Automotive Air Conditioning Information Forum

Indeed.

Old timers here called it drive-off. End of the day, 3:30 pm. Car has been in the sun all day. Crank it to max air, and drive. Head pressures at their worst.

That is why I want to see the full charge in an unknown system, then a full load test. If it goes beyond reasonable pressures, or starts to cycle on the HPCO, yeah shut it down. Otherwise run it for at least 90 seconds to stabilize at worst case. THEN decide what may need work.

And, we have seen the reverse in here. Someone finds that chart on a car forum someplace, and decides that their high side is too low because the chart says 325 psi. So they grab the can with a gauge...

Lots of variables on an MVAC system. People start sweating and want fast results. Sometimes it goes wrong.

bohica2xo wrote: ↑Tue Jun 14, 2022 8:16 am Someone finds that chart on a car forum someplace, and decides that their high side is too low because the chart says 325 psi. So they grab the can with a gauge...

Lots of variables on an MVAC system. People start sweating and want fast results. Sometimes it goes wrong.

But the gauge was still in the green!

HAHAHA

Been some winners over the years. Remember the guy that put in a radiator half as wide as the OEM to make room for the intercooler - and then blamed the A/C condenser for the engine overheating?

Brad, when google choppers keep calling with a dozen questions. My response, sure that will work. Heck, what do people expect for free these days?

hi
What people forget , any really experienced refrigeration mechanic absolutely HATE automotive . WHY because the systems are a complete compromise and 80% of them are built to a price .--
---So what is wrong
the condenser side
,,, is way way small has more to do with low hood lines and total cost to vehicle maker ie small condenser =more profit
,,, refrigeration and aircon that used R12 runs at 130--150psi..SO WHY DO WE SEE THE HIGH PRESSURES ????
,,,r22 GAS RUNS AT 200--250 PSI ...r22 ALWAYS OPERATES AT HIGHER PRESSURES THAN r12

R12 at 130 psi = R134a 150psi [temperature is the same R12/R134a ]

The ambient x2 x3 rule is exactly that a rule of thumb . In commercial HVAC the SEER rating typically varies condenser size so any rule of thumb DOES NOT WORK . A refrigerant has the lowest high side psi it can run for max efficiency .

So R134 run thru a condenser should be 150--200psi under all conditions if the heat exchanger is big enough ,which in a car they are not .
A car /truck etc running 150psi WILL in 110--125 f ambient will give outstanding vent performance.

+++++++All the refrigeration TECHNICAL charts show R134a in an A/c SYSTEM is running at MAX efficiency at 150psi . THIS IS SCIENTIFIC PROOF ..FACT

Just trying to demonstrate to people how a great system operates . Most Automotive is a real compromise .

Then there is the low side , another time ...

Okay.

hi
Not trying to force this onto people but like my trade school taught me ,learn the theory /actual correct spec of a good example and everything else is easy .

And yes working in automotive is always a compromise .
MY passion for auto a/con was started along time ago , I then did repair work in the middle of a desert [dry and very hot ], then underground mining [very humid and hot ] , then moved into the tropics . Air cons work hard in all these conditions .
Yes I`m very passionate ..

R22?
(Laughs in 410a)