Seized A/C compressor and High idle
 

I have a 1986 190E 2.3-16 with 110,000 miles. After completing a 50 mile trip last Friday, I parked in a local store for a few minutes. When I came out and started my car, it bucked once and fired-up followed by smoke and a loud screeching noise. I immediately turned the ignition off, and popped open the hood. There was smoke coming from the A/C pulley and drive belt.

I crawled under the front of the car and unplugged the a/c compressor from the side connection, and this disengaged the a/c magnetic clutch. I re-started the engine but I noticed my idle speed to be at 1500 rpm. A friend of mine suggested that I remove the main battery connection which will re-boot the main computer. So I did just that. Idle speed dropped to 1200 rpm, which is better than 1500 rpm but still not normal. How do I drop the idle speed back to normal? Thank you in advance!

Bernie
1986 190E 2.3-16
Euro Headlights with clear blinkers
Bilstein Sports
400E front sway bar
K&N air filter
Jacob's Omni Ignition

What position is the Climate control in?
 

Greetings Bernie,

I am stabbing at your problem as I have an '86 300E and so far it seems to run flawless after the water pump change and the idler pulley shock change. I would almost think that the ACC thinks the a/c compressor should be operating if that's where you left the controls before shutting off the engine. I would also image that there is still pressure in the freon line causing the higher RPM while the engine still thinks the compressor is engaged. All in all I think I would fix the initial problem of the compressor screaming at you. Could it be any of the following problems that have contributed to this locking up of your compressor? Has it been serviced lately and they forgot to install oil along with the freon, common cause of lock-up? Is the belt loose or frayed where grip might be the problem? I've also seen compressor head pressures to excessive to restart the compressor as well, generally in hot temps though. I'd also try reconnecting the plug to the a/c with the ACC in econo mode only, to disengage the clutch and bring freon pressure back down to a non-operational level. If all else fails and you just want to make it throught the Winter, then remove the belt that operates the compressor or pull the wire off the freon pressure switch.

Charles

I drove it to Orlando, FL and NJ last July 2001 and the a/c was fine. The a/c died on me maybe a couple of months ago. It might have sprung a freon leak some where. And since fall was setting in, I just decided to for go on the a/c repair until after winter. The setting remained in "economy" mode ever since. The belt tension was good and had never slipped before this event. I suspect that the a/c magnetic clutch was engaged even without freon, and even with my setting in "econo". This probably led to the compressors demise. I need to investigate further the cause of this so when I change the compressor this spring that it doesn't happen again.

My current concern right now is how to lower my idle setting. My car has been a Florida car all its life. A current job opportunity brought me to NJ. Is it possible that the cold weather is causing this idle problem? I also noted that exhaust is soothy black. I am using a K&N air filer which is clean. I always use premium fuel every fill up, and a fuel injection cleaner once a month. It was never like this back in FL.

Bernie
1986 190E 2.3-16
Euro Headlights with clear blinkers
Bilstein Sports
400E front sway bar
K&N air filter
Jacob's Omni Ignition

chevys ned the ground leg of the plug on the compressor. your benz may also

by the way the need isn't for the compressor alone..it affects the idle speed.