Help with AC Please. 2009 Prius. Blowing not cold air.

congrats!

 

Congrats! New for fall! Pumpkin Spice Air Conditioning in SunMan’s car!

 

Great work! I doubt even at a dealer they could solve this without trying changing parts multiple times.

 

For information, with ambient air temps of 86 - 95 degrees F, fan speed high, temp at MAX COLD, all doors open: low pressure spec is 22 - 36 psi while high pressure spec is 199 - 228 psi.

I hope you will find your air conditioner continues to work properly next spring and summer. I am wondering whether the compressor is not operating quite right given the relatively high reading on the low side and the relatively low reading on the high side.

 

Why don’t you put your car in a garage that you can heat it up somehow and bring the temperature to 75 or 80 degrees and then test the car AC.

 

This has been an interesting and timely thread. My 2005 Prius started blowing warm air just as the weather started to cool down. I’m disabled so I can no longer do my own work but have a local mechanic here in Katy Tx that does the work even if I supply my own parts.

After doing a die test I had the leaking evaporator problem rather than a bad compressor. This requires an almost complete disassembly of the dash, major pain.

I sourced the new series of denso parts from parts geek and got a Black Friday discount ( who knew car parts could be bought on Black Friday for a discount). The new evaporator design is supposed to address the mold/mildew issue that the original or catalog b parts have. I went ahead a bought the denso oil $158 for 16 oz!

It seems you have to replace the condenser if you open the system to air so I have the new model denso condenser as well ( it’s supposed to be more efficient in hot weather).
It turns out the A/C oil they use is extremely hydroscopic and even 30 min exposure to the air can ruin it.

I hadn’t been able to find up to this point anyone that had used the third party oil so it’s good to hear that it didn’t immediately blow the compressor. I’ve seen 3 Prius get scraped because someone bought a can of 134a with the wrong oil and smoked the compressor on first start.

So I now have 12 oz of Toyota oil in a vaccine sealed bag with desiccant sealed in with the can.
If anyone is in the Houston area and needs 3-4 oz drop me a message.
With our first warm day today the a/c if frosty and I hope it stays that way a long time.
My cost was just over $1300 for part and labor. That did include all new seals and a new expansion valve as we had to tear the dash down to the bones.

 

Thanks SunMan,
Excellent work and diagnosis.
I have experience with light aircraft refrigerant air conditioning,
Which can be more difficult to sort out than auto systems.

My gen2 PRIUS had low cooling this summer.
I live in northern Australia with ambient temps of 30 C plus and high humidity.

I took a refrigerant approach first, and with gauges fitted , sure enough high side down to 90 psi.
Low was very low 10 psi or so.

In Australia we can only purchase aircon gases with a license. My license had expired as it was from another state.
Alternative is an Australian product called “Hychill” “minus 30”.
No license required and can be used to replace and top up R134A.
Also normally a smaller amount is required

 

First attempt at top up, pressures were unusual from what I have seen in the past on many types of cars.
Trick with these systems is the gage readings before, during and after a/c servicing can reveal a lot of diagnostics about the system.may pay to take photos of gages along the way.

Found filling thru low side was very slow, a trade tip here is to place the gas container in a warm place near the exhaust in engine bay , this raises the gas pressure speeding up gas charge.
In the workplace we would use digital scales and open the liquid tap and charge by weight, in the PRIUS 450gms.
Similar qty to most small cars.
With a disposable container you can do the same by turning container upside down.
But compressor CAN NOT be turning for liquid charging.

With high ambient temps , 30 C plus, it can be difficult to get a full charge.
Another trade trick is to spray water onto the condenser, this reduces high side dramatically by 30 psi plus.
With controls set to full cold and doors open, need fan at highest setting charge to nominal pressures 25 psi low
And 220 psi high.
Repair manual says you may need to add 100 gms after sight glass clears.
I noticed this as well, pressures were getting close but sight glass was almost empty.
Keep charging gas thru low port and spraying water onto condenser, the system changes pressures as it
Cycles. May pay to shut car off and check again after 10 mins.
Finally got nominal pressures 20-25 psi low and 225-230 high.
Seemed low press drops slower than high increases during final charge. Different to most small cars
I have serviced.
Sight glass cleared and A/C the best cooling it ever has been

Another tip for evacuating system. If you purge the system with dry nitrogen, 99.9% of moisture will be removed from the system. Connect 100 psi nitrogen to the line that normally connects to charge can.
Open just the low tap on gage manifold and crack the high gauge line at the manifold, purge for 10 mins min.
Then tighten high line, fill system to 200 psi nitrogen, shutoff low tap and let it sit for another 10 mins.
This is an effective static leak check of system, it I drops check all fittings with a bubble check / detergent spray.
Connect vacuum pump and evacuate for 15 mins, don’t have to let the nitrogen out as vac pump will extract this then go into vacuum.
Vacuum needs to be close to -30 inches. Tip here is only the very expensive pumps can effectively boil water out , so our nitrogen purge has already removed the moisture and anything foreign for us.
Saving hours on a vacumpump which auto shops cant afford 6 hours under vac.
Always evacuate by opening low tap, if high is open oil will be removed from system.
Again shut off low tap, wait 10 minutes and we have now static leak checked system under pressure and vacuum.

Most gas containers now have dye in them, to find any tiny leaks , use an ultraviolet light, at night
If it’s just a low powered torch type.
To find evaporator leaks, catch 200 ml (half a cup) of the water that drains onto ground in a glass jar.
Shine the ultraviolet light thru the glass and you can tell if evaporator is leaking gas.

