billbranch Posted July 15, 2006 Report Share Posted July 15, 2006 Hi, Everybody, I've owned the car for almost three years, and if I engage the AC while idling, the engine almost stalls, and the CHECK ENGINE light flashes. While driving, when the compressor cycles on, the car jolts severely. I just installed a new compressor, new receiver/drier, new expansion valve. Same symptoms. Today, I had the condenser and the evaporator core flushed out. Same symptoms, but the system works so well 9°F, now it won't cycle off. I have to turn on the heat to thaw out the HVAC system. We did test last year, and it seems the CHECK ENGINE light syndrome may be electrical in nature, but can't figure out why. Questions: 1.) Has anyone else experienced the teeth-rattling jolt when the AC compressor kicks on? 2.) Any theories as to why the system won't turn off? Thank you. Quote Link to comment Share on other sites More sharing options...
Guest broke Posted July 15, 2006 Report Share Posted July 15, 2006 Hi, Everybody, I've owned the car for almost three years, and if I engage the AC while idling, the engine almost stalls, and the CHECK ENGINE light flashes. While driving, when the compressor cycles on, the car jolts severely. I just installed a new compressor, new receiver/drier, new expansion valve. Same symptoms. Today, I had the condenser and the evaporator core flushed out. Same symptoms, but the system works so well 9°F, now it won't cycle off. I have to turn on the heat to thaw out the HVAC system. We did test last year, and it seems the CHECK ENGINE light syndrome may be electrical in nature, but can't figure out why. Questions: 1.) Has anyone else experienced the teeth-rattling jolt when the AC compressor kicks on? 2.) Any theories as to why the system won't turn off? Thank you. On my 505 there is an A/C idler compensator or selonoid on thr throttle body. When the a/c is actvated the compensator lets in more air and increases the RPM. Quote Link to comment Share on other sites More sharing options...
billbranch Posted July 15, 2006 Author Report Share Posted July 15, 2006 On my 505 there is an A/C idler compensator or selonoid on thr throttle body. When the a/c is actvated the compensator lets in more air and increases the RPM. Hey, Broke, there's a similar device on the 405's, and mine is working. I am not talking a decrease in the idle speed: I am talking about the car (seemingly) turning itself off for a split second! If I am accelerating hard, and the AC compressor cycles on or off, it's as if my foot falls off the gas, not smoothly, mind you, as I said, it's a jolt. Now, of course, the plot thickens. The AC now (and maybe it did it before; I just never used it) when it's stuck on with the switch on, and I turn off the car, it's as if the key is still on: the radio's playing, the IP warning red lights are on, the engine is off. I think I am going to pull the error codes. Maybe these electrical events are related. Last year we discovered that, when the clutch engaged, it seemed to draw too much current. Bill Quote Link to comment Share on other sites More sharing options...
billbranch Posted October 22, 2008 Author Report Share Posted October 22, 2008 We knew it was electrical in nature, so, while we were checking the workshop electricals we discovered that the AC circuit is tied into the Motronic ECU. We swapped the ECU and problem solved. Amazing. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.