A/C answers

[wwest]

Late back in the last century, late 80's, automotive A/C engineers began working on the issue of alleviating the various discomforts of automotive A/C, TOO COLD airflow, blower noise, etc. The 1990 Lexus LS400 is a showcase for just how successful they were.

 

Many of the features they used have now been adopted pretty much across the board for automatic climate control systems.

 

There is no longer a rapid cooldown, automatic MAX A/C mode, for quick cabin cooldown after setting out closed up in the sun on a HOT day.

 

For a rapid cooldown you MUST put the system in MAX cooling mode and HIGH blower speed MANUALLY, put the system in FRESH, manual over-ride, and lower the rear windows slightly. It remains a mystery to me as to why the majority of these modern systems automatically switch, initially switch, into RECIRCULATE in this situation. Then advising the driver that a quicker cooldown can be more readily attained by lowering the rear windows.....??

 

Stupid, UTTERLY STUPID...!!

 

Once the HOT cabin atmosphere is exhausted, a matter of just a few moments, roll the windows up, NOW put the system in recirculate, and lower the blower speed to your sound comfort level, lower is now BETTER. The longer the air takes to flow through the cooling evaporator the more it will be cooled.

 

Having the system in MAX cooling will bypass the REHEAT/REMIX cooled airflow mode and you might now begin to be discomforted by the COLDNESS of the system airflow. But I would suggest leaving the system in MAX cooling until most of the interior surfaces, the remaining sources of RADIANT heating of/to your body, are also cooled to a more comfortable level.

 

I have modifications to ALL of my cars such that the A/C compressor clutch circuit can be opened throughout the winter months and a water flow shutoff valve so that hot water flow to the heater core can be blocked during the times the A/C might be of use for cooling purposes.

 

Slight improvement in FE also results as the A/C system's efficiency is improved significantly.

Edited June 24, 2009 by wwest

[igcitng]

I really appreciate your post. It has been 99 degrees and SUPER humid here for three days now and my Edge just does not cool off after sitting in the sunny parking lot all day, even after driving 30-45 minutes.

 

I do open the windows to let the hot air out, and put it on MAX for a short time. I was afraid to leave it on MAX and have the fan on high because I did not want to stress the system in the awful heat.

[akirby]

Turn the auto hvac down to 60 degrees, roll down the windows for a couple of minutes, then roll them back up. You don't need to do anything else. You don't need to rewire your compressor or replumb the heater lines.

 

Slowing down the fan so the air spends more time moving through the coils is ridiculous. Put it on high and forget it.

[resq330]

Turn the auto hvac down to 60 degrees, roll down the windows for a couple of minutes, then roll them back up. You don't need to do anything else. You don't need to rewire your compressor or replumb the heater lines.

 

Slowing down the fan so the air spends more time moving through the coils is ridiculous. Put it on high and forget it.

 

 

 

Some of us don't have the luxury of Automatic Climate Control.

[igcitng]

Edge's come with climate control? Did not know that. Wonder what else I am missing.

 

I tried what you said and it made for a much more comfortable ride home. Not as cool as I would like, but 99 degrees and humid is hard to fight. Unusual weather for us.

 

Thanks again.

 

 

Some of us don't have the luxury of Automatic Climate Control.

[Waldo]

The longer the air takes to flow through the cooling evaporator the more it will be cooled.

 

It's true that the air will be colder, but you will have less of it coming out, so the net effect in the cabin will not necesarily be a colder temperature. I could put one ice cube in my drink and leave it in there until it melts, or I can put 10 ice cubes in there and take them out after 5 minutes. Which one will give me a colder drink after 10 minutes?

 

I have modifications to ALL of my cars such that the A/C compressor clutch circuit can be opened throughout the winter months and a water flow shutoff valve so that hot water flow to the heater core can be blocked during the times the A/C might be of use for cooling purposes.

 

Not quite sure I understand the point here. You don't want to run the compressor in the winter, so you rigged up a switch that does the same thing as the A/C button? Using the compressor in the winter keeps the humidity down and keeps the windows from fogging up. Are you suggesting people should drive around with fogged windows?

The heater core has a door over it. When the climate system is trying to cool the car, the door is closed, so the cool air does not pass through the heater core. I guess it's true that the door itself would heat up a bit with the hot water passing through the core, but limiting the flow of coolant would increase the chances of your engine overheating.

[akirby]

Some of us don't have the luxury of Automatic Climate Control.

 

Same principle - put the fan on high and the temp control on max cold.