Oil Pressure drops. Engine struggles to idle. When using Aircon? AE93 Seca

[justin_es]

Good day peoples.
Now ofcourse i wait till the heat waves start before i decide to get this sorted as i have known about it for a few months now haha.

Anyways as heading suggests. When i turn the aircon on in my AE93 Seca the car struggles to run.
When i pull up at the lights the oil pressure drops to almost nothing (Just the standard oil pressure gauge) and the car struggles to idle, Sometimes even stalling.

Does anyone know what is more than likely causing this?

Cheers in advance.

[sc400]

do you get any cool air from it as sounds like the compressor is seized with the engine cool and off try and turn the compressor by hand (the centre bit of the pulley) should be able to turn easily

[justin_es]

it does actually and its quite cool lol. so plenty of gas BUT in saying that i had a look earlier (well more a listen) and i get a hell of a rattle when i turn the aircon on so im thinking the compressor is rooted.

Just when it all started happening i decided to not risk it with the oil pressure being so low. Well according to the gauge. Are those stock gauges accurate?

[lexsmaz]

I doesnt sound too healthy for your compressor but if you just rest your foot on the accelerator does the car run well & seem to respond well, if all feels good, i would say its just the idle up unit for the A/C which is not working, not sure on your car if it runs through the ECU & stepper motor or it has a bypass solonoid fitted ..

Low oil pressure on the gauge i would say is a Lazy gauge, but get it checked if you want to be safe ..

[TERRA Operative]

Does the aircon idle up valve work ok?

[Hiro]

Oil pressure gauge dropping is almost certainly linked to the car almost stalling - remember that the oil pump is driven directly by the crankshaft, so you would expect the pressure to be low at idle, and to be worse if the car is struggling to even maintain idle

[justin_es]

Thats why im trying to figure out why the oil pressure would drop so low when turning the aircon on.
Compressor still turns as i receive cold air when its on?
Maybe partially seized so the motor is working double time to turn the compressor properly?

Like i said above i get a bit of a rattle when aircon is on but not certain if its the motor due to no oil pressure or if its the aircon compressor.
When aircon is off oil pressure gauge sits at the lower end but inside the range of what the owners manual deems to be normal.

I dont use the aircon at risk it being the motor making the noises.

[Hiro]

Thats why im trying to figure out why the oil pressure would drop so low when turning the aircon on.
Compressor still turns as i receive cold air when its on?

As I said, the extra load of the air-con is causing the engine to struggle to maintain idle (which is why there is an idle-up circuit for the air-con, just as there is for the power-steering as well as cold idle) which in turn causes oil pressure to drop (as oil pressure is linked to RPM)

[justin_es]

Actually you know what.
I think i might look further into the idle up curcuit first before anything else as on cold starts it idles at like 2100rpm so the idle up circuit is probably stuffed.

[Hiro]

Actually you know what.
I think i might look further into the idle up curcuit first before anything else as on cold starts it idles at like 2100rpm so the idle up circuit is probably stuffed.

~2000rpm is normal for cold idle on a 4AGE, but it is controlled by a separate circuit (wax pellet bypass valve) to the rest of the idle-up circuits.

[caam]

I agree with it being the idle up, my 2TG wouldn't idle with the aircon switched on because it had no solonoid to feed more air.
Would run it while driving then switch it off for traffic lights as to not stall it. sucked.

[Hiro]

Or just give it a little more throttle at idle, not that hard really...

[trdee]

as above. a/c idle up solenoid would be the first thing to check.

low oil pressure would be a direct result of the car idling really low/stalling. not the cause, the result. fix the idle/stalling, and you'll "fix" the low oil pressure

[TERRA Operative]

I had no idle up when I stuck a 4AGE throttle body (wax pellet) onto my 4AGZE (ECU controlled), even with cracking the throttle body a bit, the idle was all over the place when the A/C was on.

If it turns out your AC idle up valve is ok, but the control isn't working, you could just wire it to the AC clutch wire. If you want to get fancy, you could also put a RPM sensing relay in too so the valve only opens when the AC is on and the revs drop below a certain level.

But I reckon it's probably the valve itself.

[justin_es]

Excelent.
Thanks guys.
Ill definately be getting this sorted very shortly.

Gotta get something else done so while its in i will get this looked at also

:-)

cheers.