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Hi Matt,
That sounds pretty good. I have wired my front auxiliary fan with a relay that takes the compressor voltage and turns on whenever the a/c is on. Except for load on the alternator, I don't see a down side. With excellent air flow, you should be able to add more R134 without going over pressure. It sounds like you're not that far off.
Good luck,
Dave
As much as I absolutely hate being patient, I think I need to get that fan installed, see what that does for the pressures, and go from there. I ordered the same one from amazon as I have on my Durango (it sucks hard enough to pull a golf ball through a garden hose). Who knows, maybe I'll get lucky and the extra airflow solves it and I won't have to evacuate the system again (still fully prepared to do that if need be). I'll look into wiring the fan to come on as soon as the ac does too.
I'm still interested in getting a high pressure shutoff switch wired in too.
You should measure, and you may need to fabricate a mounting tab or two, but it was pretty easy on my 84, and is quiet, powerful and electrically efficient.
Good luck,
Dave
Before you reopen enverything and vacuum it again, run a garden hose of cold water over the condenser when the pressures are high. You’ll likely see the high side drop rapidly, and many times remain at or below a normal pressure. Then you can add refridgerant as required.
As much as I absolutely hate being patient, I think I need to get that fan installed, see what that does for the pressures, and go from there. I ordered the same one from amazon as I have on my Durango (it sucks hard enough to pull a golf ball through a garden hose). Who knows, maybe I'll get lucky and the extra airflow solves it and I won't have to evacuate the system again (still fully prepared to do that if need be). I'll look into wiring the fan to come on as soon as the ac does too.
I'm still interested in getting a high pressure shutoff switch wired in too.
If the system is right, pressures are not a problem to chase down/make lower.
If right, no/few bubbles visible and a proper reaction (low side pressure) from the expansion valve, and you're as good as can get. Liquid at the valve, and the valve regulates the flow thru it to maintain a temperature (not a pressure) and you get cold air..TOO cold, and the freeze switch comes into play..and thats not a bad thing.
Like I said, "bad pressure" is nearing 500psi, 250-350 may be.."normal" all things considered.
The gas will do what it will do.
The problem areas are a good CLEAN fill, and all of the various components inside and under the hood working properly.
^^
This is an overfilled AND/OR contaminated system. Overfilled can also be too much oil, which with a proper gas fill, is a lower volume system for the gas, so will look overfull.
Youre focusing on high side, when really the low side is 10-15psi too high, which..is somewhat agreeing with you that the high side is too high.
If your two fans are 100% operational (is the clutch working RIGHT?) there's no need to add hardware and chase that down...if its not 100% right, fit it, dont add more complication to a simple system you already have.
If 350 was as high as it would get fully charged at 100 ambient it sounds like that would be ok. After driving around the street a couple times yesterday then coming to a stop in the driveway I was at 400psi and that's with just 20oz in the system. With another 10oz in there I wouldn't be surprised if it was close to 500psi with the system the way it sits now. Seeing the system at 20 on the low side and 175 on the high side when first started up this morning makes me hope that the pressures could stay well within a safe range if getting enough airflow.
I would still like to get a high pressure shutoff switch that could shut down the compressor before the pressure got that close to the compressor's safety blow out point in case I'd have a cooling fan failure or something along those lines.
If 350 was as high as it would get fully charged at 100 ambient it sounds like that would be ok. After driving around the street a couple times yesterday then coming to a stop in the driveway I was at 400psi and that's with just 20oz in the system. With another 10oz in there I wouldn't be surprised if it was close to 500psi with the system the way it sits now. Seeing the system at 20 on the low side and 175 on the high side when first started up this morning makes me hope that the pressures could stay well within a safe range if getting enough airflow.
I would still like to get a high pressure shutoff switch that could shut down the compressor before the pressure got that close to the compressor's safety blow out point in case I'd have a cooling fan failure or something along those lines.
Your existing blow out valve is set to do just that...but pressure will shut it all down via the switch before it gets that high too.
So the part number in that post (1H0959139B) looks to have female threads. Maybe it would screw onto the high pressure service fitting, but would probably stick up too far and hit the hood.
The pressure switch on my car looks more like this one below and screws directly into the side of the drier. Unfortunately there is no schraeder valve there.
Something like this seems like it could work. It claims to be both a high and low pressure switch and has an adapter to screw into the drier. It doesn't specify the pressures it operates at though. https://www.ebay.com/itm/Air-Conditi...5a0c%7Ciid%3A1
So the part number in that post (1H0959139B) looks to have female threads. Maybe it would screw onto the high pressure service fitting, but would probably stick up too far and hit the hood.
The pressure switch on my car looks more like this one below and screws directly into the side of the drier. Unfortunately there is no schraeder valve there.
Something like this seems like it could work. It claims to be both a high and low pressure switch and has an adapter to screw into the drier. It doesn't specify the pressures it operates at though. https://www.ebay.com/itm/Air-Conditi...5a0c%7Ciid%3A1
TBH, the safe operating limits for an AC system are not unique to any one car. I cant say that with 99.9% certainty, but its all off the shelf hardware...customized for a specific mounting, if that isnt shared also.
A certain pressure is needed to flow oil, and too much is the same way too much.
So I just looked up the part number of that behr switch from that photo and it actually might be what I need. It is part number 1248208310 and appears to be both high and low pressure. It looks like it's high pressure shutoff is 28bar/404psi and low shutoff is 2bar/29psi. That might be just what I need.
So I just looked up the part number of that behr switch from that photo and it actually might be what I need. It is part number 1248208310 and appears to be both high and low pressure. It looks like it's high pressure shutoff is 28bar/404psi and low shutoff is 2bar/29psi. That might be just what I need.
29psi is kinda high for a shut off...35d aint that cold...I mean..it is, but, thats above what your should see. A freeze-switch-less system might do that...I wonder if that poster that did that is still round.
2bar is above normal operating pressure for out systems.
05-27-2019, 02:46 PM
