Tracking down an A/C leak

[rasouth]

Hey guys! I am trying to track down an a/c leak. A couple months ago my a/c started blowing warm air so I went and got some R134a with UV dye and the system was blowing cold air once again. After running the engine for a while off and on through out the day until night fall, I put on my funky yellow glasses and switched on the UV light. First off I noticed I have a leaky valve cover gasket, but looking all around I could not see any glowing UV dye. I crawled all over the engine checking all the connections and hoses I could see. I crawled underneath trying for a good look at the accumulator but did not see anything glowing. Now my accumulator is original with the rubberized wrapping on it. I have read that these can rust out and cause pin holes but my question is how can you tell if there is a leak underneath the wrap? I tried scaping some of the wrap off and I get a slight glow from where I scraped but I think it is more of a reflection off the scrape marks. I was also able to look in the blower box behind glove box because I recently had to replace the blend door and did not see any glow from inside.
Would one of those leak detectors be more reliable than the UV dye?

 

[Pete Deering]

Hey guys! I am trying to track down an a/c leak. A couple months ago my a/c started blowing warm air so I went and got some R134a with UV dye and the system was blowing cold air once again. After running the engine for a while off and on through out the day until night fall, I put on my funky yellow glasses and switched on the UV light. First off I noticed I have a leaky valve cover gasket, but looking all around I could not see any glowing UV dye. I crawled all over the engine checking all the connections and hoses I could see. I crawled underneath trying for a good look at the accumulator but did not see anything glowing. Now my accumulator is original with the rubberized wrapping on it. I have read that these can rust out and cause pin holes but my question is how can you tell if there is a leak underneath the wrap? I tried scaping some of the wrap off and I get a slight glow from where I scraped but I think it is more of a reflection off the scrape marks. I was also able to look in the blower box behind glove box because I recently had to replace the blend door and did not see any glow from inside.
Would one of those leak detectors be more reliable than the UV dye?

View attachment 341987

View attachment 341988

The leak detector could be used to check the inside of the EVAP case. On my 95, my leak was on the inlet of my EVAP (Lower connection). The connection vibrate there causing a small leak. Also a common leak area are the service ports. Sometime the valve do not seal all the way. The UV dye show up there from the on and off connection. To check those, drop some AC oil in them to see if they bubble. I used both system to check for leaks. After a installation I sweep all the connections for leaks with the detector. Sometimes the quick connects, don't lock in all the way. In your case I uses the UV light. my problem is I uses alot of dye and it looks like a blood bath and cross contamination. Soap and water could also be uses.

 

[Pete Deering]

The leak detector could be used to check the inside of the EVAP case. On my 95, my leak was on the inlet of my EVAP (Lower connection). The connection vibrate there causing a small leak. Also a common leak area are the service ports. Sometime the valve do not seal all the way. The UV dye show up there from the on and off connection. To check those, drop some AC oil in them to see if they bubble. I used both system to check for leaks. After a installation I sweep all the connections for leaks. Sometimes the quick connects, don't lock in all the way. In your case I uses the UV light. my problem is I uses alot of dye and it looks like a blood bath and cross contamination. Soap and water could also be uses.

The only places, which are hard to find are; there are connection on the pass and driver side top by the radiator, or the condenser in front bottom rust out or something hit it. You probably did not check there, Along the bottom row.

 

[C420sailor]

The electronic leak detectors are pretty dope. You can narrow with them, then use soapy water. The dye should work too, though.

Evaporator could have pinholes. Can’t see that easily bc it’s enclosed in the box.

 

[Pete Deering]

You can stick the electronic leak detector into the lower vent or into the drain hole in the evaporator case to check for leaks

 

[rasouth]

I have checked the service port caps and except for a tiny glow from them nothing stands out. I have crawled under the engine looking up, down and all around at any connection I can see. I am now low on refrigerant as the clutch comes on and shuts off every few seconds. It's gotta be going somewhere. I put the UV dye in it a month ago. About the only places I can't see is the hose that goes behind engine along firewall and back side of the evaporator.

 

[crunchie_frog]

There is a drain line from the evaporator on the passenger side you can see under the vehicle. When the humidity in the air being cooled is condensed on the evaporator, there will be water dripping out the drain. If there is a leak in the evaporator, the dye will be diluted due to the water condensing on it so the UV dye coloring will not be nearly as strong. At least in my case, when I had a multiple small leaks in the evaporator, there was a slight UV dye color you could see from the drain line. Of course, I do not know if your leak is in the evaporator but it does happen and you cannot see the evaporator without taking the taking the evaporator housing apart.

 

[Pete Deering]

The electronic leak detectectetectordetededetec

I have checked the service port caps and except for a tiny glow from them nothing stands out. I have crawled under the engine looking up, down and all around at any connection I can see. I am now low on refrigerant as the clutch comes on and shuts off every few seconds. It's gotta be going somewhere. I put the UV dye in it a month ago. About the only places I can't see is the hose that goes behind engine along firewall and back side of the evaporator.

