Weak A/C when it is hot

there are twofers in front of the radiator, iirc.

 

Well, that stinks. I once had to take an Intrepid back about about a half dozen times for AC repair. I had it in a nearby independent shop. I was working a temporary job in California and coming home every other weekend. Four trips in a row, I would fly home and the AC would quit on my first or second drive. Take it back, drop it off, and go back to CA. It was like Groundhog Day. Finally, I took it to the Dodge dealer and made the independent shop pay for it. (The indie shop balked, but I suggested that neither of us wanted the complications of third party involvement. They took the hint.) Next trip home, it quit again. Dodge finally got it right on the second try.

 

I guess I will have to make a video just for Priuschat just on (HOW TO TEST YOUR A/C WITH OUT GAUGES).
If you have some refrigerant in your system 90g., 150g., 250g. that will be more then enough to run the compressor. Even if you only have 1 drop of liquid refrigerant in your refrigerant system that is WAY MORE!!! then enough to produce the pressure to close the low pressure switch and engage the compressor at first.

Lets say we are vary low at 250g. the morning is a nice cool 57F you turn on your A/C but you will need some sort of temperature measuring device, long probe to fit down the vents preferably.
lets say you do not have experience with experience compressors, with all the other noises you can not tell if it is running. (no clutch LOL)
1: With the A/C on with 250g. and 57F anbient temp. you may have 47F even 43f out your dash. Later on in the day say around 75F 78F you may have 70f to 72F almost so little you are not sure its working. But in the morning it droped 10F to 14F something happened for sure.

2: If you took you hand in that morning you would feel the suction line (big pipe) leaving the evaporator feels about 37F if but later that day if you touched the same pipe in the same place it would feel 65F for example maybe a little more or less. too close to tell using your hand. (except with lots of experience " temperature calibrated fingers").

3: Now with the a/c running if it is. ( only a experienced person "WARING MAY LOSE FINGERS"!!) FAN MAY START AT ANY TIME.
You reach down and touch the suction line entering the compressor it mat be 70+F may have picked up some hot warn engine heat slightly warming the suction line. Now reach over and touch the discharge line leaving the compressor. If it has been running for some time ( BE CAREFUL IT MAY BE BURNING HOT TO UNCOMFORTABLE HOT!). Then this means the compressor is running.

Now the reason the compressor is so hot is because the compressor is starving for oil and cool refrigerant return. A over charged a/c with refrigerant can give you a burning hot discharge line too???

OMG for the people who know about using a P/T (pressure temperature chart) how can I get the same hot high temperature with both low pressure and high pressure???. ( this is for the guys who re-charge by pressure or temp). or sight glass LOL.

Also there is a point were the refrigerant level is low just at the right point were the pressure is much higher then then when it is 100% correctly filled. As if was over filled, restriction, fan not working or too slow, over heating radiator, hot water flowing in the heater core and hot air mixing with cold air putting a load on the evaporator at the same time. All these that can give the sane test data symptoms. That's just the top of the list not every thing.

Not to mention all the shops and DIY who DO NOT own a refrigerant analyzer and recover contaminated refrigerant. Mix it with all their recovered gas then put it your car like a STD. Then there is the guy who uses shop air to pressurize the a/c system to test for leaks. You may as well pour water in the a/c compressor, same thing. The shops that do not change the filter drier on the recycle
machine a lot of moisture contamination. Shop that use old RRR ( refrigerant recycle machine) that only has a weight scale accuracy of +- 60g to 90g ( 2oz to 3oz) when they were brand new lets not even talk about after 5 ot 10 years. On a Prius with a charge of 420g add 3 oz and see what happens or remove 3oz and you get what happen happen to this car of ( PASADENA_COMMUT)
Just a little leak just a little low because a leaking EVAP. We hope that all.

OH YEA Just 90g (3oz) over charged or 3oz low refrigerant charge and the Prius GPM takes a nose dive. (tell me why ???...

 

Precision. Get exactly the right amount of refrigerant in there and the compressor can stay in its comfort zone.

Get it wrong and the pump is either fighting too hard vs. overpressure or it is running much longer to build up to normal pressure. Either way wastes a lot of power, and burning more gas is the only way the system can make up that loss.

 

It's good to run AC regularly, say at least weekly for 5~10 minutes. Using the heat/defog vent mode may also run AC, even if the AC button is not lit. Not using it for protracted time, the seals may dry out from lack of the internal oil circulating.

 

Bingo you just won the $64,000 question.
You would be amazed at how many mechanical shops I go into and they’re trying to figure out why the Prius is getting bad gas mileage and the engine keeps idling constantly often on when the air conditioning is on.
Often many spark plugs get change ignition coils get changed anything to do with the engine or airflow or gas flow components taking wild guesses at changing parts to cure the problem.
When all it was was 3 ounces of refrigerant in either direction.
See what happens with the guys with the little cans to fill by pressure or temperature they believe they’re doing their customer a honest service.
Yes air conditioning on a Prius can greatly affect your gas mileage” When it’s in properly charged!”. But when properly charged it just coast and idols along with no effort not drawing a lot of amperage from the HV battery.

 

Actually that was in is true for the old-style mechanical compressors that have a external shaft seal connected to a external clutch.
Like the old York and company and general motors or Frigidaire axial six compressors are the most famous for having the front shaft seal that is actually oil pressure Feed to keep it lubricated.
But now we’re talking about completely sealed compressors with no external protrusions relying on a lip style seal.
The seals at hose fittings we do not have to worry about when they decide to fail they’re going to fail not due to use or lack of use.