R-134a Manifold Pressure
 

Does anyone have access to Ford tech data that can pull the A/C pressure chart for the 2015 3.5eco? I could only find generic R-134A data online, and it's conflicting data, charts range from 150-170 to 225-250 psi at the 80ºF temps we had yesterday. Our oldest vehicle (2010 Fusion 2.5L) was at 150psi. The 2013 Escape 1.6L and 2015 F150 3.5L were about 170psi. Only the Fusion felt week, but I brought all three up to about 220psi where all three seemed happy to push mid 30's out the vents.

Doors and hoods open, max a/c, recirculate.

2015 2.7 AC, But should be close if not spot on,

Regardless of the engine type they should all have the same systems. IE the same compressors run the same evap and same condensors - are based on the cabin size. IE all crew cabs have the same parts - 2.7L, 3.5L. 5.0L - etc etc

as far as I know they are all the same.

Now note the chart - I assume here you are quoting the high side pressures - what were the low side pressures? (discharge or suction side if you want those terms). the low side being too high can be damaging - lead to more leakage. and it's the pressure differential that is as important and the max pressure reading.

Hope that helps matters.

Yeah, if you're going to mess with that, you need to monitor BOTH high and low sides at the same time with the correct equipment, and add refrigerant thru it, to make sure you don't introduce air into the system. And depending how much refrigerant you add, you might need to add a proportional amount of lubricant too. Unless you buy the proper equipment, that kind of job is better to leave it to the pros :).

Low on all three were low to mid 40's.

I'm disappointed to see the high pressure range that low. My 95 SHO was up to 230ish IIRC, I ran it at the max range high, and adjusted the low side sensor to 20psi. I know the variable valve systems don't need to drop as much on the low line as they maintain an average pressure rather than how the low side cycles up and down with compressor operation in an orifice tube system, but it seems they left a bit on the table on the high side.

I wonder if they are holding back on the pressure to consume less energy for CAFE. Seems they have gotten to the 'every last tenth of a percent counts' point with installing shutters in most of their vehicles (The shutters in our Escape are pretty small compared to the F150's).

YOur 95 SHO was still using R-22 refrigerant from the factory. Since around 2002 everyone swapped to R134 and today you see it as R134A,C,F,etc Or Synthetic R134.

basically the class of chemicals that are - R 134 are cross compatible though.

Meanwhile because of the change in chemical - changes it's entropy values etc etc - requires different system pressures, different expansion valves, larger evap . . . . . .

Basically - it's all different now.

Also and this is another wrinkle in 2010 and newer cars some have what's called a variable volume compressor - so it adjusts vs Load and doesn't putout a constant pressure when the pulley is turning. LIkewise it doesn't have a clutch either - so the pulley is always live and inside the body the "pump" is always live not cycling. HOwever it still has an electrical lead - and it gets commands from the computer to pull in or let out a swashplate that varies this compression ratio . . . . . . .

So and I think the F150 has one too - it doesn't always run ____ psi at all loads. So you really do have to run it at certain conditions to stay within the chart span. Which then means you have another variable to play with where you could over fill the system.

So please follow the tech manual. And I think you have that - and looks like you'll be on the right track. capacites and pressure might change on your other vehicles too - so look for those tech sheets also.

...

Pretty sure it was R-12, not that it really matters but just for clarification...

Don't know where you got your info about years, Napalm, but it is incorrect. The R-134a manifold I have, I purchased for that SHO. R-134a phase in began in 1992, in 1994 it became mandatory. All new US vehicles sold in 1995 had R-134a.

If anyone noticed the conditions I set, I indicated I had recirculate turned on.

At about 85ºF today, I put the manifold on. Numbers were a bit higher than yesterday due to temp, until I shut off recirculate. Pressure went up to 270psi. I recovered gas, bringing it down to an average of 215psi. right at the upper limit of the chart TMCOLEJR provided (Thank You, TMCOLEJR!).

Temp is not bad. It's not like it was before I recovered some gas, but still better than it was running closer to 170psi. I can see how being in the middle of the range (where most shop techs will set it) and not having tinted window results in inadequate cooling when idling on hot temperatures. If I lived in a truly hot state (mid 80's-90's, rarely do we break 100), I'd run another 20psi without batting an eye. As it stands, I don't have to deal with heavy traffic, and the sides and rear are tinted (something over legal, but not limo dark), so sun load isn't bad. I'm good with staying within the limits under these conditions, but I'm definitely going to run the max. We do occasionally drive to hotter climates. I'll look into the front window IR stuff, as the black dash gets pretty hot.

