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Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8579
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Mitsubishi: i have a mitsubishi that when the car is turned

Customer Question

i have a mitsubishi that when the car is turned off. the air conditioner keeks running n also the head lights stay on
Submitted: 2 years ago.
Category: Mitsubishi
Expert:  George H. replied 2 years ago.
Hello I will help you with your question,
What year and model is your car?
Expert:  Doug replied 2 years ago.
Hi,
When you experience the AC sticking on and the headlights no longer turning off on these cars you are going to be dealing with a bad AC magnetic clutch relay. This is a very inexpensive fix and can be done yourself for most people.
The problem Mitsubishi has with these clutch relays is that they short laterally, causing the load circuit to bridge to the coil circuit. When this happens, it trickles a back feed of voltage through the vehicle back to the AC ecu. This spreads to the AC main relay, causing just enough current to "latch" the relay... it is not enough to engage it on its own, but when the relay engages naturally when the key is turned on, the short in the magnetic clutch relay is sufficient to prevent it from releasing when the key turns off.
This results in further bleeding of voltage backward through the AC main relay, causing the front ecu to partially allow the lamps on, and then it gets worse from there depending on the amount of continuity in the short.
As for the fix... it is as simple as getting a new relay.
Go under the hood and you will see two relay panels, a large one with fuses in it and then a small one right next to it with just a row of relays. Remove the covers from both, then look at the narrow box relays. You will see the rear-most one (nearest the windshield) is marked in the cover with a snowflake. This is the clutch relay. Take a marker or touch up paint and mark the relay so you don't get it mixed up (if you put it in another location it can cause worse symptoms).
Pull the relay out and set it aside. Go to the main relay panel and locate the horn relay marked with the picture of a trumpet, then remove it and put it in place of the magnetic clutch relay.
Cycle the key on/off a few times and you should find your problem resolved.
You can then move the horn relay back to its original location (just use it for testing), and then take the bad relay you marked to the auto parts store to have them match it up, or go to a Mitsubishi dealership where they should keep this in stock (it is REALLY common), they are about $12 from Mitsubishi usually.
If you need further help with this or you find something beyond what I'm anticipating just let me know and we can dig deeper. This relay is pretty much always the cause of this behavior though.