Ok, Ok, Ok, I butchered the vacuum explanation, I surrender.
Major edit to reduce the vacuum rage:)
I had a very intermittent/random “A/C not blowing cold” problem that progressively became worse over a ~6 month period;
When the A/C worked, it was ~40 degrees out the vents. When you least expected it, and needed it, you’d get no cold air.
Solution: Replace the engine intake air filter.
Background on the A/C system:
The 2010 does not have a traditional A/C relay setup, it has a “smart” computer (aka. A/C amplifier) dedicated to the A/C system. It’s buried in the dashboard, so pray it’s not faulty:)
That A/C computer has multiple sensor inputs; using that data it turns the A/C clutch on and off by providing a ground through the board. You’re going to find this hard to believe, but your intermittent A/C may be a dirty air intake filter.
Here’s why:
(Edited to reduce it to layman’s terms as I butchered the technical explanation)
For technical reasons I’ll leave to others, a clogged air filter tricks the A/C computer into shutting off the A/C clutch thinking it’s providing you more power in an acceleration situation.
Changing the air filter fixed the problem for me; how did I figure this out? Totally random. It was time to change the air filter, I removed it, held it to the sun and could barely see any light; held the new one up and the sun blazed through. I was shocked it was so plugged, then I remembered 2023 was very dry and lots of construction was putting insane amounts of dirt in the air.
I hope this helps anyone struggling with an “unfixable/random” Camry A/C issue! Oh, check your cabin filter behind the glove box too!
Another Edit. My Camry has an “A/C amplifier”, computer, that controls the A/C and will shut it off if it “thinks” you’re mashing the pedal.
You can read more about this here: A/C Amplifier HELP! | Tacoma World
Also, a Toyota dealer was stumped, could not see any issues, suggested waiting for total failure. Replaced air filter, problem solved.
