Mike

A/C leak detectives give me advice

11 posts in this topic

@Ashley P @Disney

 

My wife started complaining of a hissing from the rear of her 2013 Tahoe a couple weeks ago.  I heard it tuesday coming from the rear a/c area.  Today the a/c pretty much wasn't doing anything.  Gauges read <30 low side and ~150 high side for the short amount of time the compressor is on.  You can hear that hiss in the rear when it's on too, but a little google says that may be typical of the expansion valve when the charge is low.

So I started looking for obvious leaks.  Nothing under the hood was wet.  The lines running to the back appear ok.  Nothing is dripping from the rear a/c weep hole, so I assume it's probably fine.  I looked at the condensor and saw a wet spot.

IMG_2288.JPG

 

To double check I figured I would throw a can of R134a with die in it.  But I decided to put the UV light on it before that and I saw this on the same spot.  Is this the typical amount of green you would expect from a slow leak?  Or could this be something else.  Now, at this point I haven't put die in it, so this is from GM or remnants of die from a previous repair.

IMG_2289.JPG

Would you call that a bullseye and put a condensor in it or keep looking?

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The "wet spot" on the condenser is an oily spot, right?  If there are no external sources I'd say that's ONE leak.  Might as well start there.

I'm hesitant on making a call on the "greenness" of the dye.   I'd lean toward saying that's probably indicative of a slow leak, but I don't want to put faith in your photo and my monitor.  But, if that color is only where the wetness is, surely it's dye.

I'd vote to make sure you've shined a light on as much of the system as practical to verify no other obvious problems.  Then it's condenser time.

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Yes, same oily spot is green.  I pulled the bumper for a better look and it’s more noticeable under uv.  Ichecked everywhere under the hood and nothing else.  I’ll see what else can be seen on the rear lines.  I don’t have a sniffer to check the evaporators, would oil make it into visible portions of the vents?

4070D4AC-F114-4020-8520-D613FECC8294.jpeg

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I think it would have to be a terrible leak to make it to the condensate drain.   A leak like dumping can through it in a day.  Maybe.   For the last 10 years my coworker does 95% of all AC work, but I don't think he's into the rear evaps (on GMs) as much as condensers.  

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I woke up at 5:00 at usual, so I figured I might as well get to work.  I double checked every visible a/c component and found nothing else.  I put the condenser on it and the vacuum pump is running right now.  We are going somewhere for a few hours today, so I'm going to let it sit with vacuum on it while we are gone.  If it stays bottomed out, I'll assume the evaporators are good and charge it.  It only holds 2.5lbs of r134a which I found for $5 per can (4 cans).  So worst case I'll be out $20 for refrigerant.

 

41811598_240229146837562_5842060832946520064_n.jpg

mstrpth and JohnC like this

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So far so good.  I charged it Saturday afternoon.  It blows 48* out the vents and was fine yesterday also.  The hiss is gone in the rear, so that must have been the expansion valve.

66sprint6 and Ashley P like this

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You know what's better than fixing the truck?  It's having a wife that noticed the hissing and didn't ignore it.  Many drivers run stuff into the ground before having it towed.

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11 minutes ago, Ashley P said:

You know what's better than fixing the truck?  It's having a wife that noticed the hissing and didn't ignore it.  Many drivers run stuff into the ground before having it towed.

Yes, she is almost too good at noticing small things like that.  

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