2004 Prius A/C Not Working, Need Help With Diagnosis

When you hook up your can or gauge from the can to the 134a low side fat hose port You should see between 80 and 100 lb probably no more The minute the air conditioner compressor kicks on it's going to suck down that 80 to 100 lb to about 30 and then that being sucked down is now pushing your high side up to probably around 200ish 230 .. That's how the system works there's no high and low side when the compressor is off the high and low side will read about 100 lb on your gauge on both sides because both sides are equalized when the compressor's off

 

The thing you noticed isn't really even something different in these machines.

Something we don't always explain well enough is that when the compressor's off, refrigerant pressure is just a thermometer. If your refrigerant showed 75 psi on a gauge, that's roughly 90 psi absolute, or about 620 kPa, and you can just look on an R134a saturation pressure/temperature chart and see the refrigerant in the car was somewhere around 23 ℃.

R134a at around 23 ℃ will just always be around 620 kPa, or 75 psi on a gauge, as long as there is enough R134a there for any of it to be liquid. Adding more or letting any out won't change that pressure at that temperature, until you have let enough out that there isn't any left in liquid form. Then you'll see the pressure going down.

Start adding some, and you'll see the pressure going up, until there's enough there for some to be liquid, and then it'll just settle around whatever pressure goes with the temperature even as you keep adding more.

That's why looking at a pressure gauge to decide how much refrigerant you've got doesn't really work as well as people expect.

 

Until the compressor turns on and starts pumping, the entire system will show static pressure. That's mostly determined by temperature, and on a hot day that'll be over 100 psi.

When the system runs, you get high pressure (from the compressor outlet, condenser, to the expansion device) and low pressure (expansion device, evaporator, to the compressor inlet).

So the best way to see what's going on is to hook up a pressure gauge set to the low and high service ports.

Lacking that, use a compatible scantool to see HVAC data - or even hybrid control (inverter) data.

https://priuschat.com/index.php?posts/3290690

Posted via the PriusChat mobile app.

 

Will ping @lech auto air conditionin for additional input.

 

I would certainly replace the clock spring You could get it from a used '09 where you got the compressor and it's been changed already it'll be fine If it's not broken it'll be fine If it is well then you'll need another one or you can buy a new one for 80 bucks or something like that Make sure the red lines are lined up on the clear window when you install it It's all in the book and it's all here in pictures somewhere some little send it to you pretty quickly I'm sure.. do you not hear the compressor It makes a distinct noise when it comes on obviously it's not running because even if it was bad it would not be zero on both gauges You would at least see some kind of movement on the low side even if it was only 10 lb then you'd know it's not capable of pumping or it's so low on gas what have you If it's that low on gas it'll try to run up to 9,000 RPMs to pump nothing or pump very little of something just because that's how it will work as soon as proper gas is there it'll never need to see the 8,000 RPM or high RPM like that.

 

Yeah anything that reeks havoc on the cooling system can shut the air conditioning compressor down The computer knows to turn it off because it's getting too hot and compressor generates more heat etc etc so on and so forth so generally if your AM too fuse is good You have movement in the inverter coolant system your regular water pump is working You're maintaining fairly normal temperatures which is generally pretty easy to do in the Prius even in the summer The air should be generally speaking working or at least the compressor should come on and if these conditions are met see if you're actually getting power through the thing could be the inverter having an issue getting power to the compressor there's a board or something in there I'm not sure exactly how it all works having pulled it apart to see. But to be honest with you I've seen very few of these compressors go bad me seeing them anyway I haven't replaced maybe one and I don't think it was bad I think there was another problem but I changed it anyway because what I had was a lot newer less miles all the nonsense and I do like my hair I didn't used to care for it much now I use it quite a bit and I'm not having it broken and I do like the way it works I like it better than my belt driven setups I'd even like to put this in one of my Corollas but there's no battery there for it and so forget it.

 

if you were to get techstream, you can see what the AC system is actually doing.

 

Sometimes people run it on a Mac in virtualized Windows.

