Pulling a vacuum on 2008 mercury grand marquis

[AircooledAndy]

Hi. New to the forum. I'm trying to pull a vacuum on a 2008 mercury grand marquis. I have an orion motor tech 3.5cfm 1/4hp vacuum pump and a set of 3 way gauges. I know I have a leak, can't hear it but it doesn't hold vacuum. I replaced the accumulator and added pag oil to the accumulator to replace the rusted out and leaking one. I also changed Schrader valves and changed orings at all the connections. This car had not had the AC working in a number of years and it wasn't until I was tipped of by a Youtube video that accumulators on these cars are a known weak spot that I decided to give it a go. I also pulled the office tube and cleaned it, it wasn't terrible. I bought some 134a replacement which is a HC based r12a. When I try to pull a vacuum it comes down fairly quick, maybe a minute or two. Withe the vacuum pump on it holds vacuum. And I know it's not the gauges as I can pull a vacuum on just them and it holds. As soon as I close the valves the vacuum starts to go back to 0. Slowly like over 5 minutes it's back at 0. So I know it's leaking but where. I think if it were a metal line it wouldn't be able to vacuum at all since my vac is so small. Could it be a porous hose, closes up and somewhat seals as the vac keeps up with loss, then when shut of the vac the pores expand letting out the vacuum I had. It'll go down to about 29in hg which is about right for my 1350ft elevation. I hate to put this replacement refrigerant in to find the leak as it's HC based and would be flammable. Sniffer is of no use cause the system lost its charge years ago. any ideas? I noticed high pressure lines have some sort of can on them. Is this a filter?

[B52bombardier1]

I had this same situation on my El Camino. It would hold a vacuum but then leak like a sieve when the least little bit of fresh refrigerant was added. My leak was at a connector crimp and was easy to see with compressor oil residue and UV dye at the crimp.

I think the "can" you refer to is a "muffler" to quiet down fluid flow in the lines.

Rick

[tbirdtbird]

1. "When I try to pull a vacuum it comes down fairly quick, maybe a minute or two"
Are you sure your couplers are fully engaged to the system? There is no way a system actually connected to vac pump can pull down that fast. A proper vacuum would require at least an hour , longer is better. The vacuum portion of the blue gauge is not accurate at all. You may only be pulling down your gauge set. Some of the cheaper couplers are not made to the SAE spec and will not depress the cores fully or not at all.
2. I gather 134 is not available where you are?
3. What was wrong with the original system? Was an accumulator leak every actually determined, or is it supposition? Did the compressor crap out?
4. The comp shaft seal is a common location for a leak. Remove the belt and put a shower cap over the comp over night. Then poke a hole in the bag and sniff....see below
5. I am of the opinion that you will need to sniff in order to find your leak. If you are certain your couplers actually couple, then you can introduce a can of your refrigerant into the hi and low sides by using your manifold and then use a sniffer. I am not sure if the standard refrigerant sniffers will detect HC, you would need to check the documentation. If all you have to work with is HC based refrigerants there, then flammability becomes a way of life. Suppose the system were tight and a leak developed under the hood later while you are driving along? There is risk with HC no matter how you cut it. Don't smoke!
6. Alternatively you could connect up a bottle of dry nitrogen and using soapy water do a bubble test. You would need the nitrogen regulator to do this.
7. Do you have a pic of the orifice tube before you cleaned it? If so post a pic so we can see just how dirty it was.
8. Since the system is not operational you will not be able to use dye. If you get to the point of being able to charge, introduce dye so that you can potentially find leaks later
9. The can is indeed a muffler.
10. I really do not think your problem is the pores in the hoses as you postulate
11. another common location for a leak is the evap. You would sniff the drain tube under the car to check for leaks there....refrigerant is heavier than air

[JohnHere]

Welcome to the Forum.

The first question I ask is why would you use R-12a, a hazardous HC alternative refrigerant, in a car that the OEM charged with R-134a at the factory? The latter is still readily available, it is what your car's system was designed for, and it is what will work best. So why not play it safe and keep it R-134a? Personally, I do not recommend or use any of the alternative refrigerants. And if you should have to take it to a professional A/C shop with R-12a in it, they will promptly refuse to work on it. So bear that in mind.

