With regard to A/C
It went downhill when in the 70's due to engines being strangled for power due to emissions controls, Detroit made the switch to cycling compressors.
Prior to that, the compressor ran all the time when A/C was selected. To regulate the temp of the evaporator both an expansion valve and an evaporator pressure regulator valve worked in tandem to keep the outlet air temp cold without icing up the evaporator. There was also a receiver/accumulator on the condenser side that held excess refrigerant (R12, the good stuff) and prevented it from flooding the compressor. It also had a sight glass so at a glance, you could discern if your system needed a charge.
Examples of these compressors were the renowned Airtemp RV2, the Frigidaire A6 wobble plate, and the York/Tecumseh used on Fords. Sadly, these workhorses were replaced with Sanden/Sankyo, Denso, and Hitachi units that while reliable, lack the gusto to really move the refrigerant. Some units in the larger GM B body cars as well as the "fuselage" Mopars had 3T of capacity believe it or not!
Another factor was the constant airflow going over a properly sized condenser. The fans back then were driven off the water pump and they were either direct drive or had a fan clutch. At any rate, when the engine was running, there was airflow across the condenser that brought the refrigerant back to a high pressure liquid state. One of the most common causes of poor A/C performance was and still is, a dirty condenser.
Of course, R12 while not Oh!zone friendly, worked much better at heat xfer than does R134a. And virtually all compressors cycle on and off apparently to save fuel. The result is a rather uneven temp from the A/C outlets. My current Corolla and prior Suzuki are by far and away the worst performers in this regard. In fact any temp above the mid 80's means I have to use the recirc function in the Corolla to keep the air even moderately cool. Put the thing in stop and go traffic, and performance really tanks. And yes, it is fully charged with refrigerant. That is the nature of the design. The compressor is slightly larger than a beer can and the evaporator core is about the size of a panel air filter. Not a whole lot to provide cooling. And the electric cooling fan pulls just enough air over the whole thing to keep the temp gauge in the normal. No more, no less.
The only vehicle I ever owned that had stellar A/C performance was a 75 Cordoba, sans Corinthian leather. It was a pimpmobile for sure. I even had dice hanging from the mirror. But let me tell you the Airtemp system was the best performing A/C ever. Same with my uncle's 73 Polara. No matter how hot or humid it was, you were comfortable in those cars.
I thought in the late 80's Mopar had a variable displacement compressor on their higher end cars? Not too sure on that one.
It went downhill when in the 70's due to engines being strangled for power due to emissions controls, Detroit made the switch to cycling compressors.
Prior to that, the compressor ran all the time when A/C was selected. To regulate the temp of the evaporator both an expansion valve and an evaporator pressure regulator valve worked in tandem to keep the outlet air temp cold without icing up the evaporator. There was also a receiver/accumulator on the condenser side that held excess refrigerant (R12, the good stuff) and prevented it from flooding the compressor. It also had a sight glass so at a glance, you could discern if your system needed a charge.
Examples of these compressors were the renowned Airtemp RV2, the Frigidaire A6 wobble plate, and the York/Tecumseh used on Fords. Sadly, these workhorses were replaced with Sanden/Sankyo, Denso, and Hitachi units that while reliable, lack the gusto to really move the refrigerant. Some units in the larger GM B body cars as well as the "fuselage" Mopars had 3T of capacity believe it or not!
Another factor was the constant airflow going over a properly sized condenser. The fans back then were driven off the water pump and they were either direct drive or had a fan clutch. At any rate, when the engine was running, there was airflow across the condenser that brought the refrigerant back to a high pressure liquid state. One of the most common causes of poor A/C performance was and still is, a dirty condenser.
Of course, R12 while not Oh!zone friendly, worked much better at heat xfer than does R134a. And virtually all compressors cycle on and off apparently to save fuel. The result is a rather uneven temp from the A/C outlets. My current Corolla and prior Suzuki are by far and away the worst performers in this regard. In fact any temp above the mid 80's means I have to use the recirc function in the Corolla to keep the air even moderately cool. Put the thing in stop and go traffic, and performance really tanks. And yes, it is fully charged with refrigerant. That is the nature of the design. The compressor is slightly larger than a beer can and the evaporator core is about the size of a panel air filter. Not a whole lot to provide cooling. And the electric cooling fan pulls just enough air over the whole thing to keep the temp gauge in the normal. No more, no less.
The only vehicle I ever owned that had stellar A/C performance was a 75 Cordoba, sans Corinthian leather. It was a pimpmobile for sure. I even had dice hanging from the mirror. But let me tell you the Airtemp system was the best performing A/C ever. Same with my uncle's 73 Polara. No matter how hot or humid it was, you were comfortable in those cars.
I thought in the late 80's Mopar had a variable displacement compressor on their higher end cars? Not too sure on that one.
