RylerTust

I'm new to Toyotas. Used to jeep Cherokees but finally got smart and got a toyota.
Well here's my problem. Only when the A/c button is engaged the engine will surge and, well not miss, but bog down really low (about 300 rpm) won't die. It'll do it when idling and when moving it'll do it in 1-3rd gear slightly. 4-5th are fine. Is this a vacuum issue? I know next to nothing of this truck and need help.

Thanks guys.

1990 4runner sr5
22re
5speed
4x4
233k miles

RylerTust

Oh and the Ac lever has to be on aswell as the Ac button on.

TrikeKid

There is a vacuum switch that is supposed to kick the idle up to compensate for the load of the AC compressor, sounds like yours is either cracked and leaking or the lines leading to it are dry-rotted/leaking/missing. Basically you turn the AC on and it's creating a vacuum leak.

RylerTust

Thanks so much man! I'll look for it tomorrow. I can't see anythin out of sorts. Then again I'm a Martian to this engine haha

z31freakify

where is this vaccum switch, can you post a pic please , I also have the same problem

RylerTust

Yea I can't font anything out of sorts. Pic please?

TrikeKid

I don't have any pics handy but it'll be on the valve cover with a couple others if it's still on the rig.

RylerTust

I'll look for that. Would it cause only to surge and bog when Ac is engaged? If its not there what should I do? Ahahah. Maybe get happy with some starting fluid on the vacuum lines? Hahah

TrikeKid

It should be the only thing that'd make it surge with just the AC on and be 100% the rest of the time.

RylerTust

Okay thanks man. I'll check it tomorrow and let you know.youre a great help.