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A/C Sometimes Blows Cold, Sometimes Not

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Old 07-13-2012, 09:46 AM
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I always thought my a/c wasn't cold enough, but after reading this thread I think I might be experiencing the same thing as everyone else here; I thought perhaps my refrigerant was leaking out slowly since I only use the a/c when it's super hot outside (or it's raining and the glass starts to fog up).
Old 07-13-2012, 10:55 AM
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Originally Posted by xviper
Do any of you have an actual coolant temp gauge to confirm what I'm about to say?
On a recent roadtrip through Zion Park, Bryce Canyon, Grand Canyon and Death Valley, a couple of S2000s noticed an interesting trait. Mine is an AP1 and the other was an AP2. Both of us remarked that there were times when the A/C would stop blowing cold air and just blew unconditioned air from the outside (which was quite hot ~104). When the engine was subjected to unusual load such as going up an incline and lower road speed, my engine coolant temp went up to about 237*F. This is also about when an AP1 hits "4 bars". I don't how many bars an AP2 would be at this temp. Compound this with lower road speeds that reduced the amount of air going through the rad and this aggravated the high coolant temps. Once we got back up to higher road speeds, this situation never occurred as the coolant temps came back down to a more reasonable level.
This is when the A/C stopped working. I believe it's a sort of built in failsafe where the ECU tells the A/C compressor to de-clutch so as to remove a bit of load from the engine at a time when it's laboring the most. During these hot conditions, the rad never blew and the engine never "over-heated" as such even though it was running extremely hot.
My car did it the most as I've got a FMIC sitting in front of the engine rad.
Very interesting. Nice to know the car prioritizes for you. My mother's 97 Accord did not do this; when I got caught in apocalyptic stop and go traffic on the Garden State Parkway in 95*F weather with the AC on, the car did overheat, but not enough to cause real damage before I noticed.

I've never seen my AP1 go above 3 bars, and I've driven on the highway at 107*F days and autocrossed on 95*F days. I'll bet neither of those would get the engine as hot as going up a continuous hill at 104*F though.
Old 07-13-2012, 11:40 AM
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I don't know of any car that automatically reduces its load to keep the engine cool.
Old 07-13-2012, 12:50 PM
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Thanks for the suggestions Saki. I very rarely floor the car, especially with the AC on, so this is not when I am experiencing the warm air. The AC does work better on milder temperature days, but I sometimes feel warm air coming through even though the temperature is at max cold.

Regarding the refrigerant, how would I know if my system needs to be topped off?
Old 07-13-2012, 02:30 PM
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Originally Posted by J-Speed Inc.
Thanks for the suggestions Saki. I very rarely floor the car, especially with the AC on, so this is not when I am experiencing the warm air. The AC does work better on milder temperature days, but I sometimes feel warm air coming through even though the temperature is at max cold.

Regarding the refrigerant, how would I know if my system needs to be topped off?
PSI check while running at 1500rpm
Old 07-13-2012, 06:17 PM
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OK, what pressure should I be looking for?
Old 07-14-2012, 07:47 AM
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Originally Posted by J-Speed Inc.
OK, what pressure should I be looking for?
There's a chart based on outside temp. Someone should have it in jpg. I don't unfortunately.
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