I pulled my system apart today to replace hoses, evaporator, orifice, and accumulator. The consensus for oil capacity is 9 oz total for the system, but that doesn't jibe with the Ford tech manual:



Doing the math it comes out much higher:
Compressor 3 oz minimum
Accumulator 2 oz plus another 2 oz that I drained
Evaporator 3 oz
Condenser 1 oz
Hoses 2 oz

That's 13 oz total, and that's if you don't have 3-5 or more ounces in the compressor. So what gives?

 

They give information for a specific item being replaced with a value that won't starve the system. They do that on all the model lines, I've run into the same issue. A little extra would reduce cooling but not wear out a compressor in short order. For major repairs of several components at the same time, I believe most techs and the service expectation would use the machine to flush the system entirely and then add in the 9oz.

 

That makes sense. Thanks Jack. I feel much better about only adding the 8 oz since almost nothing drained out of the compressor.

 

For those of us that don't work on A/C all the time, it leads to confusion.

 

Now if only I could find a vacuum pump that doesn't break the bank. The POS Harbor Freight two stage 3 CFM unit only pulls 24 in-HG.

 

Try a pawn shop. Take you gauge set with you and test it at the store. Then your going to want to change the oil in it before you use it.

 

After calling about 3 dozen pawn shops, only one has something I would consider buying for $259





For another $118 I could get this brand new 6 CFM unit with a 2 year warranty:




Last night I left messages with two locals who posted adds on craigslist, but apparently nobody on CL is serious about selling anything because I still haven't heard from either of them.

 

The one I have is a Robinaire 15150, I believe 1.5cfm. I orginally bought it to use in vacuum bagging veneers, but it sees use with the A/C work. Can't tell you if its great or not, it works. It was under $175 years and years ago. They are all probably made in China.

Vacuum bag or auto A/C system, it ain't a lot of cu/ft of area.

Have you checked or sealed all the fittings?

 

I "borrowed" a 1.8 CFM pump from Autozone and it pulled maybe 0.5 in-HG less than my 3 CFM HF unit. So I returned it and got their loaner gauges and wouldn't you know, with my pump it goes past 30 in-HG in less than a minute.

My go-to gauges are also Harbor Freight. Last night I tried another gauge set I bought 20 years ago for home A/C work and it measured the same vacuum as the HF set. So the possibilities are:

1. Both of my gauges are crap - pump is good
2. Autozone gauges are crap - pump is bad.

 

Based on reviews I read this morning, Robinair used to be made in America and their high end pumps still are. All of JB's pumps are made in America, and based on their graphics I'd say they're quite proud of that fact. Trade Pro is another brand that has American made units.



Unfortunately all of these pumps are in the $400-500 range, if not more.

 

So I pumped down the system for 45 minutes, closed the valves, turned off the pump, and now I'm loosing vacuum. I would like to think its the beat-to-hell loaner gauge set but who knows. All the seals are new and there wasn't a single spec of UV dye on the condenser or compressor. Do I charge it and risk wasting $50 of freon?

 

Add a tiny amount of refringent and top it off with nitrogen.
They get you leak sniffer out and start sniffing all the system.

 

After sleeping on it, I think the place to start is with a reliable set of gauges and hoses.

If I do go that route, Sean , is there a way to charge the system with nitrogen without having to spring for a regulator and a bottle from the local welding supply?

 

I am curious why the HF stuff won't work for you?

I don't do AC work all that often, if at all. I bought the gauges and vacuum pump.

Worked out perfect with zero issues, and pretty effective and accurate IMO.

Good Luck
Joe

 

When the gauge says the pump is only pulling 25 in-HG and the spec is 29.5 minimum.....Houston we have a problem. Could be a leaky manifold or hose, bad gauge, bad pump, or leak in the a/c system. Too many what-ifs for me.

Glad it worked out for you, Joe.