Top Gear Philippines

I have a honda VTEC 97. When I turn on the air-con, my rpm goes down. I already changed it with a new IACV (idle air control valve) but it still goes down. I cleaned all the throttle body and it still goes down. What do you think is the problem with this car?

-- othik (From the Top Gear Philippines online forum)

If you don't have a check engine warning light on, have the air con system checked. It may be possible that the A/C compressor is presenting a load to the engine that the engine can't compensate enough for at idle. I also recommend checking the electrical system for its integrity, particularly the charging system.

It is also possible that the alternator may not be producing enough electricity to keep up with the engine's demands. Remember the aircon system particularly the compressor, condenser fan motor and interior fan motor combined need quite a bit of electricity.

Finally, if you had the throttle body cleaned and they removed the TPS (throttle position sensor), they might not have set it properly when they reinstalled it. It should give a reading of about 0.5 volts with the ignition on but engine off, when measured with a voltmeter.

Ferman Lao
Technical Editor
Wearing the hats of a race car driver, driving instructor, grease monkey, tuner, dyno operator, auto shop owner, motoring journalist and CAGI president at one time or another, or all at once, deep down he's just another guy who loves cars.
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