AC idle up issue (1 Viewer)

[LandoNick]

I have a 87 FJ60, smogged. Start it, get it warm to operating temp. idles at 700-725ish. Turn AC on idles up to 1,000. VSV has vacuum to the actuator runs perfect for about a minute then the actuator loses vacuum and idle drops below 450-500 stumbling. turn ac off idles back up to 700. When the idle drops for no apparent reason there is no vacuum and the actuator. Is something happening to the diaphragm in the actuator? I think that part is discontinued. Any help would be great!

 

[pithicus]

sounds like a problem with the electric vacuum solenoid valve

 

[LandoNick]

sounds like a problem with the electric vacuum solenoid valve

It’s newer. How can I test it? Works for a minute then just stops?

 

[pithicus]

How can I test it? Works for a minute then just stops?

Probably easiest to just swap in another one .[use one of the other ones on the truck to test]

 

[LandoNick]

This test?

 

[Spike Strip]

Test that the dash pot is holding vacuum.

Correct, that part is NLA, but there is a guy in the Middle East who was selling them. Not cheap: $175

 

[pithicus]

This test?

Not sure that will work if the problem is sporadic. Easiest to swap in another one to be sure.

I had a similar issue a while ago and it fixed itself, then later it stopped working completely, then started working again! go figure.
Now the fast idle stays on when I turn the a/c off and remains on until I restart the engine. I have some gremlins. Winter is here now, so I'll adress it when the weather warms up.

 

[LandoNick]

Test that the dash pot is holding vacuum.

Correct, that part is NLA, but there is a guy in the Middle East who was selling them. Not cheap: $175

Dash pot??

 

[pithicus]

Dash pot??

I think spike means the vac module on the carb. ??

 

[LandoNick]

I think spike means the vac module on the carb. ??

Are they rebuildable at all?

 

[pithicus]

Are they rebuildable at all?

I doubt it. You might be able to modify a similar one to fit

 

[pithicus]

Re the VSV test. Hook it up to battery and do the blow through test. Leave it connected to bat and go have a coffee or something. Then check the blow through test again. If it's still ok, then the VSV is likely ok.

 

[Spike Strip]

Actuator, generically is a dash pot.

Put a tube on it, pull vac with a hand pump or suck and see if it holds vacuum. If not, the diaphragm inside is bad. Not serviceable that I know of...

The VSV is just a normally off valve. When power is applied, full manifold vac to actuator. A/C amplifier will switch VSV on/off according to evap temp.

 

[LandoNick]

Put power to the VSV audible click. Sucked on hose from actuator (a sentence I don’t usually type). And the sucking moves the arm. Obviously not holding suction on for a very long time because that’s tough.

 

[LandoNick]

What kind of volt reading should I get from the vsv

 

[pithicus]

What kind of volt reading should I get from the vsv

VSV is an on/off 12v actuated device. should be 12v going in to it.

 

[Spike Strip]

VSV is either on or off. Voltage to it should be batt voltage 12v or so.

Suck on a hose directly connected to actuator then crimp the hose and see if it holds vac. It's possible you may have a cracked tubing or something like that, but you have to rule out components individually first.

 

[LandoNick]

12v at the connector to the VSV. Clamped hose is holding. Looked at my fuses notice a 15 amp in the ac spot when it should be a 10 I believe. Switched it to a 10 amp. Issue still there

 

[LandoNick]

What am I missing. Frustrating it works then doesn’t

 

[LandoNick]

Not the original VSV. Should work the same or no?