westside807

The other day it was around 100 degrees and my ac was blowing around 60+ degrees from the vent at idle and around 58 degrees driving. Today it was about 83 degrees outside and the temperature from the vents was around 44 degrees driving, so nice. I planned to have my ac system looked over after the 100 degree day, but now I'm thinking maybe my engine cooling system is not up to par.
Could my radiator or something else be holding back my ac performance? I posted a link of the type of radiator I have. http://www.radiatorexpress.com/produ...FZQ0aQodkvUOCg
So to be clear I'm wondering since my car cooled really well when it was 83 degrees and not good when it was 100 degrees what does that mean? The temp gauge says either 185 or 190 degrees, but I think a little higher on the 100 degree day. Not sure what kind of thermostat but no more than 190 degrees. I have a 1971 cutlass with the original 350 rocket that's been bored .030
Thanks for your input

Fun71

The first thing I would do is look at the sight glass on the receiver/drier to see if there any bubbles. Bubbles would indicate a low refrigerant charge, so it could be all you need is a bit more refrigerant.

westside807

I've been playing with the amount of refrigerant I have in it trying to get it right. It'll be cold then the next week it'll be cool. But am I fooling myself if I want the same temp coming from my vents no matter the outside temp?

MDchanic

Yes, you are. Whichever word you actually meant to type.


You don't mention year, model, whether original or aftermarket A/C, and R12 or R 134, the exact temperature, the relative humidity, or where you live, but the 1970 CSM shows that for an ambient temperature of 100°F, with a relative humidity of 90%, the RH outlet temperature should be 85°F at 2,000 RPM.
At a RH of 50% it should be 66.5°, and at a temperature of 110* and an RH of 20% it should be 62°.

- Eric

westside807

Darn auto correct, I meant "am I fooling..."
But it's R-134 conversion. New compressor, poa bypass, drier, expansion valve. The evaporator, hoses, and condenser are still R12. I live in Oklahoma, so it's hot, and we have heat and humidity. I thought I mentioned 1971 cutlass, if not I apologize.
So based on your information my system is working as good as it will get? I've read where some are getting good temps from the vents and I assumed they were in the hottest temperatures and every time they were in the car, silly me.

MDchanic

I figured it was something like that.



Yeah, look at the chart in the CSM - you'll see that performance is VERY dependent on humidity, so it is very important to record the humidity when you test performance.

On a very humid day, you will not get very cold outlet temperatures, which is why all manufacturers provide a "Recirc" setting, so that the moisture can be drained from the cabin, and the vent temps can go down.

- Eric

westside807

Yeah, look at the chart in the CSM - you'll see that performance is VERY dependent on humidity, so it is very important to record the humidity when you test performance.

On a very humid day, you will not get very cold outlet temperatures, which is why all manufacturers provide a "Recirc" setting, so that the moisture can be drained from the cabin, and the vent temps can go down.

- Eric[/QUOTE]
Thanks, so since my Cutlass don't have a recirculation feature the only option I have is to tent the windows and block all infrared!!! I like to be cold. My car is a 4 door family cruiser, and I like to freeze them out, lol. I'm so used to driving late model cars where even I have to turn down the ac. So is there nothing I can do? Would it make sense to consider vintage air who's system recirculates, or no?
Next year my daughter will be a senior in highschool and she lives in Georgia. I told her I'll drive the Cutlass to Atlanta to take to school on the first day(she spends her summers in Oklahoma, and thinks my car is cool). I'd love to have vent temps constantly around 40 degrees. I suppose I'm dreaming. Btw 60 degrees is better than 100 degrees, so I'm thankful for what I do have.

MDchanic

Why doesn't your car have a Recirc setting?

Has it been disconnected or partially disassembled?

- Eric

westside807

I've never seen it so I assumed I didn't have it. Should it say recirculate or is it called something else? My daily driver has a fresh air and recirculate button. I'm ignorant to that feature on my Cutlass. Teach me!!!

westside807

Ok never mind. I looked it up. Max ac is recirculate. I feel enlightened i never knew that!!!

jaunty75

Not a damn thing. Air conditioning systems don't put out a specific air temperature. They put out a specific air temperature difference. What the vents put out at 100F will be different than what is put out at 90F or 80F, and in all cases the A/C system is working fine.

It's not low temperature that makes you feel cool on a hot day. It is low humidity. If the outside temperature is 100F, you can feel downright cold if you're sitting in 80 F temperature and low humidity. It doesn't have to be 44F in the car to feel cold. The A/C system's job is to remove moisture from the air as much as it is to cool it.

You are making much ado about nothing here. You do not have an air-conditioning problem, and you do not have a cooling system problem.

MDchanic

When all else fails... Read the instructions!


Just jokin', but, really, a huge number of questions can be answered by reading the Owners' Manual or the Chassis Service Manual, which a huge number of people don't have and have never seen. I make it a point to read the Owners Manual and thumb through every page of the service manual of every new old car that I get (I will admit I am less diligent with newer cars, where the manuals are essentially a collection of warning notices).

Maybe that's why I annoy my wife so much when I drive with her - I've read her car's manual, and I know what the HVAC controls do, and I change the settings to suit the conditions, instead of winging it between OFF and MAX repeatedly, which is what she does.



- Eric

jaunty75

Remember something else. There is no such thing as 100% recirculate. No manufacturer would do that for safety reasons. You don't want the same air accumulating in the car.

Think 80/20 and 20/80. In normal mode, typical A/C systems recirculate about 20% inside with about 80% incoming fresh air. In recirc or max mode, systems recirculate about 80% inside with about 20% outside air. No matter what the setting, there is always some outside air coming into the car.

AzMotorhead

I didnt read all the responses, but youre getting a 40* drop from ambient temps which is about all you'll get. Its actually pretty good on a 100* day

banny

Id change that factory tube and fin condenser to a parallel flow unit. Classic Auto Air has them

westside807

Thanks for the information guys! I was just trying to find a way to make inside my cabin cooler. I'll guess I'll tint my windows.

MDchanic

Jaunty is correct, of course - in the event of uncontrolled flatulence, the potential devastation that could occur is far too hideous to ponder.

- Eric

westside807

Lol to funny!!