Regards
OZ

 

So my PRIUS now cold as it’s ever been BUT
Noticed on a longer drive , 20 mins plus, it was reducing both temp and fan output from Venezuela S.
This is normally due to dust and lint accumulating on evaporator matrix and freezing into ice.

Will remove blower fan and try to clean evaporator.
Dreading the idea of removing the who,e cooling unit and dash, as I did the dash a year ago to replace
Digital speed display. It was a monster job and quite difficult.

Has anyone removed the cooling unit/evaporator ?

Trying to get the scope on doing this .

Hopefully can clean evaporator enough with blower fan removed

Regards
OZ

 

using the nitrogen to pressure test that’s a good thing.

But nitrogen by itself does not remove moisture. Nitrogen dose displaces air that contains moisture. But the actual moisture itself is contained deep under the surface film of the oil and in the pores of the metal. This can only be removed by deep vacuum. vacuum that is usually below 500 µm. but you’re lucky if you live in a place that is 30+ Celsius it’s much easier to remove the moisture with slightly less vacuum in a shorter duration of time. Especially if you run the engine turn the heat all the way up in the cabin in defrost mode. This will run 140F plus degree air over your evaporator and with a closed hood and running engine you’ll be well above 140° on all the AC components lines compressor condenser aiding the moisture removal under vacuum.

Even some of the cheaper vacuum pumps can achieve very low vacuum in the low micron range. But you only can know or measure it using a micron gauge.

As for topping off refrigerant it is never recommended and you don’t use pressures to determine whether his system is full or not. This can sometimes really fool you and give you false information.
Same goes for the method of using the site glass when it’s clear and just randomly adding more refrigerant.

When using alternative blend gases that are not actually R134A. They are close to the same pressure and temperatures shown on the PT chart but they do drift and are different. And some of the blend gases that are substitutes sometimes have a gas property called glide which will really give you some funny numbers that don’t correlate with what you think you’re supposed to see on your gauges.
And when you use blend gases that are a mixture of gases that have slightly different bubble points at different temperatures you can have a completely full system and still have bubbles depending on the bled the gas. Also going to the other side of the extreme you can have a low system with a clear sight glass.
I’ve read some of the forms in Australia for air-conditioning and I know they have a problem with butane or propane being substituted for refrigerant. Many of the professional air-conditioning mechanics complain about this problem DIY guys topping off blend gases on top of R134a and contaminating the gas. And when you do this you get a completely different type of gas that has different pressure temperature properties that do not follow any of the rules of the PT chart. Go on YouTube and look for this following title will bring you exactly to the video.
(Warning Prius owners do not let anybody top off your refrigerant)

also on YouTube search for the title.
(pt 1: crucial refrigerant charge 2014 Prius)
This will take you right to the video showing you just a small quantity of refrigerant in one refrigerant gauge hose what it can do to the pressures and operation of the air conditioning system.

This is why you don’t guess you don’t estimate you don’t try to use experience you don’t try to use a PT chart pressure temperature charge for refrigerant on a variable type compressor that uses sensors on the electric compressor in any fact any variable type compressor system.

Just remembered one of the other statements when using a vacuum pump you can vacuum out of the high side and low side you do not remove oil when you do a vacuum vacuum pumps do not remove oil.

Now on the other hand refrigerant recovery machines will remove the refrigerant oil if you recover refrigerant from the high side especially when the high side service valve is located on the liquid side on the line connected to the expansion valve this line contains a lot of liquid that is also has a higher concentration of refrigerant oil in it.
If you are getting a lot of oil out of the high side refrigerant line when you’re pulling a vacuum using a vacuum pump that means somebody grotesquely overcharge the system with oil when they serviced it before or replace parts. Where they kept topping off the system with those little cans from the auto parts stores that contain oil inside of them so every time the system keeps getting more oil added to it than the vapor refrigerant leaks out without losing the oil and the person adds another can and then another can and then another can stacking up the oil concentration overtime.

And if you really wanted to learn and be more accurate at your refrigerant testing you would learn more about charging using superheat and sub cooling. Not pressures !!!...

And by the way it takes less than 10 minutes to recover the refrigerant out of a Prius in those warm temperatures and it takes less than 30 seconds to recharge the system with a full capacity of gas so what’s the loss it’s fast and easy and there’s no guesswork when you’re finished.

 

it takes less than 30 seconds to recharge the system with a full capacity of gas so what’s the loss it’s fast and easy and there’s no guesswork when you’re finish


After I do a full evac what is the procedure to charge my 2007 in 30 seconds? Please tell me

 

Well ended up I had overcharged system.
I use Hychill, an Australian product to replace R134A.
It has a lower high pressure so, more like the old R12.

anyway got hold of a Toyota diagnostic tool, and saw evap temp almost reaching 0.
Pretty crazy as aircon ECU is looking for a target compressor speed, not actually relying on feedback from refrigerant system.
As you back off accelerator evap temp can drop from 5-6 C to zero or below and start to freeze up evaporator
Matrix.



Regards OZTRAX and now also XLAND (email got hacked)

 

I never tell anyone the exact answer to that question. That would be too easy and you learn absolutely nothing. I give the answer the exact same way my father had me do at the age of 12. Acquire information, Understand & put all the information together and give and explain step by step answer to him. Then my father would let me show and prove my theory ? Hypothesis ? or Fact !. There was no youtube, no internet, no videos, only paper books. Gas laws - Wikipedia
Entropy (classical thermodynamics) - Wikipedia

you will answer your own question in the two links above its so simple you will hit your self in the head. If you answer your own question along the way you will learn so much more.