05-19-19, 09:09 PM
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Welcome to the forums.

Hard to diagnose a problem with no system information.
Is this a typical split system with a gas furnace inside with an A/C coil and an outside condenser ?
I'm not aware of any high pressure wiring inside an air handler.

You said the blower inside works but the outside condenser does not.
Do you have VOM type meter and know how to use it ?
 
  #3  
Old 05-20-19, 06:31 AM
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My apologies... I wrote that while sweating (90 degrees) late last night - after trying to troubleshoot it for awhile

More info:
it is a typical split system, gas furnace inside, a/c coil and an outside condenser (lennox).

The thermostat clicks on
the blower turns on (inside unit)
the condenser (outside unit) turns on (fan spins normally)
but no cold air.

last year, this happened upon trying to use the a/c in the spring/summer - and the technician stated that in the outside condenser the 'high pressure' wire was loose/disconnected. (it was not the wire in the blower as I previously stated).

Does that make more sense?
 
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Old 05-20-19, 10:16 AM
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If the condenser fan is turning on then your problem is out in the condenser. It sounds like the compressor is not running. That may be as simple as a defective capacitor or a broken power wire to the compressor.

Wires rarely break by themselves but it does happen.
If the same wire broke again.... you need to find a new tech.
 
  #5  
Old 05-20-19, 11:06 AM
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Thanks Pete. I will check the capacitor but given it appears (visually) fine (no bulge/nl wires, no burns, etc) I would guess that the compressor wire is the issue (i.e. disconnected somehow? or broke?). This was my frustration with the almost $400 charge last year - no 'reason' for the wire to become disconnected - so 'simple solution' but likely deeper problem without caring that it would likely reoccur without truly knowing the diagnosis of cause.

I can test compressor wire with meter - how much voltage should it have? Hm... I will look it up as well.

Thanks again.
 
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Old 05-20-19, 12:32 PM
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Remove the wiring access cover, take a few pics and post them for us. The wiring you are looking at will be the contactor and the capacitor. How-to-insert-pictures.

If it was a defective cap..... the condenser would start up... the fan would run and the compressor would hum. After 10 seconds or so the fan would still run and the compressor would be shut down on overheat. It could remain hot for well over an hour until it internally resets. Then it will hum for 10 seconds and shutdown for another hour. This type of cycling is not good for the compressor.
 
  #7  
Old 05-20-19, 04:37 PM
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Both capacitor and compressor apparently replaced in 3/2016
Photo attached

compressor turns on and 'stays on' but still seems no cold air from vents in home - just 'slightly cool'

I also changed the air filter just in case as well.
 
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Last edited by Diyguysaysfly; 05-20-19 at 05:27 PM.
  #8  
Old 05-20-19, 05:49 PM
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If the units physically running but not cooling well, it could have a leak and is low on refrigerant.
 
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Old 05-20-19, 06:08 PM
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But if there is air coming from the vents but no cold air - could it be that there is truly 'zero' refrigerant? And wouldn't I see a leak outside? No leak anywhere. No hissing, no bubbling, no frozen line.
 

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  #10  
Old 05-20-19, 06:49 PM
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You would likely not see a leak unless you went hunting for it.
The amount of refrigerant in the system has no bearing on the amount of air coming out of vents, besides low charge causing a freeze up of the evaporator.
Refrigerant isn’t consumed as the system runs. It’s a sealed system.
 
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Old 05-20-19, 06:49 PM
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no ice, no hissing, no bubbling
 
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Old 05-20-19, 06:53 PM
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but wouldn't I see 'icing'/frozen line if I kept it on and the refrigerant was 'low'? and cold copper line is about 50 degrees or so. The line itself is 'sweating'
 
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Old 05-20-19, 07:00 PM
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One more thing... the air coming out of the fan (from above the compressor) seemingly was sometimes 'warm'/hot and then sometimes cool, i.e. seems to be varying temps. Could that suggest the capacitor is weak or faulty?
As an aside the capacitor appears normal and was replaced 3/2016 (just over 3yrs ago).
 
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Old 05-20-19, 07:01 PM
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That insulated line in the picture is near 50 degrees ?
If yes..... you should be getting cold air from the system.
 
