A/C Idle up (1 Viewer)

Joined
Nov 21, 2018
Messages
15
Location
Kuwait
Hello,
Hope all are safe

Patient history: FZJ80 that was converted from auto to manual transmission (has a manual transmission ECU). Throttle body is clean with a new gasket. New plugs, fuel filter etc.
When the A/C is switched on, it does not idle up and the RPMs drop down to ~600. When the A/C is switched off, the RPMs increase to 800 or so.
Another issue that may be related. Once stopped after driving, it immediately idles at 1000-900 RPM and steadily decreases to around ~600 RPM with the A/C on - this process takes around a minute.
Today after replacing the radiator and removing the +/- cables and starting the car, the idle increased up to 2000 RPM and returned back to normal after driving around a bit.
I cleaned the IAC valve but did not really see any difference. Engine was just rebuilt and the whole throttle body has been cleaned but this issue was before the rebuild and remains.
Searching around it seems that a specific A/C AMP sends an idle up signal but I think the issue is more involved than just this.

Any ideas? Thank you in advance and stay safe!
 
Joined
Nov 21, 2018
Messages
15
Location
Kuwait
Is your throttle cable tightened within spec?

Just checked the cable and the insulation is cracked
I'll replace and check. I understand it would interfere with the idle but would it also affect AC idle up?
Thank you for your reply and thoughts
 
Joined
Mar 30, 2009
Messages
721
Location
Indiana
Just checked the cable and the insulation is cracked
I'll replace and check. I understand it would interfere with the idle but would it also affect AC idle up?
Thank you for your reply and thoughts

Check the actual cable tension/slack at the throttle body bracket where the trans cable, cruise control and throttle cable all meet (at least on the 93/94). I had too much slack in my cable when I put a new one on and the idle was both too low and too high at different times. Correct tightness and now perfect.
 

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