Tofer

I have a 94 4Runner SR5 with the 3.0L V6, The AC has worked fine up until just recently when I would go on long drives, usually over 2 hours of continuous driving, the air would slowly become hot, to the point of it was cooler to just have the vent on then to have the AC blowing. This has happened to me 3-4 times, but because in town driving was fine, it blew cold all the time, I wasn’t TOO concerned about it, that was until this weekend when it started to do its “cooler on vent then AC skit” after only 30 mins of driving... figuring it was the coolant level, I went to the auto part store and bought a refill kit, took it out hooked it up and the pressure was fine, the needle went to 45, the max for the 134a coolant, and now the AC doesn’t work even in town... there is plenty of Freon, but no cold air.... its in the upper 90s and its only going to get hotter from here, and I would REALLY like some AC..... any suggestions on where to start?

jimbo74

freon on r134a? freon is r12 which is the older stuff
r12 is not compatible with r134a, unless the system was converted.....

Tofer

I believe the system has been converted, there is a R134a sticker next to the hood latch, talking about pressures ect.

HondaTec521

Is the compressor even turning on when its blowing warm ? You really need to check both hi and low side pressures to get an idea of what the system is doing.I'd recommend taking it to a shop to have it checked out.

CMD93

1994 and up 4runners have the new freon.

Highland Runner

Go out start your Runner, open the hood and turn the AC on. Is the compressor turning/cycling? Is the small electric fan coming on at the same time? If these are working, look at the sight glass on top of the dryer. This is located on the right side and in front of the radiator (looking into the engine). Are there bubbles in it? The 134 could still be low even though there is pressure in it on the low side. Get a Chiltons or eqivalent book for your Runner. It has a section on AC troubleshooting. I think there is also Chiltons just on AC.

Tofer

UPDATE: today when i went out and started up my 4runner, turnd the AC on max and sure as ˟˟˟˟, it was ice cold... any reason why it would not work one day and then be cold the next?

rpeAMP

Evacuate some of the freon. When it gets hot outside (and inside the engine compartment), the pressure increases internally and in your case (because you're at the threshold of being overfilled), causing the high pressure A/C sensor to kick the compressor off intermittently.

Let it down to about 30-35 PSI and report back. You can do this by sticking a thin screw driver into the low-pressure side cap and pushing down the valve inside. Be careful that your face is away from the direct upstream path of that valve. I realize this is technically illegal, but he's draining just a few PSI and will save him money and time of getting the entire system diagnosed and "repaired".