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Old 05-20-19, 07:07 PM
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By the touch yes... surely it is not frozen and the outdoor temp is now in the 70s - the line feels about 50-60 degrees.
 
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Old 05-20-19, 07:30 PM
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What would be frozen would be the evaporator coil inside the air handler. Usually there will be no cold air and a very reduced airflow if that coil was iced over.

Can you see any condensate coming out of the air handler ?
If the coil is suspected to be iced over...... turn the A/C off and just let the blower run for several hours.
 
  #17  
Old 05-21-19, 06:39 AM
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air handler evaporator coil is not frozen
 
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Old 05-21-19, 09:18 AM
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Ok. Check the large refrigerant line at the air handler. Is it just as cold there ?
More than likely not which would mean the charge is low.
 
  #19  
Old 05-21-19, 04:24 PM
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Correction. A small area of the evaporator coil in the air handler is frozen. Turned off a/c and will run blower for a few hours. This will fix it?
I think I had done this intuitively yesterday before I read to evaluate the evaporator coil.
 
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  #20  
Old 05-21-19, 05:06 PM
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No, it will not fix it.
The frost/freezing isn’t the problem. It’s the result.
The problem is what’s causing the frosting.
 
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Old 05-21-19, 05:08 PM
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So now what? Hm. The ‘ice’ has now melted.

I did change the filter as it was quite dirty/clogged.

So I guess I have to hope that’s the cause.

Otherwise, I presume it is ‘low refrigerant’?

Can I fix that myself?
 
  #22  
Old 05-21-19, 05:17 PM
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No, you’ll have to call a technician for refrigerant issues.
Dirty filters can cause low airflow, which causes freeze problems.
 
  #23  
Old 05-21-19, 05:22 PM
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Gotcha. So I’ve got to just hope that the airflow and air temp improve now that the evaporator coil is defrosted and dried (left blower on few hours ).

Or is my refrigerant now low regardless of letting it thaw out and putting in new air filter (also checked all vent outputs - no clogs).

Any idea of anticipated price for this? In New Jersey.

Thanks.
 
  #24  
Old 05-21-19, 05:28 PM
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If it’s low on charge it’ll freeze up again.
Leaks aren’t good. If your unit keeps freezing due to low charge the leak should be fixed quickly.
 
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  #25  
Old 05-22-19, 10:22 AM
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Is it possible that the air filter being dirty and slowing down the airflow, caused the evaporator coil to freeze? and then even though defrosting the evaporator coil and changing the air filter - now the refrigerant will need to be recharged? BUT... it does not automatically mean there is a leak, true?
 
  #26  
Old 05-22-19, 10:35 AM
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If the unit needs to be recharged, then yes there’s a leak.
The equipment doesn’t consume refrigerant as it runs. The refrigeration circuit is a closed, sealed loop.
 
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Old 05-22-19, 10:13 PM
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A small area of the evaporator coil in the air handler is frozen.
If it were just an airflow issue...... the coil would be iced up completely. That small area that froze is probably where the refrigerant enters the coil. There wan't enough to travel any further.
 
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Old 05-23-19, 10:32 AM
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Ahhh....... so that highly suggests there is insufficient refrigerant, correct? I was wondering why the entire coil was not completely frozen.

Any idea of price range for a recharge of refrigerant? And I presume the 'leak' is somewhere along that evaporator line?

Thanks again!
 

Last edited by Diyguysaysfly; 05-23-19 at 10:52 AM.
  #29  
Old 05-23-19, 11:14 AM
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The leak could be anywhere, and should be found before recharging.
If you pay for someone to do a gas and go, youíll be paying for them to do it again and again till itís found.
 
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  #30  
Old 05-24-19, 11:26 AM
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So... as expected hvac company came - checked pressure and it was very low. Rep stated that they do not normally do a dye test to 'find the leak' as the cost of that in time and labor and possibility of not even finding the leak is not worth it. He suggested to try at least once to just recharge the refrigerant. I have a 9lb system (plus likely 2 lbs in the lines) , i.e. 11 lbs total of refrigerant and when he added refrigerant it took 6.8lbs to fill it up.
But now my concern is that it could take days/weeks for it to again leak out or it could take months or so - depending upon how slow/fast the leak is.
Suggestions? Feedback?