Low pretty much stayed at 45psi, appeared to fluctuate maybe a degree either side, pretty consistent. High fluctuated 3-4psi either side. What I didn't do was adjust the throttle to see how it varies with speed. Temp at the vents drops a good bit by the time it's at double idle speed.

The 95 SHO was R134a, as was the 94. Had two of them, one before and one after my old 89 "project".

R22 was not used.

evacuate system , pull vacuum for at least 30 minutes, add refrigerant, using a refrigeration scale, add proper amount of pag oil according to the sticker under the hood.. it is the only way.. it is a shame that
the sell refrigerant to the home shade tree person where a professional has to be certified. there is a lot going on with temperature charts, super heat values and the rpm of the engine and proper air flow across the condenser.. too much will back up into the compressor and blow it up.

My '93 Sable was R-12. I think Ford waited until they pretty much had to use R-134a (94 models produced in 94 would have had to have it, but those built in 93 did not). R-134a first started to appear in vehicles four or five years earlier, I believe.

If it makes you feel better, I was certified in refrigeration systems while I was serving. Gas, brine, even those propane systems you see in RV's. Then, one of my first jobs after serving was working for Sears as an HVAC assistant. Mad respect to those guys, HVAC work during the summer sucks major donkey balls.

The biggest issue for shadetree mechanics isn't figuring out the system, it's using the proper equipment. Too many will vent to atmosphere or won't purge because a cheap pump is $80, and they don't have $80.

Information about the systems is very available, it's the vehicle specific charts that you have to hunt for, but, like seen here, post in the correct forum, and the internet gods will provide.

All else being equal, most just need to top up on gas lost at the seals. That's why you'll find two brands/ten cans of gas Vs eight brands/eighty cans of gas with additives, an integrated gauge, and a manifold connector. Green/Yellow/Red gauges are stupid IMO, but the systems do have a good bit of overage built in. Mostly shadetrees that screw up their system just put it outside of optimal operating condition. I corrected a few dozen of those mistakes back when I would help peeps out for free.

The only damaged system I've come across was that 93 Sable I mentioned. The compressor shaft seal blew... boy, when those go, hope you've got your ****tin' pants on! The vehicle was under warranty, so I hadn't touched it. When I saw what the dealer billed Ford, being near the end of warranty, I pulled out the refrigeration books I trained on, and started searching the fledgling internet (it was 98 IIRC).

my post wasn't meant as a slam, just wanted to post the many variables in working on an auto ac system.. as you have seen, a seal blew spewing hot refrigerant oil at high pressure, is some of the dangers..high side pressures can reach 320 psi on a hot humid day it can cause injury. i'm not posting to hurt one's integrity

My diagnostic strategy is quite simple.
1) Use an identifier to be sure nobody has forced something other than R134a or something that will ruin my equipment.
2) Evacuate the system completely and bring it to a vacuum for at least 40 minutes, longer if the system has been open.
3) Add a compatible tracer dye if there isn’t any in the system already. (Many vehicles are shipped with dye pre-installed including our F150’s.)
4) Ready for this? Fill with the specified amount of refrigerant.
5) Verify high and low pressures are within specs. If they aren’t guess what? I don’t vary the amount of refrigerant, I locate the problem!
6) Figure our what brought the vehicle to me in the first place which is usually because the refrigerant leaked out. Sometimes this may take several weeks for the dye to show up, sometimes it’s minutes.

I should have been more specific as my point was that R-12 not R-22 was used in automobiles. I am unsure of what year each OEM made the change to R-134A from R-12.

R-12 switched to R-134a November 14th 1994....but some manufacturers changed earlier because they were stocking up ahead of time.

Wasn't taken as such, and stating the dangers is never not acceptable in my book. Even handling the manifold can be dangerous. I always check static pressure before anything else. An overpressure system with a blockage... compressors can build some very high pressure, I've heard of injuries resulting from failing to check for equalization before pulling off the connector.

And on my wife's escape, it's the connector that's at an odd angle, under a radiator hose, two inches from the alternator mount (I think, didn't actually look at the component, just the mount). Took me so long to get it connected, gloves weren't helpful in keeping the heat at bay.

It was mid model year 1994 where R-134a became mandatory. How do I know this? My 1994 Cavalier was produced mid-model year, and had a notice in the owners manual (and engine compartment) about the change, and it had R-134a in the system.

Yeah I was off by a few years. I had in my head the mandatory date was 98