1992 High Idle Related to Disconnected AC

sweedespeed1 · Post by **sweedespeed1** » 17 Feb 2019, 12:14

Hi,
I have a 1992 240 with a high idle once warm that I haven't been able to figure out. Checked and rechecked for vacuum leaks. The AC electrical is disconnected, there's a broken wire coming from the bottom of the compressor that I'm not sure where it goes. Wondering if the ECU thinks the AC is engaged and it's increasing the idle to compensate?

lummert · Post by **lummert** » 17 Feb 2019, 12:58

Does you car have a switch on the AC Dryer/Accumulator?

sweedespeed1 · Post by **sweedespeed1** » 17 Feb 2019, 15:35

Yes, it does.

sweedespeed1 · Post by **sweedespeed1** » 17 Feb 2019, 15:41

There's a low pressure switch on the accumulator, and a high pressure switch on the line from the condenser.

Post by **jimmy57** » 17 Feb 2019, 15:52

If the switch on dash is off then all the stuff under hood doesn't matter. The power supply that the LH EFI control module would get its signa; from power being on the clutch circuit. If the wire to accumulator pressure switch is not powered and the wire from accumulator switch is not live then the LH module would not be upping the idle speed. The idle speed with a/c on is something about 925 RPM so if your high idle is above that it's not the a/c idle up feature anyway.

sweedespeed1 · Post by **sweedespeed1** » 18 Feb 2019, 11:33

Thanks for input. So, probably not AC then. I'll unplug it anyways and see what happens

Any other ideas? Replaced IAC, new O2 sensor. Runs pretty good otherwise. Was having a cold start problem. It threw a bad EGR code, so I blocked that off and unplugged the sensor and it seems to have fixed that problem.

93Regina · Post by **93Regina** » 20 Feb 2019, 14:44

sweedespeed1 wrote: ↑17 Feb 2019, 12:141992 240 with a high idle once warm

Disconnect wiring plug from IAC, and report back your findings