A/C leak Dye question
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,237
Likes: 117
From: San Antonio Texas
A/C leak Dye question
Well, my A/C finally crapped out the other day. I've been suspecting it was low on 134 by the way it started cycling. I put wires for a small light across the AC clutch plug and taped the little bulb to the windshield so I could see when the clutch cycled. Sure 'nuff the thing was on constantly at idle, but would cycle after I got the rpm up over 2000. When it would cycle OFF it would only do it for about 5 seconds and then click right back on again and run for about 20 or 30 seconds. Couple of days later it was dead!
Question for you AC "X-spurts". I want to put some dye in there with enough 134 to make it run and see if I can find a leak, but I don't know how much dye to put in and I don't know if I need to add more oil. When the 134 leaks out enough to cause the low pressure switch to cut everything off, does the lube oil usually go out with it, or mostly stay behind?
Question for you AC "X-spurts". I want to put some dye in there with enough 134 to make it run and see if I can find a leak, but I don't know how much dye to put in and I don't know if I need to add more oil. When the 134 leaks out enough to cause the low pressure switch to cut everything off, does the lube oil usually go out with it, or mostly stay behind?
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 277
From: Melbourne, Victoria, Australia
Hi just use a dish washing soap and water in a hand spray bottle, and spray that over any joins. 
The most common areas for leaks are the compressor discharge to condenser coil fitting, compressor shaft and even the odd pressure sensor can leak or an o ring has been damaged.
As for the oil a miniscule amount would have leaked or you would have found your leak already.
There are ''o'' rings at all the hose connections which should be a green color as rubber is not compatible,Hopefully your hoses were replaced when it was converted to R134A as the new refrigerant will tear into the standard old rubber ones.
Just check all the fittings are tight, you cannot top up R134A as it is a blend and will need fresh gas (adding some to just find the leak is ok as long as you are going to put a fresh charge in). I highly recommend the orifice tube be checked and replaced they have a screen that can get blocked and they are just a few dollars.
If you cannot find an obvious leak just get it recharged, you have only lost a small amount of refrigerant.. i do not believe in dyes.
Good luck
The most common areas for leaks are the compressor discharge to condenser coil fitting, compressor shaft and even the odd pressure sensor can leak or an o ring has been damaged.
As for the oil a miniscule amount would have leaked or you would have found your leak already.
There are ''o'' rings at all the hose connections which should be a green color as rubber is not compatible,Hopefully your hoses were replaced when it was converted to R134A as the new refrigerant will tear into the standard old rubber ones.
Just check all the fittings are tight, you cannot top up R134A as it is a blend and will need fresh gas (adding some to just find the leak is ok as long as you are going to put a fresh charge in). I highly recommend the orifice tube be checked and replaced they have a screen that can get blocked and they are just a few dollars.
If you cannot find an obvious leak just get it recharged, you have only lost a small amount of refrigerant.. i do not believe in dyes.
Good luck
Last edited by gerardvg; Sep 7, 2012 at 06:03 AM. Reason: more info
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
You can add a can of 134a/W UV leak detector dye added in with it. The dye is mixed with a small amount of oil allready. You will need a black light in order to see the dye during inspection.
http://www.oreillyauto.com/site/c/de...1786&ppt=C0050
http://www.oreillyauto.com/site/c/de...1786&ppt=C0050
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,237
Likes: 117
From: San Antonio Texas
Thanks. The car is originally an R134 car and I had a pro service the A/C a couple of years ago. It's been working good till about a month ago. It would cool just fine, but I could feel the compressor cycling when driving about 30 to 45. That compressor really "hits" that engine hard. I can't believe I can feel it hit so strong against a big 350 with a tugboat flywheel!
I was afraid it was going to break the belt. It's going to get fresh schreader valves and I might as well replace that oriface tube as well. It's completely empty of all pressure now. I guess pressure might have been holding the leaky valve shut till the pressure dropped below the "keep it closed" level. Thanks for the input.
I was afraid it was going to break the belt. It's going to get fresh schreader valves and I might as well replace that oriface tube as well. It's completely empty of all pressure now. I guess pressure might have been holding the leaky valve shut till the pressure dropped below the "keep it closed" level. Thanks for the input.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
OK, then you probably have the 10PA20 Denso Comprssor. This is a pretty good pump, but they do leak around the Shaft/case seals over time. I have a 10PA on both my Vette and Accord. The Accord W/240K starting leaking at the case. All 5 Case bolts were Hand tight. New seals plus shipping was under 50 bucks.
