Fo by Fo

I have 91 4runner 3.0 5 speed. A year ago my ac clutch went bad, I put off fixing it, and I ended up ruining the compressor too. Long story short, I replaced the clutch, compressor, evapertor, etc. The whole nine yards, and a recharge. For the last year the ac has been blowing ice cold. But lately I've been noticing a problem, if I'm idling the air blows warm, but if I rev the engine slightly or start driving then it starts to blow ice cold again. Any ideas what the problem could be? Thanks guys.

norcalsvx

mine did that it was a clogged evap.canstier

anotherjeff

Low on coolant... What does the sight glass look like?

INFINITY

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Bumpin' Yota

subscribed! when my ac worked WAY back in the day it did that

Real men dont need AC! LOL jk

904_runner

Haha, my AC is all five windows down and the sunroof open!


Im too lazy to fix mine im pretty sure all the seals are toast.

Fo by Fo

When you say coolant do you mean freon?

abecedarian

I'm sure freon is what was meant.
the sight glass should show no foaming or turbulent motion, except for maybe a single bubble bouncing around reflecting refrigerant motion in the system. this is for R12, btw. for HFC134a, the sight glass is not reliable since charge levels are different than for HCFC12.

If it blows cold with only a 100 rpm or so boost to the idle speed, I'd guess you're either low on refrigerant or the AC idle up valve needs a tad tweak to raise the idle with the compressor on.

TORTIS

iTrader: (1)

www.ackits.com these folks have the parts. their on line forum is the best on the net. great advice and good parts.

Fo by Fo

Well I charged it up with some more freon today, and it didn't seen to fix the problem. While I'm driving down the road the A/C would get down to 55 degrees or so, but at idle it'll get up to 100 degrees over time. One thing I noticed is that the little black electric fan right behind the grill doesn't always come on during idle, could this be the problem?

Fo by Fo

Any idea's guys?

Fo by Fo

I'm thinking I'm going to check the A/C relays this weekend.

scrid

Mine does the same thing at idle, but when cruising down the road it gets down to a chilly 40 degrees.

deserthound

You should be idling at about 950-1000 rpms at idle with the AC running and the Idle-up circuit functioning. If so and the compressor clutch is disengaging at idle, adjust the cut-off control on the AC amplifier to lower the cut-off speed.

Fo by Fo

Ah, interesting, because with the A/C on full blast its only idling at 400 RPM, and if I hold down the gas a bit, causing a faster idle I notice the A/C is much cooler. I'm looking in my factory 4runner repair manual but cant seem to find any information on the Idle-cup circuit or how to test it, could it be listed under a different name?

deserthound

I didn't say exactly what I meant in my reply. Since the normal idle is about 750-800 rpm, when I test the idle-up circuit, it kicks the idle up about 200 rpm to 950-1000. Under normal operation, idling at 800 rpm and turning on the AC, the compressor will drag down the rpms a couple hundred and the idle up circuit pulls it back up to the normal range. The picture here "http://www.ruralinternetservices.com/postpic" shows the 2 components involved. #1 is simple a relay, except instead of switching electrical currents, it switches a vacuum. When 12 volts is applied, the switch applies vacuum to #2, which boosts the idle speed, adjustable via the large white screw on #2. My 86 FSM has the VSV test procedure in the AC section under "Inspection of VSV".

Fo by Fo

I also heard a weird noise coming from inside the dash last night, I think I'm going to pull the glove box and check out the condenser. I cleaned it out a year ago last summer when I replaced the whole system.