2008 TL, 90k miles, started Noticing noise under hood in sync with engine, only louder. Took it to Acura, after listening to it, they said if its just a noise don't worry, possibly just something loose (I.e alternator bolt?) and keep an eye/ear on it ($0 invested). Shortly after, went on a 3 hour drive, noticed the A/C worked fine for an hour or so, but then started blowing warm air. Took it to another shop, they said replace the whole A/C system ( new compressor etc), $1300 which i declined (not going back there). Took it back to acura since thought both noise an AC issues were related, (and after doing some forum reading) they replaced the A/C relay ($8 part, $100 labor) so the noise isnt as bad now, and noise goes away when I turn the A/C off. So the noise problem is diagnosed and fixed to my satisfaction, the compressor goes off when AC is off now that relay switch was replaced.

However, the AC still only works for the first hour or so on long drives (which I make 2-3 times a month) then it blows warm air. While on the long trip, if I turn AC off for 20-30 minutes after it starts blowing warm, it will blow cold again for another hour or so. I looked through other posts, couldn't find similar problem, and I dont know much about how to fix AC issues. I dont want to spend $1300 if this problem could be fixed relatively cheap and easily. Any help would be appreciated!!

 

I had this very problem in a Ford truck...work for about an hour and then blow hot air. Turns out the problem was a broken wire that went to the A/C compressor clutch...the copper wire in side the insulation was broken and would separate when the engine compartment would get really hot. Took a lot of work to find the broken wire.

suggest that when your A/C stops, check to see if the compressor clutch has stopped spinning. If the clutch has stopped spinning then you have an electrical issue that is dropping power to the clutch coil.

 

Also have the refrigerant level checked. If its too low the compressor could run for a while then shut off. and if it's overcharged the condenser and other parts can freeze up causing the a/c to not work.

 

It could be the field coil, I had this happen last year to me, $100 part and something you can do yourself if you're comfortable working on your car:

https://acurazine.com/forums/3g-tl-problems-fixes-114/c-field-coil-replacement-guide-772614/

Basically as the A/C system and clutch heats up, the coil fails to provide enough magnetism to actually engage the clutch for compressor and thus warm air instead of cool

 

Thanks for the advice thus far. I've been paying closer attention to AC functionality the last couple days, and I don't think it's performing properly, even at start up.

When I start the car, and turn the AC on Lo on the highest fan setting, it's definitely not blowing as cold as it should, and the two passenger vents are barely cold at all (warm in fact). This is in addition to after an hour of running, the AC blows nothing but warm air out of all vents.

Does this description point to a potentially different problem?

Thanks