High low pressure

[Mijomoore]

No sealer has been added, the system is not overcharged as no Freon has been added in several years. When I replaced everything I added the correct amount of Freon (by weight) and pressures were perfect and none has been added since. Ambient temperature was 94 degrees and high humidity. Rear air was on.

My wife’s 2011 Toyota Sienna ac performance is poor, barely blows cold out of the vents. I stuck my gauges on and high side is 300 and low side is 125. WOW, very high and possibly over charged. I have not added any Freon. If I let it sit overnight the pressure will equalize to 120 high and low. What was the ambient temp when you saw 120 120? Any ideas what would cause this?

Sealer is a no-no. Dye is fine and recommended. I would recover, test for leaks with nitrogen or shop air at a positive 150psi. Weigh in your charge at 1800rpm. Without knowing ambient temps, city, humidity, rear air or not, hard to help. You should see "around" 50psi on the low and 275'ish on the high. Those are not set in stone.

[Mijomoore]

I should clarify the system is cooling some, it will blow about 15 degrees cooler than ambient air.

The accumulator is made onto the condenser.

Grabbing the line going into the evaporator near the firewall it is cool but not cold and sweating like I would expect.

Yes both times I swapped the compressor I flushed the entire system and added the appropriate amount of oil (offhand I don’t recall that amount). I also added the appropriate amount of Freon by weight and have not added any since.

"165 degrees inlet and 132 outlet on the condenser."

Those are good readings.

Does this car have an accumulator (large aluminum canister just in front of the firewall on the pass side with a pipe in and a pipe out?
Now, are you able to get your fingers on the pipe into and out of the evap, or at least is the suction line back to the comp cold? (The pipe into the accumulator). The evap is usually hard to get to, but if you can do the finger test, it would help.
How much oil was installed with each compressor change? Was the system ever taken back to bare metal, meaning was all the oil blown out, and fresh installed by weight?

Awaiting those answers. We may be getting close to having the system vacuumed down and recharged by weight. You may have too much oil.
If you ever blow out a system, do not use shop air, it is heavily laden with water vapor. Dry nitrogen is fine and can be obtained at welding shops. And we do not pressure test over 100 psi, you can damage the coils

[tbirdtbird]

Awaiting the answers to my other questions.
BTW we generally look for the low side to be about 32-35, and you may hit 250-275 on the hi side on a very hot day

OK, we are having a terminology problem. Some pix would help enormously. Please send a pic of what you are calling an accumulator.
If there is anything AC related close to the firewall on the pass side send a pic of that also

Previously you flushed the "entire" system. Does this include the evaporator? (the underdash unit)

[Mijomoore]

Which question did I miss? I thought I addressed all?
I did flush front and rear evaporators when I swapped compressors.

Nothing ac related on the firewall, just 2 lines going into the expansion valve then from there to the evaporator.

Photo below of drier/accumulator built into right side of condenser.
attachment=0]485D4735-5100-44F5-9899-DC6BC8D94A14.jpeg[/attachment]

Awaiting the answers to my other questions.
BTW we generally look for the low side to be about 32-35, and you may hit 250-275 on the hi side on a very hot day

OK, we are having a terminology problem. Some pix would help enormously. Please send a pic of what you are calling an accumulator.
If there is anything AC related close to the firewall on the pass side send a pic of that also

Previously you flushed the "entire" system. Does this include the evaporator? (the underdash unit)

[Mijomoore]

By the way thank you very much for the help here.

[DetroitAC]

Your information doesn't make sense.

The low side pressure is NOT 125 psig if you are feeling cold pipes and it is cooling somewhat. I suspect you didn't engage the service coupler and screw down the knob or something, this pressure not physically possible with those temperature observations.

You said the pipe going to the evaporator is cold but not sweaty, there are two pipes. Small diameter liquid pipe should be hot, roughly same temperature as the bottom pipe coming off the condenser. Large pipe should be cold, what do you have?

It's great that you can measure temperature, please measure high side liquid pipe temperature and high side pressure at the same time. full blower, windows open, full cold controls, panel mode, recirc, 1500 to 1800 RPM doesn't matter that much, just something steady.

Does this minivan have a rear unit? If so, full cold, high blower

[tbirdtbird]

(repeat) We may be getting close to having the system flushed, vacuumed down and recharged by weight. You may have too much oil.
Let's see what the other consultants have to say.
OK, Detroit chimed in by 1 minute

[JohnHere]

You may have too much oil.

I wondered about that as well. It sounds as though the OP didn't take into account the oil that was probably already in the condenser, R/D, evaporator, and lines.

[JohnHere]

The low side pressure is NOT 125 psig if you are feeling cold pipes and it is cooling somewhat. I suspect you didn't engage the service coupler and screw down the knob or something, this pressure not physically possible with those temperature observations.

Agree with DetroitAC. If the ambient was 94°F and the system was cooling to about 15°F below ambient, or 79°F, the low-side pressure would have to be around 75 PSI—still more than twice what the LS pressure should be.

[Mijomoore]

Mystery solved. I went out today and made sure my gauges were at 0 and connected only the low side and pressure read 35 on the low side gauge but slowly the high side crept up to 35. It appears my gauges are leaking internally causing high side pressure to leak over to the low side gauge and increase the psi reading. It’s 90 degrees outside so looks like the system is actually low but I’m going to replace my yellow jacket gauge set and start looking for leaks.