The UV dye will show up. I know the filter/dryer can and do rust out, but my was fine. I don't think the hose, that goes in back of the engine has a hole check the crimp connection at the ends. I know hoses leak. the thread end connection are very unlikey, On one car I have, I had the AC hoses wrap with heat tape, the UV dye did show up thru the wrap. I also brought two commercial brand leak detector liquid, they did not work. Home depot and Lowes sell the commercial product. Some leaks are hard to find. The service ports could be the leak. Keep filling the system and look for the leak. One thing to NOTE: when you loss freon , you loss AC oil. After 8 years going thru what are experience my compressor became noisey and fail. My clutch bearing also fail at the same time. There is a life span on these system. The manifold assembly is not very expensive, keep looking.

 

[rasouth]

I broke down and bought a leak detector last night. I have crawled underneath looking at the condenser, accumulator, hoses, etc, and I see nothing glowing. I have traced hoses, connections and fittings with no luck. Either the UV dye is not strong enough to see or I have no leak in my system, yet I am loosing oil somewhere. Any suggestions on using the leak detector? First I need to recharge system.

 

[Pete Deering]

I have checked the service port caps and except for a tiny glow from them nothing stands out. I have crawled under the engine looking up, down and all around at any connection I can see. I am now low on refrigerant as the clutch comes on and shuts off every few seconds. It's gotta be going somewhere. I put the UV dye in it a month ago. About the only places I can't see is the hose that goes behind engine along firewall and back side of the evaporator.

 

[Pete Deering]

Turn the detector on away from the vehicle. Set the indicator to the middle setting and sweep the wand below the hoses and fitting. The freon is heavy Than air, so it drops. It another tool.

 

[sport trac jr.]

Turn the detector on away from the vehicle. Set the indicator to the middle setting and sweep the wand below the hoses and fitting. The freon is heavy Than air, so it drops. It another tool.

You charged up and its running cold......how long does it take to leak down to warm......I had a truck I got that sat for 2 years
the AC was running warm....topped off and its held for 2 years.....I did not look for a 2 year slow leak.....So how long does it take to leak down...

 

[Pete Deering]

Your AC system is a pressurized system. the pressure in the increases as the
ambient temperature increases. And also if the system is running. For a example a normal system will operate with a high side pressure at 80 degree F around 200 psi and the low side between. 20 to 40 psi. These pressure will increase as the ambient temperature increase. Scan the system In the off condition. The low and pressure will be the same. Even if your system was in a vacuum it would not hold that vacuum; that's what your trying to find.

 

[rasouth]

This past year it takes less than two months for the air to go from cold to warm, so I think it's a big enough leak. Thanks for asking Sport Trac jr. I think I forgot to mention that in my original post.
I got the leak detector last night, charged up system this morning and blows cold air. Followed directions and set detector to setting 4 and slowly went over compressor, connections, hoses, as much of the condenser connections as I could over to the accumulator and got a hit. Could not pinpoint the exact place, maybe the big nut connection coming off the accumulator and then no more hits. Turned up settings to 6 and repeat and no hits. I kept retesting area at different settings, move to different area, walked away for a few seconds, retried connections with no luck.
Started engine back up and let run for a few and started testing. I got a hit at the line going into the evaporator. I sprayed soapy water on it and got a bubble. It seams to only leak when engine is running or just after I shut engine off. If I wait 10 minutes I get nothing.
It's kinda hard to see but I outlined the bubble. Now what? Is there a fitting that can be tightened or do I have to remove everything and evac the system and replace o-rings?

 

[rasouth]

UV dyes and a leak detector could not find the leak but good old fashion soapy water did the trick.

 

[Pete Deering]

UV dyes and a leak detector could not find the leak but good old fashion soapy water did the trick.

You need to replace the Evaporator, orifice tube, make sure you buy the right one. There are 3 coLor units, New accumulator.

 

[C420sailor]

If you’re gonna rip into the AC, consider giving it a really good once over. Replace all the seals and stuff that you can...if your compressor is very high time, consider a quality replacement.

You don’t want to fix the leak, charge it up, and then figure out a few months later that something else was leaking too, or is now leaking. Or, god forbid, have your compressor eat itself soon and **** up your newly installed components.

@donalds did a great thread on a full system overhaul he did, soup to nuts.

 

[rasouth]

Thanks for everyone's input. I might wait to fix it because it is hot here in SoCal right now. I will look into parts to see what I need.
Hey, Pete... any way to tell what color orifice tube I need before ordering parts?

 

[sport trac jr.]

Thanks for everyone's input. I might wait to fix it because it is hot here in SoCal right now. I will look into parts to see what I need.
Hey, Pete... any way to tell what color orifice tube I need before ordering parts?

How about change the front line seals and filter and do a pressure test it usually the seals and see if it holds before pulling...
its prob the core if not the seals...

 

[Pete Deering]

Thanks for everyone's input. I might wait to fix it because it is hot here in SoCal right now. I will look into parts to see what I need.
Hey, Pete... any way to tell what color orifice tube I need before ordering parts?

For me , it was in the service manual. You probably go on ford parts direct, put in your vin, AC section and it should list the correct one to uses. After that You can buy the parts from rock auto. Those three parts are inexpensive. I see you have a 96, on my 95 I used a red color orifice. Also you will not need a orifice extractor tool because you will replacing the evapator and installing a new orifice in the connection (inlet). I remove my wheel liner and everything on top to replace the evaporator.it's