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LIght comes on on dashboard under RPM's. Is a car with something coming off back
Problem for Lexus 1999 RX 300
My ac is draining battery
Clarification Request
Posted by Chemist1961 on Nov 01, 2009
The ac does not run on the battery, but when running will cause additional load on the alternator which in turn also charges your battery. So you more likely have either a defective battery if over 5 years of age, or a failing alternator, in which case when under heavy load (with a.c. running) the problem becomes more evident. You can have your battery and alternator and charging system checked with the vehicle running by a good service center, or an alternator rebuilder/ automotive electrical repair specialist. There are alternator rebuilding companies who can test both and tell you what you need and generally fix you up for less than if they sell the parts to a service center who in turn mark them up again and sell to you. I removed and replaced the alternator on my 2001 RX myself, had it tested and rebuilt with warranty for under $150, but there are a few tight spots to get to on the RX300 unless you are patient. You might also start by inspecting and cleaning battery terminals and connections.
Best Solution
posted on Nov 01, 2009
The battery does not power the a.c. system of the car.
You more likely have a defect in your charging system, either an aging battery beyond 5 years, bad battery connections which are corroding or failing alternator.
The ac runs not on the battery, but on the alternator output, so if the charging system is beginning to fail with the ac on creating extra load the problem becomes more evident.
You can have your battery and alternator tested with the car running, then decide if you want to attempt repairs. I had my RX300 unit tested and redone with warranty for under $150 and reinstalled myself although the space is tight
An alternator rebuild shop will generally overhaul and reinstall the unit if required and save you extra $.
This is not your corner garage and few mechanics will do this work themselves so going straight to a reputable electrical specialist will often be the best method if you chose to have it tested and or rebuilt.
You more likely have a defect in your charging system, either an aging battery beyond 5 years, bad battery connections which are corroding or failing alternator.
The ac runs not on the battery, but on the alternator output, so if the charging system is beginning to fail with the ac on creating extra load the problem becomes more evident.
You can have your battery and alternator tested with the car running, then decide if you want to attempt repairs. I had my RX300 unit tested and redone with warranty for under $150 and reinstalled myself although the space is tight
An alternator rebuild shop will generally overhaul and reinstall the unit if required and save you extra $.
This is not your corner garage and few mechanics will do this work themselves so going straight to a reputable electrical specialist will often be the best method if you chose to have it tested and or rebuilt.
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