What Kills Prius Compressors ? How to prevent it !

What kills a Prius compressor is really simple to prevent. Heat!. What kills transmission fluid? Heat !. What kills an engine ? Heat !. So will lack of lubricant.

As your refrigerant level gradually and slowly gets lower. So does the return of refrigerant oil and so does the return of a cool supply of refrigerant over the electric motor windings that gets very very hot. Some of the Prius compressors later models put the inverter on the top of the compressor which gets very hot on its own not even mentioning the heat from the windings of the motor. And they both rely on a cool fresh stream of ample refrigerant to return to cool them off to extend their life.

In the YouTube link below I show a Prius compressor and the temperature of the discharge line at 190°F plus. One thing most technicians don’t know whatever the temperature of the discharge line outside of the compressor the internal temperature at the point of compression on the surface of materials where the lubricant i’m bearing surfaces is between 50°F to 75°F higher than the external discharge temperature. Most refrigerant oil start breaking down at 230°F This is about first grade math I think you could see the picture that’s about to happen.

The static resting pressure on the gauges was 42 psi When I connected my gauges.when I connected my gauges. some people say the low pressure switch on a Prius will protect the system from running when it’s out of refrigerant.

At 42 psi with the ambient temperature around close to 60° that means there was absolutely no liquid refrigerant in the system it was just vapor left. But yet the system we’re still allowed to operate this is normal do not believe what others tell you about the low pressure switch cutting off the compressor when it’s low on refrigerant. This is normal.

You will also notice the high side pressure was 60 some odd psi plus with only 3 ounces roughly refrigerant in the entire system. I released a video about two days ago on a 2012 Prius C that I just recharge to factory specification of 420 g took it out on a road test with live Bluetooth sensors connected up to the pressure ports and temperature sensors on the refrigerant lines. Driving the Prius with the air conditioning on max position for fan speed as cold as possible and the high side pressure was only 66 psi and this was normal for this vehicle under these operating conditions.

I also immediately pulled over the vehicle after driving for a few minutes with the camera still running opened up the hood and showed you the site glass for the refrigerant was all bubbly and barely flowing the majority was air with very little liquid refrigerant but yet the day before I just filled it up with 420 g of refrigerant that is factory specification. Don’t believe the boys who believe in bubbles. They live in a bubble world full of rainbow ponies and unicorns.

 

Completely ignore all the pressures and temperatures and if you fill up exactly by Weight only everything will be perfectly OK. Absolutely cannot go wrong if the weight is correct

 

Your last paragraph answers all the questions.

there are so many variables to take into account this is the reason why so many people get it wrong even if they try or even attempt to use a chart for pressures or temperatures.

Most of the charts were developed back into years when we had fixed speed compressors not variable. Because the individuals who write the news articles magazine articles books and old technicians come from the old school days they keep attempting to try to use old-school methods on modern vehicles and they keep just re-printing all printed stuff because it’s simpler and easier.

The condenser temperature drop method that you’re talking about is for determining other things.
But the condenser sub cooling is for calculating refrigerant charge on a expansion valve system.
you use superheat method if it’s an orifice tube air conditioning system.
But on today’s cars with the variable compressors and variable condenser fans you can throw that out the window. You’ll be chasing movie numbers all the time the manufactures do not provide software that you can put a hard lockout you set the vehicle in a test mode where it would take over and manually set the engine speed or the electric compressor speed to a fixed speed that would not vary. Then set the evaporator to a fixed speed. And set the condenser fan to a fixed locked in speed. Then you can develop a pressure temperature chart that technicians can follow when the vehicle is put into this test mode that would be activated for testing only.

In Toyotas Techstream they do this they have a air conditioning test mode you can access to the software I have a video on this on my YouTube channel. Anybody who works on Toyota Prius knows this. Toyota software takes over controls all the system and air conditioning compressor speed the fan speeds it uses all the temperature and pressure sensors with their built in math algorithm software for figuring out whether the air-conditioning system is charged correctly or not.

 

You’re correct not on GEN two wasn’t thinking about that totally forgot.
I have my own clamp on Bluetooth temperature gauges I don’t need TechStream . And I have my hands my ears and my senses they actually work faster and better than Tech Stream.
Some of my coworkers who see me work on cars say I’m like one of the religious healing guys just lay my hand on the vehicle and it fixes itself or gives me the diagnosis without equipment. Hallelujah you’re healed

 

I grab the suction line before entering the compressor. On a hot day it’ll be nice chilly and cold with lots of condensation dripping off of it.

