Hyundai Forums banner

1 - 4 of 4 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
So, whenever I turn the AC on with my Lantra the idle will drop to near chugging.

It doesn't stall out but does go to the point lights dim due to the alternator not spinning fast enough.

Now, you may say the compressor may be broken or putting too high of a load on the motor but here's the kicker, it does it without the compressor being connected.

I discovered this after taking off a bad bearing, even with the belt completely off the AC unit if I turn it on the idle still drops to about the same spot.

So, is this normal for a 1992 J1 Lantra or is a sensor or something bad?
If its bad what could be causing it?

For reference, this car hasn't seen a road since 2011 and I've been slowly getting it back ready for the road, this is one of the last things on my list before I attempt to get a road worthy.
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,330 Posts
The engine PCM should increase the idle speed when you turn the AC on to compensate for the additional load on the engine. The compressor isn't the only thing to load the engine though. The solenoid that engages the compressor clutch is quite a heavy electrical consumer, so the alternator also puts load on the engine when the AC is switched on too even if the AC compressor isn't being driven.

The cause of the low idle speed is probably a fault with the idle control valve or it's wiring. If you have a multimeter that can measure duty cycle you could use that to check the valve control signals. If the engine computer is altering the valve control signals in response to the AC being switched on, the valve itself is probably mechanically seized.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3 (Edited)
The engine PCM should increase the idle speed when you turn the AC on to compensate for the additional load on the engine. The compressor isn't the only thing to load the engine though. The solenoid that engages the compressor clutch is quite a heavy electrical consumer, so the alternator also puts load on the engine when the AC is switched on too even if the AC compressor isn't being driven.

The cause of the low idle speed is probably a fault with the idle control valve or it's wiring. If you have a multimeter that can measure duty cycle you could use that to check the valve control signals. If the engine computer is altering the valve control signals in response to the AC being switched on, the valve itself is probably mechanically seized.

Oh wow forgot about this post, my bad. Eventually worked out the load was actually the radiator fans. Forgot how much power those can pull.

I only have a cheapie meter so no cycle measuring. It still seems to be able to control it's rpm when warming up (goes lower).
Thinking about it, could the issue be that my timing is way off? Had the cam sensor out when doing repairs and have yet to re-time it.

Yep, months and still haven't got that sorted. Been working on fixing a rusted exhaust and leaky rocker gasket and busted window regulator and loose gear shift and broken interior fan....A few things.
 

·
Registered
Joined
·
6,597 Posts
Oh wow forgot about this post, my bad. Eventually worked out the load was actually the radiator fans. Forgot how much power those can pull.

I only have a cheapie meter so no cycle measuring. It still seems to be able to control it's rpm when warming up (goes lower).
Thinking about it, could the issue be that my timing is way off? Had the cam sensor out when doing repairs and have yet to re-time it.

Yep, months and still haven't got that sorted. Been working on fixing a rusted exhaust and leaky rocker gasket and busted window regulator and loose gear shift and broken interior fan....A few things.
You would do well to clean the TB and IAC valve.
 
1 - 4 of 4 Posts
Top