Help with accumulator

[LVExp]

After much testing with manifold gauge and I’ve dye I found the leak in the evaporator. While I was at it I figure I would replace the accumulator since it was starting to rust and only $18 from RockAuto.

Got everything put together and did a vacuum test. Got to -25PSI. After removing the manifold gauge and waiting an hour it was back to 0. Draw it down to -25PSI again and this time when I removed the manifold gauge connector from the low pressure test port I heard a noise. Put my finger over the port and felt suction.

Held my finger over it for 10 min and it kept the vacuum at -25PSI. Removed my finger and it was back to 0 PSI in a few minutes.

Ok so schrader valve is bad, it happens. Off to AutoZone for another accumulator. Hooked it up, same exact issue. Low pressure test port is leaking under vacuum. Tried installing the cap but it’s not tight enough to hold pressure.

Did I do something wrong to have two do the same exact thing? Will it be different when it’s under positive pressure? I don’t want to waste the $ charging it to see or venting the refrigerant.

Ideas?

 

[LVExp]

Since the old accumulator hadn't failed, was only starting to rust on the exterior, i reinstalled it and put it under vacuum and it holds -25PSI with no leaks including at the low pressure testing port like the two new Four Seasons units.

Can anyone suggest a better brand then Four Seasons? Rock Auto offers units from UAC and GPD? Is it worth the extra $309 to get a Motorcraft unit?

 

[Fix4Dirt]

ive liekd fourseasons IMO, they were pretty good for the price. the MC is 309 more... HOLY GEEZZ!!!! not sure if thats worth it though.

 

[Supertech22]

Leave the gauges on. The schrader valves are meant to keep pressure in. Not keep it out. They are like a check valve. Shut the valves off and it should hold pressure. Leaving them on you can also observe the pressure drop.

Did you try pressurizing the system? The Schrader valve should stay shut with pressure behind it.

 

[LVExp]

ive liekd fourseasons IMO, they were pretty good for the price. the MC is 309 more... HOLY GEEZZ!!!! not sure if thats worth it though.

I've also had good luck with Four Seasons on multiple vehicles, this is the first and only issue I've had. The fact that it's happening on two units from different lots and warehouses has me concerned.

 

[LVExp]

Leave the gauges on. The schrader valves are meant to keep pressure in. Not keep it out. They are like a check valve. Shut the valves off and it should hold pressure. Leaving them on you can also observe the pressure drop.

Did you try pressurizing the system? The Schrader valve should stay shut with pressure behind it.

Leaving the gauge and closing the valves on the manifold gauge doesn't do anything but slow the leak.

I haven't pressurized the system yet cause i didn't want to waste the $ on or vent the refgritirant if it's not working as expected.

 

[Fix4Dirt]

I've also had good luck with Four Seasons on multiple vehicles, this is the first and only issue I've had. The fact that it's happening on two units from different lots and warehouses has me concerned.

hmm... i have a fan motor sitting in a box from them... fingers crossed on that!

 

[Supertech22]

Leaving the gauge and closing the valves on the manifold gauge doesn't do anything but slow the leak.

When you pull a vacuum, do you let the pump continue to run for a minimum of 30 minutes? This causes any moisture in the system to be boiled off. Then shut the valve to the pump off leaving the hi/low ports open.

You had the system open to ambient air. The air is moist. The "slow leak" may be the moisture expanding causing a decrease in vacuum.

If you still have a loss of vacuum with the gauges on 30 minutes after the pump is shut off, then you have another leak. Check your gauges for leaky o rings. Check any fittings you had apart for rolled o rings/tight connections. <-- I've had this happen.

It's also a good idea to replace the drier at this time too as it is probably contaminated with moisture and no longer doing its job.

 

[LVExp]

After some more research i found out you can also test the AC system under positive pressure using an air compressor. I reinstalled one of the Four Seasons accumulators that was leaking under vacuum and charged the system to 120PSI. It held this for 4 hours.

I vented it, vaccummed it, charged it, and so far it has held!!

 

[C420sailor]

Good job.

As mentioned, schraeder valves will not hold a vacuum. They’re designed for positive pressure only.

I keep a small bottle of nitrogen with a regulator and hose attached in my garage. Good for odds and ends like charging shocks/struts, and pressure testing AC systems. An air compressor will do the job, but you have to make sure you pull enough of a vacuum for long enough to get all the moisture out that your compressor pumped in. N2 isn’t perfect, but it’s way more dry.

Pressure testing is the way to go. Many leaks can sneak by a vacuum test. The nature of many leaks/failures make them susceptible to ‘self sealing’ when you apply a vacuum…then they’ll leak again once you charge them. Dirt on the outside of components can have the same effect, getting pulled in as a tiny plug…and also contaminating the system.

Pressure test first, then pull the vac