an1176

Okay so I've searched my behind off and some are having my issues but I can't find any solutions to my AC problem. Truck is a 94 22re. The AC works fine driving down the road, but once stopped it won't idle up. Here is what I know or think I know. The amplifier knob controls at what RPM the compressor kicks on. The VSV is just a valve that opens to let vacuum in or not which causes the idle to raise. The AC idle screw controls the amount of vacuum let in to VSV thus what RPM the engine idles up to.
1. My amplifier works fine I've turned it both ways and the compressor will kick on or off accordingly.
2. VSV makes clicking noise so I assume its working and I've tried several VSVs with no idle up no matter how much I unscrew the idle screw.
3. I've connected the two hoses to VSV together (bypassing the VSV) and still no idle up unless I screw in the idle screw all the way shut then unscrew it again to desired idle. As long as I keep the AC running it stays idled up, but if I kill the engine or AC, even with hoses still connected together (VSV still bypassed) the idle will go back down unless I screw the idle screw all the way in and back out again.
I'm at a loss and have no idea where to go. I've even taken the idle valve off and cleaned it and put it back on. Checked hoses to see if they are plugged and they are fine. Please help!!!!

BigBluePile

iTrader: (3)

Hmmmm...possible vacuum leak else where in the system or a cracked fitting? Did you try a different A/C idle screw?

coryc85

Is your warm idle set properly? How about some pictures and maybe a diagram of how your vac lines are routed? I've never really heard of anyone's idle up diaphragm being bad, but who knows maybe it is, I'm more inclined to think your vac lines are just not routed correctly and if we could see some pictures, it might help.

an1176

an1176

scope103

If connecting the port on the plenum directly to the unmetered air from the air box doesn't raise the idle, then I would first suspect that the port on the plenum is blocked.

an1176

horunner1x

I’m having a problem very similar to this. I’m curious of the fix.

an1176

Dseldown

Could also be the high side sensor switch as well!!....gotta remember that the high sides function is to tell the ECU to break ground to the compressor clutch to disengage it, if the head pressure gets too high!!.....Just as the low pressure side switch does the same if the freon or pressure goes too low to protect your compressor from burning up!!....the fact that you can activate the clutch by jumpering eliminates the clutch being faulty!!...Question to YOU??... did you jumper 12 volts or induce ground to the compressor clutch??...reason Im asking is because on my Yota, 12 volts is always present at the clutch, and the clutch engages when ground is induced thru the ECU, so keep the ground in mind before proceeding with these other suggestions!!....Chances are you most likely have a pressure sensor switch malfunction!!... quirky compressor cycling as you described usually indicates a switch going bad before total failure!! The very last fault I would even consider is a faulty ECU, which if it leads to that would most likely be a pin connection to or from the ECU cannon or connector plug, instead of the electronics itself of the ECU!!....Ive bypassed pressure switch,s before, to check them!!...but if you can rig a closed position from the switch connector to the ECU, and the clutch engages each time you try it, then you've found your BAD pressure switch!!...The HP switch is normally in a closed switch position....If the head pressure gets TOO HIGH, It will open at a preset pressure setting, telling the ECU to shut down/disengage the compressor clutch. If it is stuck in the open position, it will tell the ECU to keep the clutch disengaged forever, until it gets the correct voltage again to induce ground/ or voltage back to the A/C clutch!!...Hope this helps you out!!

an1176

an1176

mholme

Can you take a picture of what it was that you jumped? It seems kind of strange that you had a working AC system and then nothing at all, and that jumping something that wasn't the pressure switch made it work again.

Dseldown

Ok I thought that you already did that!!...jumpering a direct connection to the clutch to determine that its OK!!....What I was saying for you to do is separate the high side connector switch and jumper across the connector to see if the clutch engages....do the same on the low side if you get no results from the HSide....the high side switch can be found by tracing the little line, when you come to it you'll see it immediately its a 2 pin connection!!....The low side or suction side of your system is the fatter diameter of the 2 lines, do the same to locate the low pressure side switch and attempt to jumper across it to simulate a closed switch to the ECU!!...if 1 of these 2 switches are bad, you'll see the clutch engage immediately pumping freon again, if you remove the jumper and the clutch disengages and then engages again upon re-jumpering...you've found your faulty sensor switch!!....I assume you have a volt meter, turn on your AC system to normal mode with engine running and then check to see if you have 12 VDC coming to the compressor clutch plug from the ECU, connect your black lead to chassis ground and with the red lead touch each pin separately to determine if in fact you have VDC to the clutch connector AT ALL!!....If you don't then it probably means your ECU is being told to not supply VDC because of one of the 2 pressure sensor switches being faulty/stuck in a open position!!....next thing to do is look real closely at the ground connection of the clutch to make sure its healthy, not corroded, broken lead. loose ETC!!...Remember that current cannot flow W/O a good source of ground to complete the circuit!!...Ahhh Im not sure where or if theres a A/C breaker, but it probably would be in the engine compartment as a bulky relay along with the other relays, as the fuse panel box is separate from that and doesn't host any relays, however I don't own a 4 runner so don't flame me if Im wrong!!....but all the other advice is spot on to determine what the true cause is of why your clutch wont engage...again you said that before it went totally bad it was cycling/acting up weird, and again thats usually textbook example of a faulty pressure switch going bad, because its flipping between open and closed at the wrong/but correct pressures!!

Dseldown

No thats not strange at all!!....because he eliminated the ECU to see if the clutch would engage!!....If the clutch is good, it'll engage immediately upon jumpering it!!...as long as the compressor is pumping freon, the sysytem will start to cool if the rest of the system is healthy as normal!!...But its not a repair!!.... as you would risk the head building too high a head pressure and blowing the seal on the compressor or worst!!.... Ive done this before [jumpering the compressor clutch] for short periods of time to purge air outta of a system, when we didn't have a vacuum pump to do it correctly!!.... and took a field repair chance!!...meaning NOT TOO LONG, to avoid burning up the compressor, to try and get a system to charge and go for awhile or just 1 more summer on something that we didn't care about that much about...meaning low value cars or trucks!!

an1176

an1176

mholme

an1176

mholme