How do these numbers look at 100 degrees outside and 21% humidity? I want to make sure i didn't overcharge it. Thanks!
2000 AC Low and High Pressure PSI
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Engine was at 1600 RPM.
Yes, that's a bit too high. Should be around 35, unscientifically speaking.
Mike6158
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From the service manual
So my 2000 is not cooling like it used to. I don’t have gauges and was wondering if a can of Freon from the autozone would do the trick? I have zero experience with ac systems. I am sure the dealership will find a thousand dollar bill in it if I take it to them. Any help would be appreciated
Mike6158
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Gauges can be had for relatively cheap on Amazon. Connecting is easy (quick connects). The connections are two different sizes so that can't be messed up. I wouldn't add refrigerant without gauges
Something like this? Thank s in advance
OrionMotorTech 5FT AC Diagnostic Manifold Freon Gauge Set for R134A R12, R22, R502 Refrigerants, with Couplers and Acme Adapter
Mike6158
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Yep, that should work. The yellow hose is for adding the freon. For some reason the hose sets don't usually come with a resealable can tap valve (don't see one in the pic either. You can get that at Autozone or wherever you buy parts. You need R134A refrigerant
Thanks
I just had the timing belt and thermostat done. Is that connected in any way to the system?
I just had the timing belt and thermostat done. Is that connected in any way to the system?
Mike6158
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I wouldn't think so. Unless they disconnected some lines or power connectors when they pulled the radiator.
Can you hear the compressor kicking in and out? Open the hood, face the engine, the compressor is on the lower drivers side front. There is a definite sound when it kicks in and the engine rpm usually drops a little
Can you hear the compressor kicking in and out? Open the hood, face the engine, the compressor is on the lower drivers side front. There is a definite sound when it kicks in and the engine rpm usually drops a little
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- #11
Thanks. I saw that fsm page on another thread, but am not sure how the higher, 100 degree ambient temp outside should be factored in. What year is that fsm page from? I have found different info on correct psi in various places, all show different psi for different outside temps, and all show higher than 35 psi like that fsm page shows. I also came across a tutorial that said to rev engine at 1500 rpm. I guess I should take another reading revving at 2000. Originally, i used a low pressure gauge only and followed the instructions on it, which said charge low to 47 psi for the temp that day. i added most of a 12 oz can of 134. But after doing more reading realized the low pressure only gauge is inadequate and i may have overcharged it. I returned the gauge to autozone and borrowed the complete manifold gauge, and got the reading shown in the pic. So...i need to decide either to leave it, or let some out. Any experienced opinions are greatly appreciated. Thanks
Mike6158
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That was from my FSM. 2000 LC. 100°F out makes it higher but see that innermost red dial on your gauges? That's what the temperature will be at that pressure. Discharge is not after the condenser, it's before and compressing the freon superheats it, which is why we need a condenser to lower the temp and condense the refrigerant. The higher the pressure the hotter the temperature and vice versa. The compressor will have a temperature (or pressure) limitation.
Mike6158
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I'd let some out from the low side, easier to control and you won't heat your lines and gauges up, and watch the discharge pressure until it's close to spec. It won't take much.
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Thanks Mike, Its a little cooler out now-about 96 degrees. Revving at 2000 made a difference; low was reading about 41 psi. I let some out through the low as recommended; took it down to 37.
Mike6158
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Sounds good. Lowering the discharge lowers the suction and that should make the air coming out of the vents a little colder. 37 is 44-ish degrees but it's not a 1:1 due to inefficiency in the evaporator (air to freon heat exchanger)
Impossible for us to say with any certainty if those pressure readings mean anything or not. Not having any other information to go by. Pressure readings are 'helpful' to diagnose what is going on with your A/C system but don't be fooled into thinking when you hit a certain pressure 'window' that all is well.
The pressure recommendations assume the rest of your cooling system is up to par. For instance, you could be undercharged (by weight) but have poor airflow (fan clutch, condenser fan, dirty condenser, dirty radiator) and you would see elevated pressures (along with temperature) and poor vent temps.
So, before I offered any advice..I would want to know why you are testing your system to begin with? Presumably inadequate vent temps?
If that is the case before...you grab a can of refrigerant to 'pour in the cool', you should check to see that your coolant temp is correct for the conditions at hand. That will give us a good idea IF there is proper air flow through the condenser and radiator.
IF you have proper air flow..then we can move on to using the manifold gauge set to get an idea of what is going on.
IF you see that both high and low side readings are LOW, we might reasonably assume a low refrigerant charge (you have a leak and some has escaped). Refrigerants are not 'consumables' (like engine oil) so the only way to have a loss is because of a leak.
Clearly, the remedy in that instance is to determine where and how bad the leak is and decide whether to just add refrigerant or fix the leak(s) first.
The pressure readings you show for the ambient cited (assuming your cooling system is OK) is a bit high. The high side being more askew than the low side...suggesting air in the system. Has the system been worked on in the recent past (topped off)?
Also, without benefit of vent temperatures....it will be difficult to optimize the refrigerant charge. Significant changes in vent temps can be felt by hand...but nobody has a calibrated hand, so pick up an inexpensive vent temperature dial and monitor it that way.
Mike6158 wrote:
Yep, that should work. The yellow hose is for adding the freon.
Yes, not that there is anything special about hose except it's color. More importantly the OP needs to know (if he doesn't already) that the center port on the manifold set is the service port. It is used for more than adding/charging the system. It also used to evacuate the system (of refrigerant) and when pulling a vacuum on the system prior charging. Some Manifolds have two service ports.
For some reason the hose sets don't usually come with a resealable can tap valve (don't see one in the pic either.
Pretty common. The manufacturers have no way of knowing what kind of can tap you need/prefer or if you are charging from a bulk tank, so they leave that up to you.
Yep, that should work. The yellow hose is for adding the freon.
Yes, not that there is anything special about hose except it's color. More importantly the OP needs to know (if he doesn't already) that the center port on the manifold set is the service port. It is used for more than adding/charging the system. It also used to evacuate the system (of refrigerant) and when pulling a vacuum on the system prior charging. Some Manifolds have two service ports.
For some reason the hose sets don't usually come with a resealable can tap valve (don't see one in the pic either.
Pretty common. The manufacturers have no way of knowing what kind of can tap you need/prefer or if you are charging from a bulk tank, so they leave that up to you.
No. But that is not say someone didn't damage a line or disconnect a wire.
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- #19
Flintknapper, Thank you! Your advice is very appreciated. You are truyly an authority on this site. Yes, i noticed lower air vent temps than normal, so I originally just checked the low, and based on the psi recommendations on the low gauge i originally used, added freon. I see my high pressure reading is too high, and I may have introduced air into the system. I think I made a mistale when I started the engine and ac system with the manifold valves open instead of closed. When I was later discharging through the the low, it seemed like mostly air was coming out. What do you recommend for evacuating air from the system, and what do yoy recommend for cleaning the condensener and radiator? I will get a thermometer for the air vents and post back when i get the chance. I am headed across the desert tomorrow going through Vegas on my way to Utah for a family vacation. Can running the ac with the high psi in the high pressure side damage the system? I won't be able to clean the condenser or radiator before the trip, but I could try to bleed air from the system in the am of possible. The ac is running cooler than before. Thanks again, Ted
Ted, you are fine. The pressures are only marginally high, I would expect no problems to occur from that. Enjoy your trip and we will deal with it when you get back.
