Just started this past week, my wife tells me that the AC light on the AC switch was blinking. She cycled it and it seemed OK. But this morning it stalled when putting it in drive and the AC was on. I noticed no fan(s) were running and the idle was dead slow (not in high idle to compensate for the AC load. When the engine gets hot enough to call for cooling, both fans kick in at high speed and the engine idle increases and the AC compressor kicks in. Took out my volt-ohm meter and started checking. All fuses are OK, all three fan relays are good. I can bypass the relay contacts with a jumper and the fans turn on but the idle does not. The problem is there is no voltage to operate the relay coils when the AC turned on. With air flow over the AC condenser, the AC will not work until you drive it. Obvious. This morning with a cold engine, the engine started with the AC on and it all worked OK. Perhaps the engine temp sensor had the idle up sp it worked OK. My wife went off to work so I'll wont know until tonight that the problem is still there with a warm engine. Well, tonight I started the warm engine with the AC on and the fans did no trun nor a high idle. I turned off the engine after a minute and restarted it a few minutes later. The fan turned on and a few second later both fans started up and the idle was up on the the start. I turned off the engine and removed the engine cover. I poked around looking for any thing lose or broken. Nothing turned up. I restarted the engine and the idle and fans operate normally when switching the AC off and on. At first the right fan turns on then the hot engie calls ofr colling and both fans switch to high speed. Turn off the AC and the fans trun to low speed. This is nowe an intermitten problem and not sure if it is the idle control valve. By the way, where is it on the V6. I looked up the part and it about $206 and the picture of it I cannot find it on the engine. Here is a site I found with good info on Toyota Idle speed control but it give no clue as where it sit o what type in my 2003 V6 Higlander http://www.autoshop101.com/forms/h26.pdf
No idle change with A/C on. Could it be a Idle Air Speed valve. on 2003 Toyota Highlander
by WorthFlorida in Lake Worth, FL on July 06, 2009
ANSWER by Bret Bodas , September 16, 2009
Hello, did you end up finding out the problem? Was it the idle control valve? Thanks!