Can you recharge ac by yourself or not?

The majority of my redos for customers who have did it themselves or had a garage do their AC without the right equipment. I simply drain it completely 100% throw it on the vacuum pump get it down to roughly 500 µm. And simply fill it up by weight and that works 100% of the time all the time for the last 42 years of my life since I started with my father at 12 years old and that’s how he did it to. But we had the advantage with R12 we could top off refrigerant using the old school method because we had majority of fans on cars or fixed speed not thermal fluid collection in the old days you had slow rotating giant iron compressors that way 32 pounds fixed speed and displacement and you only had one engine fan no two Fan configurations that would turn off and on throwing your high side pressure and low side pressure readings off no variable flow condenser fans that would slow down to speed up and raise the speed that would change your low side pressure in your high side pressure and you’re constantly trying to chase and compensate something you can’t possibly imagine.

That’s why the guys who have been doing air-conditioning for 10, 20, 30 years Still try to apply the old method to new vehicles those are the guys you don’t want to listen to their information. Seems like some of the old-timers do more damage than the beginner do it yourself customers.

 

I’m guessing your windows did not look like this after the AC recharge in this video

 

If you were getting 53°F out your dash on a 93° day that was very very good.

On your Prius if you were only five or 6 ounces low on a 93° day your compressor would be spinning at 6000 RPMs all the time nonstop and your HP battery will be draining all the time and your engine would be idling all the time trying to charge the high-voltage battery.

Think of it as a bucket with a hole in the bottom and you’re filling it up with a garden hose think of the water as your gasoline and a hole in the bottom is the power needed to keep the compressor spinning at 6000 RPMs drinking the gasoline to charge the high-voltage battery.

Now with 100% completely full refrigerant charge the compressor does not have to work so hard and spin so fast all the time and draw so much wattage from the high voltage battery it still uses it but a lot less.

 

I get 25 degrees out of my center vent in 90+ degree heat with 80+ humidity.
According to the Toyota service records, the a/c system has never been serviced.
The previous owner has EVERY record of all the service he had done. It's a novel!
But good records. Yesterday, I turned 209,000 miles.

 

25°F ?
the ac-temperature is below freezing temperature?

 

I think you need a new thermometer.
Unless you mean 25 C.
At 25 F, your evaporator would freeze over pretty quickly.

 

Robinaire, two different ones.
And it won't/doesn't freeze. Once it's cold enough the cabin, it adjusts to a higher temperature.
And/or the ETR will cut the compressor out.
50˚ won't cool down very well, it will take a long time.

 

I've got no grounds to doubt that you've read the number "25" on two different thermometers, but I really, really don't think you had 25°F air coming out of a car air conditioner.

 

Oh well....
I "read" "25" because that is where the needle was pointing.
Indicating the temperature.
That's how it work.

When I worked at Mercedes we'd get 20˚. My 1990 Probe would get down to 20˚ also.
My 2002 Town & Country went to 18˚. Other cars I've worked on do the same.

It doesn't stay there because the compressor will kick off.
Put the setting to the coldest setting, fan speed on high.
When the inside of the car starts getting cooler, lower the fan speed.
As it gets to your desire comfort level, lower the fan speed to the slowest speed.
If you leave it on recirculate, and are driving the temp will go way down.
If you leave it like that, and it's humid enough, the evaporator will start to ice up,
because you have cold air blowing over a wet evaporator with freezing freon going through it.
That air will become freezing air.

In MY Prius, if I have it on AUTO with the temp set to 74-72, the fan will eventually go to the
2nd lowest speed, and eventually will go to the "fresh air" setting so hotter air blows over the
evap to keep it from freezing up, or thaw it out. Since I can see inside, nor care too,
I'm not 100% sure what's happening. I know when it does because I can feel it.
If I leave it alone, 1 or 2 minutes later it goes back to auto. I usually put it back on recirculate
and turn the blower to a medium speed for a while.
All of this is depending on the outside temp, and humidity, and if it sunny, cloudy, or night time.
Usually it varies between 32˚ and 45˚.

