A/C : VSV (vacuum switch valve) and idle speed adjustment

**badkuk** · July 9th, 2006 06:05 PM

i recently had the A/c fixed on my ride(ae92, 2e engine). nagkataon kasi na walang mahanap na VSV, kaya tinaasan ng mga mekaniko ung idle speed para lumamig daw pag naka idle. needless to say, gas consumption took a nosedive B)

it turns out that the vsv for the ae92 XL is really hard to find; two of the shops i asked said either orig or surplus lang daw meron. one shop though offered me a VSV that's intended for the tamaraw fx. According to them, pwede daw sa ride ko. although not very scientific, i compared the dimensions of the replacement vsv with the original one, and mukhang pareho naman.

just this afternoon i took to adjusting the idle speed para medyo gumanda mileage. i'm doing this half blind, since i don;t have a tacho. My question is would the engine die if i set the idle speed too low, and turning on the A/C at the same time? To my understanding kasi, the VSV's job would be to make sure that never happened, right?

Another question: di ba parang useless to fiddle with the idle speed adjustment since the VSV would up the revs anyways?

ung idle speed adjustment screw ba is the one that's mounted on a 45 degree angle? pag clockwise/padiin is higher idle speed, if counter clockwise/paluwang = lower idle speed?

btw, notice ko lang that there's very little/no reference to the VSV on most repair manuals/sites; i only encountered the VSV term on a locally published book dealing with car A/Cs

**wildthing** · July 11th, 2006 05:54 PM

VSV nasa vacuum diagram madalas.

ung idle will control the cable that pulls the throttle for fuel release...the screw is in that area (along with the cable). Run the engine when you turn this to know which is the right way.

It is not useless, eto ang nagkokontrol ng low idling pag hindi naka-engage ang A/C.

any other screw is not for idle but like for air mixture sa mga breathers....perhaps.

**kupaloids** · July 11th, 2006 07:08 PM

Dami namang pwedeng ipalit dyan from other car models. Altough you might need some modifications, it will still work. Kung tama ang pagkaka intindi ko, yung switch/valve lang nag nasira at hindi yung mechanism mismo. Simple electric wiring at vacuum hose lang naman ang naka lagay dyan.

Useful yan kasi kung nag adjust ka ng idle though idle screw, kahit patay ang A/C mo e laging mataas ang RPM mo, let's say 1100 to 1200k RPM +/- which results to high fuel consumption. Kung may VSV ka (idle up), tataas lang ang RPM mo kung naka on ang A/C compressor.

Tama yung sinabi ng A/C tech mo, na pwedeng ipalit dyan yung galing ibang kotse which in your case is from FX. IMO it doesn't really need an exact replacement, you just need to find something that does the same function.

Just my 2.

**jim** · July 11th, 2006 07:24 PM

Originally Posted by badkuk

just this afternoon i took to adjusting the idle speed para medyo gumanda mileage. i'm doing this half blind, since i don;t have a tacho. 1. My question is would the engine die if i set the idle speed too low, and turning on the A/C at the same time? 2. To my understanding kasi, the VSV's job would be to make sure that never happened, right?

3. Another question: di ba parang useless to fiddle with the idle speed adjustment since the VSV would up the revs anyways?

4. ung idle speed adjustment screw ba is the one that's mounted on a 45 degree angle? 5. pag clockwise/padiin is higher idle speed, if counter clockwise/paluwang = lower idle speed?

1. It's not good to set the idle too low. 2E idle speed should be set to 800.
2. Yes the VSV will make sure that you get the right idle speed when the A/C is ON.
3. If you think that your idle speed is normal then there is no need to fiddle with it.
4. Yes, that's the idle adjustment screw.
5. Correct.

I have done numerous trials and errors sa 2E engine ko until I got the correct settings. Hirap ng walang tachometer. Kelangan mong maging sensitive pag naga-adjust. Pati yung air mixture adjustment nagalaw ko rin.

**finchy18** · July 11th, 2006 08:47 PM

Originally Posted by jim

1. It's not good to set the idle too low. 2E idle speed should be set to 800.
2. Yes the VSV will make sure that you get the right idle speed when the A/C is ON.
3. If you think that your idle speed is normal then there is no need to fiddle with it.
4. Yes, that's the idle adjustment screw.
5. Correct.

I have done numerous trials and errors sa 2E engine ko until I got the correct settings. Hirap ng walang tachometer. Kelangan mong maging sensitive pag naga-adjust. Pati yung air mixture adjustment nagalaw ko rin.

jim is right..

**badkuk** · July 15th, 2006 07:51 AM

thanks all for the replies B)

pansin ko dun sa idle screw adjustment, parang dalawa lang ang rpm levels. i turned it about 7-10 times bago ako nakanotice ng difference sa rpm level, and hindi gradual ung pagbabago ung rpm --bigla na lang siya tataas/bababa after the 10th turn. ganito ba talaga ang behavior?

Originally Posted by jim

If you think that your idle speed is normal then there is no need to fiddle with it.

tinaasan kasi ng mekaniko to compensate for the busted VSV sir, kaya ramdam ko ung higher than usual revving. i could've just returned it to the shop pero...parang gusto kong butingtingin e :D

this may seem weird, but nararamdaman ko rin na parang me humihila sa gas pedal while running. VSV at work kaya? medyo palyado kasi ung compressor, nag oon/off ng sarili. duda ko nahahatak ung throttle pag nag on ang aircon. the effect is that the car seems to surge once in a while, gawa siguro ng biglang pagtaas/baba ng rpm?

sir jim, di kaya pwede bumili nung aftermarket tacho to measure the rpm level? ung tipong stick on lang sa dashboard -- pero in this case, gamitin mong parang handheld?

**calcite** · July 19th, 2006 09:01 AM

You can try to find a hand held engine analyzer. It is a very useful tool since it is a tachometer, voltmeter, dwell meter and ohmeter rolled into one. Very useful in setting idle speeds and working on car electricals.

The VSV actuates a vacuum diaphragm which is connected to the throttle plate. This vacuum diapghram pulls on the throttle plate a little in order to increase the engine rpm whenever the AC turns on. That is why you feel as if something is pulling on the throttle cable since the throttle cable is attached to the throttle plate.

I think pwede replace any vsv since it's only function is to switch the vacuum on/off. As long as you can bolt it to your engine bay and the hoses are the same diameter, ok lang siguro.

**acenie** · July 19th, 2006 02:20 PM

yes u can use any available VSV u can buy new or buy surplus with the same mounting

**nizmo** · July 19th, 2006 06:45 PM

baka walang supply yun VSV mo located sa throttle body. hanapin mo yun VSV ng AC. or tanggalin mo isa isa yun mga actuator, piliin mo yun hindi nag rerespond. o kaya pag alam mo na kung anong actuator yun. gupitin mo yun wire suplyan mo ng 12V battery yun red yun black sa ground mag rerespond na yun sa AC mo.