A/C blowing warm air

Hi I too have a 2010 Prius with exactly same problem. Cold a/c early morning when outside temperature is low say 13 degrees c but almost non existent a/c at mid day when 18 degrees c outside. My a/c guy found a leaking condenser radiator so he replaced that and regassed system but still the same problem. I also noticed the drivers side central vent is warmer than the passenger side.
Did you fix your problem?
Anybody got any answers or suggestions?

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You could have a bad expansion valve or compressor.
And if your car guy said you had a leaking condenser(not a radiator) and replaced it, and you still have
the same problem, you DON'T pay for NON repair. How did he determine it was leaking? And not
possibly the seals?

 

Toyita regassed system last year. When i had bumper off to do a facelufy there was staining and attracted dirt on bottom rh triangle of condenser, i cleaned this oily dirt deposit off. This year the same area could be seen to be 'wet' and a/c was low on gas. I think it was a leak but not the cause of my erratic a/c as even recently it worked well on some days!

Posted via the PriusChat mobile app.

 

Might also want to check the actuators for the blend doors if one area is cooler than another.

Have you measured the temp coming out of other locations, like the defrost or foot vents?

 

Make sure you're not running the car in ECO setting, that will reduce the AC output.

 

High side is low:



How does the sight glass look when it's running, lots of bubbles? Ours was like that, and lacklustre cooling. Took it into dealership, paid $150 for inspection/recharge, fine now.

I'll attach the Repair Manual excerpt, includes the above.

 

You may have a clogged condenser, or the system might be over/undercharged.

Fill up the with r134a, and see what happens. If it still persists, then you got a leak somewhere in the AC system.

 

New Condenser and new drier has been fitted and a professional regas has been done because condenser was showing signs of leaking and gas was low. However a/c wS erratic before working fine somedays and it is still erratic after this work.

 

Thank you for the attached info really great.
When running there are only the ocassional bubble. When a/c isnt blowing cold the Low Pressure pipe isnt very cold at all. From the documentation it says if you turn off the a/c the fluid should foam momentarily if gas amount is correct. Mine just stops so possibly it has been overgasse? It was gassed up then when bubbles stopped an extra 100gvwas added but this was done on a very hot day in UK 30 degrees Centigrade.

 

Have you checked the cabin air filter and the function of the blend doors?

 

That was my first thought while reading the first post ... that it works ok in moderate conditions, but in extreme conditions shuts off on the high pressure limit, until the pressure comes down again.

But then you posted the 150 psi high side reading, which doesn't seem high enough to trip the limit. So that's curious. But were you measuring at the moment it shut off?

Have you ever pulled codes from the ECU? Hold AUTO+RECIRC while turning the car on. Two-digit codes show up in the HVAC display where temp normally goes. I think it remembers them for a limited time; try doing this pretty quickly after it stops blowing cold in extreme temps. (If you've got anything like we've got, you should be able to try this today )

The manual should, I believe, have some specifications about what the exact conditions should be (including fan speed and position of the car doors, and ambient temp) when doing that operation. The conditions do matter.

I think Gen 4 may have some extra air-control doors in there that affect the flow balance between driver and passenger side (don't they call it "S flow" or something?), but Gen 3 does not.

-Chap

 

That actually sounds good, what I've been used to in the past with Hondas. However, I believe Toyota though says to charge until bubble disappear, and then some more. And what with the lowish high pressure reading, maybe another clue. Read through the attachment to verify.

 

Charging with gauges isn't reliable. They should only be used as a diagnostic tool to see if you're in the ballpark and to see what high and low sides are doing when there's trouble. Gauges look at pressure (PSI). It's a moving target, depending on the vehicle and ambient temperature. You will never be sure if you added the right amount of refrigerant. What is constant is the WEIGHT you're supposed to put into the AC system. The sticker under the hood should call for 1.04 pounds of refrigerant. The only way to be sure you're adding the correct amount of refrigerant is to empty the refrigerant from the AC system. If you don't have a recovery machine, the only option is to vent into the atmosphere, which isn't legal. Then you have to pull a vacuum to make sure you suck out as much air as possible. The vacuum also makes it easier for the system to suck in new refrigerant. This you can do yourself if you have a vacuum pump or buy the cheap AC evacuator form Harbor Freight (you'll also need an air compressor). Then you can either add the right amount (weight) of refrigerant from the small cans OR if you're using a large keg, use a sensitive digital scale to weigh the keg as you add. I hate saying this, but this is one repair in which it's true... It's really better to just have a shop do this. And make sure the shop has a real AC machine. If they're just using gauges, they're not doing you any favors. How do I know? I owned a chain of auto shops for 15 years. In the beginning, we were guilty of being that shop that rolled the dice and charged AC systems with gauges. You can do all the other stuff on your own, checking for leaks with a UV light, replacing leaky components, etc. But leave the charging to someone who has a machine.

 

I changed cabin filter 6 months ago because Toyota dealers dont seem to bother, they just tick the check list. The left central vent is only 1 degree c different from the right central vent but using a digital temperature guage/probe high lights this minor difference.
The air flow control appears to work ok as does the temperature control.
Today when the ambient temperature was 26 degrees c the a/c worked fine producing between 6 and 9 degrees c from the vents. Puzzling how it can work fine one day and almost not at all on another day.

 

The pressures were from the first poster.
Holding down the two buttons for error codes gave me 00 and nothing else which i undertand means no error codes are stored.

 

Hmm. Looking more closely at the DTC list, there's a column showing which ones are "memorized" and what it takes to "memorize" them. For example, the 11 code for a weird reading from the cabin temperature sensor will be memorized if the reading is weird for 4 seconds or more. Most codes are memorized. Code 23 isn't memorized at all (weird pressure sensor reading), so I guess you only see that if it's weird at the moment you check. There are a few others on the list that don't get memorized.

Might be worth connecting Techstream and watching the live data. You can actually watch the high-side pressure (it's a real pressure sensor, not just limit switches) during operation, without having to hook up a gauge set. (Pity it doesn't also have a low-side sensor!)

-Chap

 

Strange thing happened to me this week (2010 Prius): A/C was blowing hot air until the engine reached a certain temperature. Then it's blowing cool air. Strange. Using OBD Fusion, I saw the A/C compressor won't start at all. When the coolant temp reached 91 Celsius, the radiator fans started, and the A/C compressor also started.
I've just got replaced my head gasket in a service shop, and the problem came after it. So I called them, and they suggest to check the A/C compressor signal cable plug, because it can be filled with coolant, preventing communication and maybe worse.
I've checked, and as you see in these pictures, it was full of gunk. I used an air compressor to dry out and voilá: A/C is cool again, it starts when I push the button!
Be careful not to pull out the orange high voltage cable.
Do not try - or be very careful - to use any mechanical tools to clean the pins - they are very soft, bending easily.

I hope it helps.

 

Spraying water in the engine bay, especially pressure washing, can leave water in that connection. It's like a little cup.

 

Tamas - excellent work figuring this out after speaking with the shop! I need to check to see if there's any water/coolant/gunk in my connector (2014 Plug-in Prius). I've gotten the air filter boxes off and have access to the connector BUT cannot figure out how to unclip the plug! How did you do it?

Thanks,
Dan