You're probably finding references to bundled pricing that includes a rather expensive dongle and a full year of activation, more like what a working mechanic shop might want. Take a look at this post.

 

You're driving a computer (actually 15-18 of them) with 4 wheels. Life is much easier if you have a good way to communicate with them.
If you're DIY you really need it. If not, shooting the new parts cannon at the car is going to end up being pretty expensive. May end up being less expensive to just take it to a good shop.

 

Or you can read the review thread at the top of this forum. There are several apps and OBD2 devices that turn your smartphone into a scantool.

Posted via the PriusChat mobile app.

 

Techstream in a VirtualBox.

toyota techstream Mac - Google Search

how I got techstream on a 64 bit pc in 5 minutes - YouTube
Toyota Techstream for ALL Windows | How to Install and get it WORKING Everytime | Landcruiser 200 - YouTube

5 min to Download + Install Techstream V12 VMware for VXDIAG Toyota | OBDII365.com Official Blog

 

Did not have time to read through the whole post only the very first one mentioning the problem, and I did watch the video with the noise.
Pressures almost mean nothing whether the system is full or empty unless the pressures are absorbently. Extreme.
If your car has not been running and you put your pressure gauge on it in the morning and it was 45°F last night when you hook up the low side you’ll probably see somewhere around 45 psi on the low side even if the system is 100% full even if the system is three or 4 ounces overcharged, you will still see only 45 psi on the low side even if you only have one drop of liquid refrigerant left in your system at 45° ambient air temperature you’ll be somewhere close to 45 psi pressure. This does not mean you are low. This does not mean you were full and it does not tell you if you were overcharged. . This is How Refrigerant response to temperature..

I know the hand if it was 80°F outside and you just drove back from the shopping mall and parked your vehicle. You now have a nice toasty crispy hot engine compartment. You have the doors and windows closed and the inside of the passenger compartment has gotten hot in the last 10 minutes might be 100° inside the passenger compartment and you hook up your low side pressure gauge, you might see 110 psi on the low side gauge and that two will be normal for that temperature of all the hot engine components because the refrigerant lines are now hot and soaked from the heat under the hood and again whether you have 1 ounce of refrigerant, or the exact, correct refrigerant charge or you had any container that contain 10,000 pounds of refrigerant but at that same temperature they will all be the same pressure so do not let anybody tell you that you can tell a full system from a slightly low system so long as there’s one drop of liquid refrigerant to a given temperature it will follow the PT chart for that particular refrigerant.

Now under that same condition if you hooked up your low side gauge and it was 80° plus outside and you’re gay tony said 30 psi you only have vapor you’re almost empty. And that too, you could tell by looking at the PT chart for the Refrigerant temperature pressure relationship..

Now let’s get to the noise in the video I could not hear it very clearly, but it almost sounds like the compressor trying to engage and you describe the fans were coming on at the exact same time. So this sounds like a not so happy compressor sound. I have posted videos on this on my YouTube channel and in my previous chat photos and video album on Prius chat.

If you have a cheap set of gauges. You can use some of your new refrigerant to purge the air out of your gauges.. because you don’t wanna hook up a new set of gauges that are filled with air in the lines to your system.

Unless you have a vacuum pump to vacuum all the air out of the gauges when you connect them.

If you could take a video of the high side and low side pressure when that sound, that sounds like a compressor tries to kick in.

Another thing you can do take a long extension bar for your socket set or a pipe or a long cylinder from gift, wrapping paper that cardboard put it down and place it to the Body chassis of the compressor and put your ear to the other end so you can hear

When the sound comes on with your ear, at the other end of either a steel rod or a long hollow tube, can you identify that the sound is coming directly off of the compressor case shell.

Because what you’re describing is a classic sign in for a ride I think I hear from your recording is the compressor trying to engage it does not the computer notices that in instantly kills the power to the compressor and your fan shut off.

And sometimes, if you do that enough, it will permanently turn off after about three or four attempts, and set a code for over amping telling you the compressor is drying too many amps because it’s locked up