2.0 TS Idle Drops Dangerously Low With AC On And Speeds Higher Than 30KPH - Alfa Romeo Forum
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2.0 TS Idle Drops Dangerously Low With AC On And Speeds Higher Than 30KPH

What the title says really. And this only happens with the AC on.

If I depress the clutch to come to a stop while the AC is on and at speeds over 30kph the idle drops the nearly zero before settling regularly. The issue doesn't happen with the AC off at all, and if I slow to under 30kph before depressing the clutch it works just fine.

Any ideas?

I've narrowed it down to either the Q20 four way pressure switch OR the speedo signal that goes into the climate control ECU (Pin B6), and my thought is to cut that wire to see if it fixes it in the hope the climate control ECU defaults to when the car's stationary.
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(Post Link) post #2 of 5 Old 4 Weeks Ago
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What is the A/C gas pressure?
High gas pressure can cause the compressor to work too hard which may affect engine idle.
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May I ask if the brakes seem to lose effectiveness at anytime during this? Like you momentarily loose brake boost?
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Have you tried resetting the idle actuator?

Turn on the ignition for 90 secs but do NOT touch the throttle or start the engine.

Turn off ignition for 90 secs

Turn on and start engine but do NOT touch the throttle and leave to idle for a few mins.


The other think to check is the breather pipe that runs to the intake manifold. It's not easy to see but if you take the engine cover off there are two hoses from the cam case: one goes to the intake just before the throttle and the other goes behind the throttle body to the intake. At the end is a plastic valve housing .. the mounting tabs snap and it lets in air at the wrong time which can kill the engine. I don't think you can get new ones now so don't break it!!

Several years ago I had the stalling problem but it wasn't related to the a/c. The valve at the end of that hose had been removed to do some engine work and it was missing a bit .. the valve inside! A new valve sorted it.

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Quote:
Originally Posted by gazza82 View Post
Have you tried resetting the idle actuator?

Turn on the ignition for 90 secs but do NOT touch the throttle or start the engine.

Turn off ignition for 90 secs

Turn on and start engine but do NOT touch the throttle and leave to idle for a few mins.


The other think to check is the breather pipe that runs to the intake manifold. It's not easy to see but if you take the engine cover off there are two hoses from the cam case: one goes to the intake just before the throttle and the other goes behind the throttle body to the intake. At the end is a plastic valve housing .. the mounting tabs snap and it lets in air at the wrong time which can kill the engine. I don't think you can get new ones now so don't break it!!

Several years ago I had the stalling problem but it wasn't related to the a/c. The valve at the end of that hose had been removed to do some engine work and it was missing a bit .. the valve inside! A new valve sorted it.
This is really stumping me. The Idle Speed Actuator is fine, my mechanic's tested the actuator on a lift and found absolutely no issues whatsoever. I'm looking into the ABS issue that Marlon had reported on the 156 Twin Spark.
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