# Refilling AC on 2002 Ford E350 van -- needle on gauge surging.



## danomac (Sep 2, 2010)

Please note I am not an expert on this...

I have charged a couple of my own cars before and it usually does this when it's low on refrigerant.

Do you even know what the capacity is? I know when I charged my friend's Nissan after we installed factory AC it took like 3 11 oz. cans... If you have rear AC in that van it could be a lot more.

I also have a proper AC manifold though, I wonder if it reads different than the gauges on the cans...


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## user_12345a (Nov 23, 2014)

i know almost nothing about fixing cars, but this thread caught my eye.

There's a switch that cycles the compressor to keep the coil above x saturation temperature/pressure. Stops the coil from freezing.

It's there for use in cold weather and also to adapt to different fan speeds, engine rpms.

Could be that there's not enough gas in the system if it's hot and the fan speed is on high. You may be able to find a chart with the recommended high and low side pressures at given outdoor/cabin temperature.

Due to the varying conditions, probably the only accurate way to charge is to do so by weight, there may be a sticker somewhere indicating the total system charge.

Pressures alone mean little and the manufacturers shouldn't be selling a can with gauge that has a blue zone.

Keep in mind, other problems like a bad/blocked metering device can cause low, low side pressure.

Should fix leak before adding refrigerant.

Also, when starting with no refrigerant, have to pull a vacuum and to be able to pull a vacuum without introducing new air/moisture, have to fix the leak.


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## iamrfixit (Jan 30, 2011)

Difficult to accurately charge and impossible to diagnose most problems with only a clunky low side can gauge. Most likely you just don't have enough refrigerant and that's making it short cycle. That means the compressor kicks on and quickly pulls the low side pressure down below the minimum and hits the low pressure cut off switch limit. You should have an AC sticker on the fender or on the AC air box that will give you the correct charge information from completely empty. A full size van with rear air might hold 3 pounds of refrigerant or more. Still having rapid short cycling after adding a whole can means it was probably mostly empty or could be leaking out as fast as you add. 

It happens a lot but it's not really environmentally responsible (or technically even legal) to just dump freon in and hope it won't leak out. If your system is bled down significantly then you should locate the leak first. If it's bled all the way then you need to find the leak, install a new drier and evacuate the system. If the system can't hold vacuum then it's probably not gonna hold freon. 

Pulling a vacuum does two things, it helps determine system integrity and removes moisture by drastically lowering the boiling point of any moisture in the system. Once the moisture gets in the system your receiver/drier will catch it, but a system left discharged saturates the desiccant making it useless. Without evacuating the system and replacing the drier, you leave that moisture inside the system. Even small amounts of moisture can affect your AC system performance as it may freeze your refrigerant metering device or cause damage due to internal corrosion. 

I'll always vacuum an empty system first to see if it can even achieve vacuum and then hold it for an hour. If not then I pressure the system up with nitrogen and try to locate a leak with soapy water. Sometimes its very easy to find leaks, and sometimes it's really tough. Soap bubbles works best for me, I've never had any luck reliably finding leaks with an electronic leak detector.


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## Bigplanz (Apr 10, 2009)

If it has a rear AC unit, the refrigerant capacity of an E-350 is 60 oz. 40 oz with just front AC. 

I put 4, 12 oz cans in my Windstar. 54 oz required because rear AC. So, I put in 48 oz, and the front vents are blowing in the mid-40's at 2000 RPM. Low 50's at idle.

Since the system hadn't worked for 2+ years, I am pretty certain it leaks. However, for a week and a half now, the AC has worked. So far, so good. This is subject to change, of course. When it leaks down, I will check for leaks (again).

I read the EPA regulations on Mobile AC systems. Section 609 is the code reference. Basically, it states that anyone who "for compensation or consideration (barter)" evacuates an AC system, they MUST use an approved evacuation. Below is the relevant language (direct quote) from Section 609.

"The EPA's definition of MVAC "service involving refrigerant" states that MVAC technicians must recycle refrigerant prior to recharging it into an MVAC or MVAC-like appliance, even if the refrigerant is to be replaced back into the same AC unit from which it was removed. For equipment that only recovers refrigerant, proper use includes recycling the refrigerant on-site or sending the refrigerant off-site for reclamation before it can be recharged into an MVAC system. This is quite different from the HVAC Section 608 requirement for stationary (non-MVAC) air conditioning and refrigeration applications, which allows technicians to transfer refrigerant back into the unit it was removed from or into any other unit owned by the same person without recycling or processing the refrigerant in any way. This requirement is not new and has in fact been clarified in the January 1998 Final Rule summary. This requirement does not apply if the service is not for consideration, as in the case of do-it-yourselfers."


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## tireshark (Aug 17, 2014)

Thanks for all the great input everyone. I got a second can, and the instant I started filling it, the compressor stopped cycling and it is now cooling. I almost feel like something might have been wrong with the first can, but I cant say for sure... anyway, thanks again.


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