This may not be the EXACT way to explain it, but it's the best and easiest for me to explain it.
And there may be some grammatical errors, I'm just too lazy to go back and try to correct them.

And remember: "Results may vary"

My first novel!

 

Soooooo....
According to that table, If it's 70˚F, or 115˚F, ambient air temperature,
There will be no air temperature out the center vent, or low
or high pressure on the gauges?

 

Relax, I'm not trying to bust yer balls over grammar... but close. The units you use to report data are pretty darn important here.

When you report the ambient temp as "90+ degree heat" you obviously mean 90° Fahrenheit. Yet the report of the air temp you read out of the vent, "25" (or "20" for the Mercedes) can only be true in degrees Celsius.

The chart helpfully posted by @StarCaller isn't specific to a Prius, but it is a fairly useful generic automotive air conditioning table. If you are getting 25° Celsius air out of your vent on a 90+° Fahrenheit day, then your system is slightly underperforming the generic average in StarCaller's table- completely understandable for a 10 year old car.

If you were to stick to Fahrenheit throughout, it might read "77 degrees at the vent in 90+ degree ambient heat" which is quite fair to expect a car to do.

 

A 30 degree F drop across an evaporator core is considered really good.....no matter what the cooling system being measured.

I think he really BELIEVES what he is saying though and can't imagine what the communication problem here is.

 

I am relaxed, I don't care or worry about minor grammar errors. UNLESS there 50% of the
novel is in error and you can't figure out what the person is trying to say.

Since I'm in America, it's standard to use Fahrenheit. Other countries use celsius.
And yes, I know there are people who post here from other countries, and the grammar is not
always the best. But they have a good reason for it. Things get lost in translation.

I believe what I'm typing, because it's true. I've experience it since the mid 1980's.

If you didn't have some type of device to tell the compressor to shut off when the evaporator
got "too" cold, it would freeze eventually freeze up unless only warmer air passed over the evaporator.

 

Yes and I have some beachfront property to sell you in Arizona. Wait that’s not all if you act today and respond within 10 minutes I’ll throw in the Eiffel Tower. That Toyota technician was a superman

 

Grammar errors are my middle name. Something about voice to text with my iPhone and Prius chat website and one other website give me horrible grammar errors and even double and triple sentences get printed down.

As long as temperatures are not being taken using an infrared thermometer that is the absolute worst way you can take a duct Dash temperature.

I converted my old 90s town car from an orifice tube system to a expansion valve system did a few modifications overrode the safeties for the compressor. Get it down to 13 Fahrenheit and yes the evaporator would start icing.Get it down to 13 Fahrenheit and yes the evaporator would start icing I had a manual override switch to let the car safety switches take over when I would feel the ice build up so much my evaporator started turning into a block. I would just use that feature on the hottest days for instant quick cool down no regards to the safety for the compressor. But then again I did some elaborate extra stuff with fans and airflow and insulating lines

 

Do you have Techstream available? What would be super interesting to see would be the evaporator temperature read by Techstream (there's a thermistor right on the coil) and the evaporator target temperature, at the same time that your Robinair thermometer is telling you 25.

The other day when I was testing the system in my 2010, the target evap temperature chosen by the ECU was 35℉, when set for max cooling. That seems a reasonable target, to cool about as well as possible without beginning to ice the coil, which would end up restricting airflow and not helping.

I would be curious to see what target evap temperature your ECU is shooting for. And if it is shooting for 35℉ like mine does, the next question would be how come it can't help undershooting its target by ten degrees, when it has full control of a variable-speed compressor and there's also a TXV?

 

Exactly back it up with TechStream right at the sensor.
The big fish tales that got away.

Sounds like the same kind of math use by Bernie Madeoff and Emron corporation. Cooking the books there with those numbers.