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1992 22RE in my sig, If I could get a diagram on what to test on the AC amplifier, that would be helpful. Like I mentioned the black knob on the AC amplifier is all the way to the lowest RPM setting. Not sure if that matters. Thanks
He has tested the bypass valve, it passed, when he manually connected the two vacuum lines that should goto the vsv it idles up like it should.
Has also measured the vsv wires, one has battery voltage like it should and the other which should go from OPEN to ground (this vsv is switched ground side) shows 5 volts. This tells us the amplifier circuit is malfunctioning, the transistor isn't closing fully. 12v-5v=7v, seven volts and probably next to zero current isn't enough to operate the vsv solenoid.
Slayer you can try running those voltage tests with the AC off, I expect you'll still see 5v on the amplifier side of that plug.
So I took out the glove box and noticed a plastic thing containing 2 fuses a 30amp and 10amp the 10 was blown, so I replaced it then proceeded to do the harness testing, it passed all the test so I decided to pull out the amplifier and I find this.
I order 10 replacement transistors for $2.70 plus shipping, hopefully this fixes my issue.
So I took out the glove box and noticed a plastic thing containing 2 fuses a 30amp and 10amp the 10 was blown, so I replaced it then proceeded to do the harness testing, it passed all the test so I decided to pull out the amplifier and I find this.
I order 10 replacement transistors for $2.70 plus shipping, hopefully this fixes my issue.
Looks like you found a failure point, good work, double check the/any diode connected to that section of the circuit. The black one with the silver band is a diode it should not only ass current in one direction and has a specific voltage drop in the pass direction.
Looks like you found a failure point, good work, double check the/any diode connected to that section of the circuit. The black one with the silver band is a diode it should not only ass current in one direction and has a specific voltage drop in the pass direction.
I'm guessing you made sense of that but just in case, the diode should only pass current in one direction.
Without looking at the circuit layout this is a bleeder diode (that's not the right term) when the transistor turns off there is a backwards surge of current that bleeds off thru this diode to protect the transistor (which has a much smaller diode) from letting out the "magic smoke".
A Flyback diode is needed when the switching element (transistor, relay) is switching an inductive load. The A/C Amplifier drives the A/C Clutch (a big inductor), but I would think that would be switched by the relay (the big black box). The relay would probably require a flyback diode (there are two diodes in the picture) to protect its contacts. Could the transistor also need a flyback diode to protect it from the much smaller inductor that is the coil of the relay?
The forward voltage drop referred to by Co_94_PU should be 0.7v (silicon diode). Most multimeters today have a "diode" function that pass a small current through the diode and display the voltage drop, just for that purpose. It will usually work in-circuit, so sure, test all the diodes.
There is a mark on the adjacent capacitor as well. It's a ceramic, which are legendary-tough, so you should still be okay.
You almost make me wish I had taken out my amplifier to (try to) reverse-engineer it.
So an update, I soldered in a new transistor didn’t seem to work, so I ordered a new amplifier, then a few days later the old one started working. So I have a backup if needed. I appreciate all the help guys.
Stoked this works perfect. My truck is operating better than ever! I made a video about the fix. It’s nice to have a brand new part too instead of an overpriced used one that won’t last as long.
Should there be a suction sound when AC is on or do I have a possible vacuum leak somewhere?
I'm bumping this thread back up to the top since getting the AC idle up working properly is something we all face. It turns out the V6 diaphragm is still available, which I didn't expect. I still have some troubleshooting to do though before I get the system completely sorted out. My situation is that the AC and idle up system were working perfectly earlier in the summer. One day I had the truck out and noticed that the idle-up was erratic, making the idle rpm surge between 600-1000 rpm when the air was running. If I turned off the AC, the idle smoothed out at 850 rpm as it always had. The idle-up quit working after that day. I went ahead and replaced the diaphragm as a maintenance item while I still could, but the old one actually tested ok. I guess the next thing to do is test the VSV.
OK I found a much simpler way to do this. The trick is that the extra port on our diaphragm that goes to the power steering pump is not necessary. The diaphragm does nothing special for the power steering pump except pass through the air intake line. You can use a splitter for that.
Take out the old idle up diaphragm shown here (middle left).
Screw in the new diaphragm. I got over excited and started hooking up lines before I took a picture.
Run the larger tube from the intake to the splitter. That same size tube goes to the diaphragm on the left. The smaller tubing goes to the power steering pump on the right.
Pics of the whole setup.
Works like a champ. Engine idles at 750 rpm normally and now idles at 1000 rpm when I turn on the AC. Total cost about $30 and 5 minutes to remove and replace the old one. You may need some slightly longer vacuum hoses as well.
I just joined this forum and it’s nice to see this little trick here. They told me the part was discontinued. Thanks to your post I ordered the diaphragm from Toyota parts express for cheap and the switch from 22re performance. I have an 86 4x4 pickup and had to tear out the motor and start from scratch. Truck is running great and ac works but I had to adjust the idle air screw to stop it from stalling. Now it idles at 1100 when it’s not on which isn’t terrible but I like things to work the way they should. 750 rpm without ac on and around 850 with it on. Hopefully this will work. Looks like it does according to what you said. I’ll check back in and let you know. Thanks
Great to hear this trick might fix things for you since the original part was discontinued. Sadly I sold my truck but would really like to hear if this worked out for you. I'm sure others will be curious. Take a picture or two. This is the only forum that I know if where this trick was posted even though this engine is also in other vehicles, like the Celica. There are various configurations for this set up. For example if you don't have power steering then you may not have the power steering idle up tubes and therefore don't need the "T" coupling. Without PS, the vacuum tube from the front of throttle body will just go straight in to the large tube on side of diaphragm. You said you bought both the diaphragm and the switch. Your existing idle up switch valve (VSV) may work. Its just an electrically activated solenoid. If on the car just unplug the harness from it and you should be able to activate with a 12v test lead from battery and ground. You should be able to hear a click or at least feel it with your finger on it. If it clicks then likely it works. That switch has vacuum applied to it all the time from the small vacuum tube, but until its activated by the compressor kicking on, it won't open and apply vacuum to the diaphragm, pulling the diaphragm down and opening the bypass tube inside the ac idle up diaphragm unit. Until I took it apart I did not understand how this worked. The official Toyota manual does not illustrate how it works very well. The only part in the ac idle up diaphragm that can really fail is the rubber diaphragm itself. If the rubber gets dry/stiff and cracks then it has failed and your idle will not idle up with ac on.
Make sure you set engine idle correctly with ac off. Then with ac on, and all ac idle up components including signal to switching valve solenoid from compressor working, set ac idle screw on the top of diaphragm when compressor kicks on. You can test the harness from the compressor to the VSV too for voltage when ac compressor kick on. The only thing that diaphragm and switch valve (VSV) do is reroute air (a bypass) from front of throttle body to intake plenum. That is what bumps the idle up. Air just bypasses the closed throttle body. How much it bumps the idle up is determined by the screw on top of ac idle up diaphragm. Let us all know even if you don't have picks. Good luck!
Aug 31, 2020 | 01:32 PM
