Common ac system leak point ?

Ok , I've dyed the system twice and still cannot find the stupid ac leak . It takes about 3 months for the system to go down and around here it's needed for the defrost , not to mention working in 100* heat at times - would be nice for a cooler ride home . Is there any common point or known place these trucks leak freon ?

Sarge

 

Could be any number of places. I've found on some Asian models that it's not uncommon for refrigerant to leak from the high/low pressure switches. If you are not seeing it after 2 dyes, this may not be it. Could be up the evaporator area - up inside the vehicle under the dash.

Filter thru this FSM material for the A/C section:

http://www.customtacos.com/tech.old/files/05FSM/repair.html

 

Check the shrader valves themselves. Put some soapy water around the caps and look for bubbles.

 

My AC has been leaking for years and this spring finally started leaking fast enough that I figured out it's my low side fill valve. I'd checked the valve in the past but it was such a slow leak it wasn't easily detectable until it got worse.

 

You may have to wait until the leak gets bigger. Just keep adding refrigerant every other month until it reveals itself with a faster leak. If the evaporator is leaking you would not be able to see that.

 

You can see the evap leak if you look in the right place. Run the dye through the system, pull the truck into a dark area (garage, etc) and shine the UV light down the firewall on the passenger side to where the condensate drain pipe is. If that is glowing green, you now know where the leak is. In a very bad place, too.

Common places to look, however.

(1) condenser. First thing road crap will hit. A rock or worse can nick the thing, it is under very high pressure, and it can crack in an instant.

(2) compressor seal which would usually show up as green (assuming dye + UV light) visible around the A/C clutch, or anywhere it can sling off of that pulley.

(3) the service ports are a royal pain in the ass. You can buy 'em at auto zone. You can even buy a tool that lets you replace them without having to bleed the system first. I usually test with a drop of PAG oil dribbled into the thing. NO bubbles allowed. Don't expect to hear it leaking. Most of the time it doesn't leak that fast. Maybe faster with engine running, but then you can't hear a woodpecker pounding on the hood.

(4) there are o-rings everywhere. Connections to condenser, to the compressor, to the receiver/dryer, to the evap at the firewall, and even hoses can crack as well.

(5) the pressure switches can start to leak.

Dye + UV light is your friend here, but you need a dark area and some time to inspect every hose and connection carefully. And as I said, don't forget to check the condensate drain as that is the only reasonable way to discover an evap core leak. Unless you want to go to the hassle of removing the evap core and visually inspect or pressurize it and hold under water.

These things are going to leak a little no matter what. 6-7 years is reasonable with no service. At that point, adding freon is probably a good idea. I've always reclaimed my freon after 7-8 years, pull a long hard vacuum to make sure there is no moisture, and then recharge. That usually restores normal cold air if it has begun to show signs of losing a little cooling ability. Note that I would NOT just hook up a can of freon and dump it in. Too much is just as bad (if not worse) than too little. Compressors do not like liquid on the low side. Too much freon and the low side pressure rises which causes the freon (R134 actually) to absorb significantly less heat since the pressure is higher than optimal which raises the freon boiling point. And you CAN lock up the compressor completely. Had a family member (distant family) completely wreck a compressor. This was in either a honda or toyota car, and the charge was only supposed to be 19oz total. He dumped a can in, probably grossly over-charged now, and when it was not cool enough, he added another. First warning as he was adding second can was serpentine belt squealing. Followed by compressor locking up. I helped him reclaim freon, evacuate, and re-charge but compressor was gone. Those little flapper valves do not like liquid being crammed through them in the wrong direction.

 

bought my truck new and it was leaking from the connection/oring on the condenser.

 

I've looked quite a few times with the UV light at night , both inside and out - from top and underneath as well , no luck . I'll definitely check the Schrader valves , forgot about those .
I recharged it twice now with the simple add-a-can freon from the parts store , paying very close attention to pressure rise and giving it plenty of time to circulate when filling on the gauge . My son in law has been to school and has the gauge sets , ect so I planned having him try it this weekend . Got a feeling it needs vacuumed down and filled properly , again . No way I'm going to the local stealerships , they can't change a light bulb without f-ing something up .

Appreciate the help

Sarge

 

Btw - it seems to take about 3 months to leak down , faster in the winter as expected . I keep thinking o-rings , but who knows ...
Starting to slowly hate this truck , rarely drive it and really prefer the old Land Cruiser .

Sarge

 

i just changed a evap core on a guys tacoma, used my borescope to find this one, went through the blower motor into the case. saw a mist floating by in the scope. pulled it out and this guy had leaves and crap packed in the bottom, it was a big job.

 

Going to try another recharge again today - and see if I can find a leak tonight in the dark , again ....grrr .
Sarge

 

On my 2012 the high pressure line coming out of the compressor was leaking around the crimp on the rubber hose. I noticed it because it had compressor oil on the rubber and dirt was sticking to it.

 

probably leaking right at the fill and test ports
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my 4runner does this, every 2 years I need to top it off

mine bubbles one 1mm bubble every 4 minutes
the plastic screw caps hold most if it in check, but it lets some leak out
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the main low pressure fill can develop leaks at the schrader valve

unscrew a/c system valve caps put soapy water look for bubblin

 

I already checked the Schrader valves once , might try it again . My son in law works at a semi shop so I may have him vacuum it down and do a proper ac fill up just so I can start from scratch . I just a clear time to get it done , no work lately but too many other things going on , and for once this year I'm making it a solid point to do some damned fishing .
Sarge

 

Be certain the valve caps have an o-ring in them to seal tightly-it's easy for it to fall out or fail. If it's good and in place, it should stop the leak. I've never had a valve that didn't leak a little and you can tell if the ring is in place.. when you remove the cap it'll 'pop' very slightly as the pressure is released in the cap.
May have to get new ones as the plastic may have small cracks in it, so b/s new ones have the o-ring.
I haven't found metal caps anywhere but Plastic ones should hold.
Good Luck

 

Good point - I forgot those caps have an o-ring , will check them out today .
Sarge

 

if you have a leak, your die will show. if you can't find it,, you may have bigger issues of it being in the dash..

 

Yeah, that's what I'm worried about . Dumped another recharge can in it the other day and got it working again . I sure miss the quality of the old R12 systems , worked on some 70's cars lately that still hold their charge and work fine despite closing in on 300k and a lot of system age . So disgusted with modern vehicles , disposable sure fits .

I did find the low pressure Schrader valve was a bit loose so gave it a snug just for fun but no sign of the dye .

Sarge

 

it's been over a year but did you ever find where the leak was? I'm in the middle of a near identical case

 

I'm leaking pretty significantly near the front on the drivers side of the grill. I started to add "freon" and it was a big enough leak that i could hear and see it coming out, but when I look I can't see where it coming from, I think in't an evaporator, it looks like an aluminum bottle, any ideas?