Idle won't kick up when Air Conditioner turns on !

[linthead]

The RPMs drop to abot 600 on my 1988 Celica with the 3sgte engine when I turn on the Air.
I'm not getting a single at the TPS to kick it up! Other than a bad CPU, what can be the most common problem??

[flex-appeal]

the aircon is supposed to stop working when the car is idling. so you shouldnt be looking for a signal to up the revs, but a signal to stop the compressor.

[linthead]

Thanx for the reply "Flex". but according to my Haynes manual "A signal from the A/C amplifier allows the ECM to adjust engine speed to compensate for the additional load on the engine. "A code 51 will set if this signal is not present"

I'm not getting any codes!!

[flex-appeal]

well i cant remember what its called, idle stop control or something like that. apparently at idle it will disable the compressor , there may be a vacuum line or something to control it. the signal is sent to the ecu to adjust speed when the car is driving. to be honest i dont really know much about aircons , just remembering what the aircon repair guy told me when i had the thing fixed on mine.

[linthead]

The car runs fine and idles fine other than when I run the A/C and I come to a stop.I get plenty of cold air and the compressor is not overly noisy.Last summer I converted the compressor refrigerant to R-134a.
I normally idle at 850 RPMS.I tried increasing the idle to 1000 rpms but it still drops down to where it runs rough at a stand still. I have been scanning several messages boards for several weeks, and haven't heard of anyone with a similar problem. Hopefully an experienced Tech will respond to this thread with a good explaination and some helpful hints!!

[silverstreakin]

actually there is a vsv that went bad on mine. it was doing the same thing when the ac kicked on. the rpms would fall so low that the ac would kick off. i changed the vsv with a 50 cent piece from a junkyard. no probs!

look under the hood for the vacuum diagram.

[tsuave]

i hate to be a noob, but i have a 90 celica that does the same thing (idles rough with a/c on and idles rough when at a stop when in drive or reverse (a/c off)) whats a vsv? is there a code it will spit out when thats bad and how does one check if it is inop? i couldnt find any vacuum leaks. i was going to get a compression check done along with a whole vacuum check done done for $50 but i wanna check stuff on my own first.

Thanks

[ST185]

This is the A/C idle up control valve.
It's used to adjusted the idle when A/C is on.

[A Diddy]

^ownage

[tsuave]

i cannot find that adjustment on my 90 celica 2.2. maybe my problem is a bit diferent. my car idles at 850 ish and when i turn on my ac it rythmatically goes from 800 to 400 back and forth back and forth. and i think the compressor might be turning off and on. and if i recall the compressor turns off at idle or something like that....so is it a vacuum problem or something else?

[Pineapple]

It on the other side of the intake manifold.

[ST185]

Check the A/C VSV first

[tsuave]

ok so my vsv looks different than the pic posted, but the input is 12v when ac is on and 0 when its off, so i assume its the ac vsv. howver when shooting resistance across it i get 0 ohms which cant be good....my question is, where would one find that part online for cheap like....i ran my part number and it didnt come up.....has anyone had to replace one before.

[ST185]

Your best bet is junkyard.
Toyota dealer will charge your arm and leg for that.
Also, try Celicatech.com
There are always people parting out their cars.

[Pineapple]

You should be able to find the part from Camry and Corolla.