 

Hot day, all doors and window open, high fan, fresh air mode. Vehicle out in the sun



This dose not 100% mean there is enough charge but this is a good basic backyard mechanic indicator. Without getting technical and starting to use contact thermal couple temperature probes on refrigerant lines, using delta T method of evaporator temperature drop, Plus you’re high side and low side pressure’s, taking in account ambient temperature, If it’s a accumulator system taking the Delta temperature drop across the inlet and outlet of a accumulator. But most vehicles today we no longer have the easy opportunity of taking the Delta temperature drop across the evaporator because the expansion valves are off to located under the dash.

But when it comes down to it it’s so easy and fast to recover the refrigerant and recharge it by weight nothing else comes Close or even compares. A two minute to 5 minute recovery time in perfect conditions pulse 60 seconds to fully recharge system with refrigerant.

Why would I want to go through all that trouble of hooking up gauges and taking readings doing math unless I was looking for a problem. Or wanting to confirm that the system is working correctly.

In the 2 to 5 minutes it took to recover the refrigerant you will immediately know whether you’re full or you were Low or empty by Weight after that you can perform your diagnosis. It’s either yes or no.

 

If they are legitimate shop and they don’t have gauges they should not be touching AC PERIOD !!!..... now we’re gonna start using the word HACK ! and BUTCHER !. Starting to sound like the same kind of shop when the transmission burns out they get a new transmission or wrecking Yard transmission but don’t flush out the transmission cooler that has the metal flakes in it from the burnt one or the old torn converter and they put it on charge the customer and only last 30,000 miles and burns out again.

We are motor shop with no gauges those are the guys when they accidentally overfill it and it starts blowing out the refrigerant out the pop off valve on some vehicles releasing refrigerant to the atmosphere. When they need to change a part they don’t own equipment they just open up the line and bleed the refrigerant to the atmosphere. Those are not shops those are animals of a lower human species.

OK now I’ll come down and get back to the question.

Because the Prius has a electric compressor unlike most of the cars this is an added heat load.

There is a situation where when you have a lower charge at a certain point the pressures that were falling and going down start going back up again. It is a situation when your overcharge in the pressures go up again. And yes the more heat there is outside the more heat there will be in the system to dissipate through the condenser.

Trying to put one formula for all cars is not possible. Remember the vehicles with the fluid thermal fan clutch that fan clutch holds it calibration pretty well usually within the first 30,000 to 50,000 miles. After that it doesn’t work so well and you just starting to lower the airflow over the condenser this will mess with all your numbers and you will be off.
Then you’ll have guys who don’t understand the systems with fans that pulse the fans with a constantly moving target of pressure that’s bouncing up and down as a say for example the fan pulses on when the high side pressure hits 230 psi keep the fan on until the pressure on the high side falls to 150 psi turns off and repeats so fast that you can never use the pressures to determine what is right and what is wrong. Then you’ll have guys who don’t understand the systems with fans that pulse the fans with a constantly moving target of pressure that’s bouncing up and down as the sea for example the fan pulses on when the high side pressure hits 230 psi keeps the fan on until the pressure on the high side falls to 150 psi turns off and repeats so fast that you can never use the pressures to determine what is right and what is wrong.
Been vehicles with fluid driven fans remember the infinity with what looked like a power steering pump but actually drove the fan at different speeds this constantly moving your target temperature or pressure.
Then there are the two fans on the condenser we’re only one works until a certain pressure and then as your steadily lean out and it keeps raising then the second fan kicks in.
And there’s other variations so many other things that can affect your pressures and temperatures. Usually everybody just wants one way of doing things simple and short and then they apply it to everything and this is where all the mistakes start to happen. Human beings are naturally lazy and look for the easiest method.

That’s why it is nice that Toyota has their AC volume test under tech stream software. That’s only in the later versions of vehicles but since the majority of the mechanics at Toyota know nothing about air-conditioning they could just hit a volume test button and be in the ballpark as good. But it’s faster and easier to just drain the system fill it up charge the customer and make money and push it out the door. The guys at Toyota or on a bonus program the more cars they get done in a day and more billable hours the more money they make and then you have the s Service advisor on their little bonus their hand is in the piece of the pie. And there is a shop manager who is under pressure by the owner or higher ups to make the numbers profitable he gets his little bonus at the end of the quarter.

If you did only one vehicle one model one bike and you try to apply pressures and temperatures that never change yes then you can do this. You were able to be able to map and graft every ounce of refrigerant over a wide range of temperatures and come up with a pretty good fixed chart that you could apply to every vehicle of the same year the same make the same model under the same conditions.

Oh yeah I remember those guys don’t check the cabin air filter that throws your numbers off when they’re dirty even partially dirty.