I know that this was touched on in a previous thread but no solution was ever posted. I have a 95 Pickup DLX 4x4 m.t. with the 3VzE. Apparently, the truck did not originally come with AC but the previous owner installed an aftermarket system. AC works fine but bogs down the engine and drives down rpms at idle. I ordered and installed an AC idle up valve from Toyota and hooked up the vacuum lines per the diagram. The vacuum circuit works fine but the vsv isn’t switching when AC button is pressed. In fact, I have no voltage at the grey connector at all. Can anyone tell me why?

 

It's not directly linked to the AC button being on, even in the factory system. You don't want it to idle up unless the compressor is actually doing work this requiring the extra engine speed.

You will have to provide more details regarding your specific aftermarket AC system, some important ones are what input and outputs does it have and exactly what are they connected to.

For example does your AC controller have an idle up signal? If it does is this signal switched ground or switched power? What is its current rating, do you need a relay attached or can it handle the load of the vsv switching?

 

Man, you lost me. I didn’t realize that it was so complicated. I thought once you hit AC button, compressor engages, vsv switches to increase rpms in order to compensate for extra load. I’m just assuming that the truck didn’t come with air originally because there wasn’t an existing idle up valve and the compressor is a Sanden 508 style. I have no idea what controls are in place. I thought it was basically plug and play. So, now what? What’s my next step? Where do I even look for the controller? I thought there was an AC amplifier behind the glove box or something. If there is no amplifier, couldn’t I just parallel the switch with the compressor/ clutch circuit and be done with it?

 

Nick, Did you ever figure this out? I'm having a similar issue on an OEM system. It only pulls 0.8v when the compressor kicks in. I can power 12v directly to the idle up valve and it works perfect. So it sounds like we have the same problem. Mines an 86 and it does have an amplifier behind the glove box.

 

I ended up tracing the power wire from the vsv connector back to the connector at the AC switch. Since I don’t have an AC amplifier, I verified which wire reads 12v with the switch on and installed a jumper wire between the pin for the AC button and the pin that goes to the vsv on the back of the AC button connector. Now, whenever I press the AC button it sends 12v to the vsv. I took the other side directly to ground from the connector at the vsv. It’s a bit of a hack, but it works perfectly. In your case, you may have an issue with the amplifier since you have an OEM system, but I don’t see why you couldn’t do the same thing.

 

Sounds like your problem was a PIN connector? Or did you run a jumper wire from the AC switch PIN to the VSV PIN?

I did some more diagnosing yesterday and it does look like the Amp may be bad. I spliced the 12v+ to the compressor clutch (that was running just fine) with the VSV. I thought I was going to get away with an easy fix. Now I have no AC and have to start pulling the dash apart to get to the AC switch. Maybe I get lucky and the switch wiring/PIN is bad.

 

My problem was that, without having an amp, there was nothing powering the vsv at all. I simply paralleled the 12v from the switch and sent it to the vsv. This way whenever the switch is engaged the vsv also gets powered.

 

Interesting