I would deffinetly use Dye to establish were the leaks are before tear down.
I would deffinetly use Dye to establish were the leaks are before tear down.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Just go to a shop and have them go over it with an Electronic Leak Detector. It's the only way you'll find an Evaporator leak - which is quite common for any GM. Takes all of 5 minutes and they'll want the big bucks to fix it, so most can do a leak check for chump change. You should also put a manifold gage set on it and check operating pressures. Some cycling is normal - specs are 8 or less per minute at 70 degrees, though at the temp it shouldn't cycle. Operating pressures are where you should start your diagnosis. Have the engine at 1200 to 1500 rpms; system on high; main radiator fan or fans running. You could post those pressures here or all the Shop Manuals have ballpark numbers for average temp/humidity.
Nippo 10PA20C compressor was used on the '88 up - Harrison R4 on everything before that. It probably only matters in terms of replacement cost.
Nippo 10PA20C compressor was used on the '88 up - Harrison R4 on everything before that. It probably only matters in terms of replacement cost.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
I would just add a can of 134. You won't need to add oil unless you change the compressor, evaporator or condenser. When you add the 134 in, you can check the pressure with the handy dandy manifold gauge that you can buy for a few bucks.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,237
Likes: 117
From: San Antonio Texas
Yes I've got the Denso compressor and everything is clean and dry all around it, not a sign of oil or dirty residue anywhere, so I think it's OK on that side. There was a little oily, road dirt around both the high and low pressure ports on the passenger side, but I couldn't really tell if it came from inside or was just outside road oil. I haven't seen any signs of a true leak area. I suspect the low side port cause that's the cap I took off the other night when I was inspecting things and the inside of the cap was a little oily.
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Le Mans Master
Joined: May 2006
Posts: 7,708
Likes: 266
From: indy indiana
My wifes AC would work great for about a week, then wimp out. I bought a few cans of stuff over a month or so, same kept happening. ( The first I bought was a kit with a gauge. I finally ended up going to auto zone and buying a leak detector kit for around 15 bucks or so. Came with a pair of yellow sun glasses, a pen flashlight/blacklight, and a can of refridgerant with leak dye in it. Worked great, replaced an "O" ring, refilled the system, ..that was two years ago..still working today.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,237
Likes: 117
From: San Antonio Texas
Didn't get around to a report on the fix.
The system was 100% out of pressure so there was no spewing when I took the old schrader valve out. I bought a little bottle of leak dye and put about 1/4 of the bottle in with an eye dropper and then put in the new valve. It sat for a couple of days till I could use a friends vacuum pump and we pulled the system down, so the dye settled down in the pipe pretty far before we pumped a vacuum on it. Put in almost 3 cans of 134 into the system and everything seems to be OK. Cools great & No leaks detected yet and it's been a couple of weeks. Haven't driven the car much since I added the 134 (just been too buisy lately). I have a UV light that lights up the dye very bright yellow/green color (REALLY BRIGHT) so I would see it if there was a leak. Got some of that dye on my finger & thumb when I put the cap back on the bottle and cleaned out the eye dropper. You can't see it till you put it under the UV light but my hand glowed for two days. That stuff doesn't wash off!
The system was 100% out of pressure so there was no spewing when I took the old schrader valve out. I bought a little bottle of leak dye and put about 1/4 of the bottle in with an eye dropper and then put in the new valve. It sat for a couple of days till I could use a friends vacuum pump and we pulled the system down, so the dye settled down in the pipe pretty far before we pumped a vacuum on it. Put in almost 3 cans of 134 into the system and everything seems to be OK. Cools great & No leaks detected yet and it's been a couple of weeks. Haven't driven the car much since I added the 134 (just been too buisy lately). I have a UV light that lights up the dye very bright yellow/green color (REALLY BRIGHT) so I would see it if there was a leak. Got some of that dye on my finger & thumb when I put the cap back on the bottle and cleaned out the eye dropper. You can't see it till you put it under the UV light but my hand glowed for two days. That stuff doesn't wash off!