The cost for 6.8lbs of refrigerant/labor was $500 - seemingly not 'too bad' given I anticipated it to be more. However, the risk is on what if it leaks out in the coming days to weeks - then it was throwing that $$ in the trash!

I plan to call Lennox as well - as the system is only 6yrs old - so there 'might' be an extended warranty, not sure.

The rep also suggested that leaks are usually there from the get go, i.e upon whomever installed it, did not do a good job.... as the air handler is in our attic - not a likely place to get damaged and the exterior condenser is well covered/protected from the elements (although still always some small risk to the coils being damaged there).

Ugh.
 
  #31  
Old 05-24-19, 11:51 AM
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There should be no leaks from startup.
I carry an electronic leak detector, actually 2 different ones. Most leaks I can track down in 1-2 hours.
Your $500 in refrigerant is leaking back out to the atmosphere as we speak. How quickly no one knows until the leak is found.
Unless your system was registered by you or the installer when new, itís no longer under warranty.
 
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Old 05-24-19, 11:51 AM
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Did they not even breakout a sniffer..... refrigerant detector ?
That was the very least they could do.

I'd be concerned too.
The only thing you may get from Lennox is a warranty still in effect on parts only.
Some are good for ten years if the unit was registered with them.
 
  #33  
Old 05-24-19, 12:48 PM
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no electronic leak detector or any kind of refrigerant detector (sniffer). Is that 'typical' to just state 'it is not worth trying to find it?' The guy was very nice but also very 'matter of fact' about it not being worth his time or my $ to 'search for the leak.'

Should I attempt the 'soap and water' test - and look for bubbles? If so, where would I be most likely to find a leak?

Or is it worth me purchasing an electronic leak detector - I see they range from $30 to $300.

I presume the best place to look first is nearest the evaporator coil and/or the condenser - as I presume those areas are the most common (especially the condenser unit area - given this is outside of the home - exposed to the elements)?

Not sure what a 'sniffer' refrigerant detector is though.
 
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Old 05-24-19, 01:30 PM
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A sniffer is a detector. A basic one would be useless. We carry semi-expensive/expensive ones that are more sensitive. You got a "gas n go" tech. Recharged and left.

We check at all the visible soldered connections and schrader valves first. To open up the evaporator and check inside is a chargeable job. The inside evaporator is where most leaks are found.
 
  #35  
Old 05-24-19, 02:09 PM
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With soap and water - I checked the soldered connections and the entire visible area of the evaporator coils (see photos). No obvious bubbling.

1) how do I check the schrader vavles?
I just watched a video of a guy who changed the schrader valve in the field while the system was on (not saying that is where my leak is - but just looked cool - and not sure how to check if that schrader valve near the condenser is the source of the leak.

https://www.youtube.com/watch?v=om3RLoKCjog (not my schrader valve but interesting)

2) how do I better check the evaporator coils - if that is where the most common leaks occur?

Thanks.
 
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  #36  
Old 05-24-19, 03:13 PM
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Okay. Checked both schradsr valves via soap spray. Nothing. No leak. Darn! Was hoping for that to be the source? Checked evaporator coil with soap spray. Nothing. No leak.

Hm, how do I effectively check the coils around the outside condenser/fan?

Hmmm
 
  #37  
Old 05-28-19, 04:31 PM
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Is the soap spray method effective to confirm the schrader valves are not the issue? Any how does one confirm the coils do not have microleaks? Thanks.
 
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Old 05-28-19, 04:46 PM
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The soap bubbles are effective for obvious or easy to access joints and fittings. Anything beyond will require an electronic leak detector.
 
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Old 05-28-19, 04:53 PM
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ah... so the coils would surely require an electronic leak detector. I've used the soap bubble test for the valves, joints and fittings and no apparent leaking at all. I presume it must be in the coils (inside air handler) or outside (condenser unit).

crud. thanks.
 
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Old 05-28-19, 05:07 PM
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Some leaks are very small and require very sensitive leak detectors and the knowledge of how to use them.
I’ve found leaks of just a few ounces per year with my DTech and H-10.
Some leaks require elevating system pressure with nitrogen.
 
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