Obviously, the system is leaking someplace. And from your description, it's a pretty big leak in that the system loses all of its vacuum in about five minutes. Such a leak shouldn't be hard to find if you put in some R-134a containing UV dye (it doesn't have to be a full charge), run the system for a while, and then check it for visual evidence of the leak.

I disagree with a "sniffer" being useless. Even if the compressor won't run with the small amount of R-134a that you put in the system, it will still have enough pressure to leak out and for the sniffer to detect it.

The leak could be anywhere, including in the metal lines and hoses that you mention. However, I would start by looking at the compressor front seal, the condenser, and the evaporator. You can check the front seal by removing the belt and placing a shower cap or plastic bag around the front of the compressor, cinching it down so that it seals around the compressor body, and then after a short time, sniff under the shower cap or bag for traces of refrigerant.

You can check the condenser by looking for signs of oil anywhere on it or by sniffing all around, paying particular attention to the bottom since refrigerant is heavier than air.

You can check the evaporator by sniffing at the condensate drain tube underneath the car and at the dash vents with the blower on its lowest speed, even if the compressor isn't running.

Yes, the metal cans in the lines are mufflers that are designed to dampen the pulsation sounds from the compressor.

[tbirdtbird]

John, we are in agreement on all points. Do not know where the idea of a sniffer being useless came from.
He might be in Canada and can't get 134 maybe??
Dave

[JohnHere]

John, we are in agreement on all points. Do not know where the idea of a sniffer being useless came from.
He might be in Canada and can't get 134 maybe??
Dave

Right, Dave...if the OP is not located in the USA, access to R-134a might be difficult or impossible.

I'm not sure about the sniffer idea. If it's a country north of our border where people aren't allowed to buy R-134a, that could be the reason--especially if an A/C sniffer won't detect HC refrigerants, rendering such an instrument useless up there.

[AircooledAndy]

So I'm in Canada and don't have a license to buy r134a. Heck if I can get it to hold a vacuum I could take it to a shop to get r134a put in. I'd rather do it myself and use the HC based r134a "replacement" which is actually 12a rebranded..Anybody can buy these replacements of the shelf Walmart or Canadian Tire and such. As the laws are in Canada I had local parts store didn't even want to sell me pag oil. I do not believe the sniffers can detect HC and got to remember this thing did not work for years, compressor would never come on as there was no charge. I hooked gauges to it there was nothing left. Also I've had the system apart replacing the accumulator, all the orings and Schrader valves so don't think I'm gonna be able to sniff any of the original charge. As one said the vacuum came down too quick, blockage? I noticed what seems to be moisture come out of the vac pump muffler even after multiple pulls of half hour each. Infact I think it almost got worse over time.

[tbirdtbird]

What does it take to get the license there?
In the USA a license is not needed for 134 or for residential 410. For other refrigerants,
you can be licensed by several on-line entities.

[JohnHere]

I noticed what seems to be moisture come out of the vac pump muffler even after multiple pulls of half hour each. Infact I think it almost got worse over time.

When was the last time you changed the oil in your vacuum pump? If recently, did you use the oil the manufacturer recommends for your vacuum pump and not, for example, 10W-30 motor oil? Changing the oil after every second or third evacuation is well advised.

[AircooledAndy]

I took a two year diploma at college level in automotive mechanics, as part of the course I had ozone depletion certificate.Also took a year of heavy equipment mechanics. From what I understand you have to have your trade certificate ie journeyman papers to buy r134a. Its like they want you to both know what the freon does to the environment but also know the procedures to repair without venting like a fool. Ozone depletion certificate teaches nothing about diagnostics or procedures. They did teach us operation and repair in the college instruction seperate from the ozone certificate. I got out of school and didn't spend much time in the trade. That's why there's so much miracle in a can market in Canada. Sad thing is for most the problem with their AC is that they have a leak. Just recharging doesn't really fix for any long term. Canadian Tire is nice enough to offer to check if you do have a charge before they sell you the replacement refrigerant. Cars have become more of a hobby then a career. My vacuum pump is brand new first job I've ever done with it. It came with a little bottle of oil which didn't even fill full the initial fill. I contacted manufacturer and they said SAE 30 iso 100. I topped up with SAE 30 iso 150 couldn't find iso 100