Question about 1992 Lexus Sc 300
When girlfriend is driving her sc300 when she turns the a/c on the car will die. also when the a/c is off the car idles at abot 600 rpm's. what could possibly be the problem
Does the car only die at idle with the A/C on, or does it kill the engine when switched on at road speeds? Are there any belt slippage noises (Squealing sounds underhood) when switched on prior to dying? A locked compressor will kill an engine at idle, but should squeal like a stuck pig (belt slippage) if switched on at speed (with a noticeable decrease in power) and will stall the engine when the throtle is let up.
A short in the compressor clutch could kill/depress electrical power to the engine sufficiently to kill the engine, but this should also blow a fuse unless it has been bypassed to "correct" a previous fuse blowing problem.
When the A/C is switched on, there is a throttle idle position compensation to accomodate the added load of the A/C system, and if this is not functioning it could cause the engine to die at idle with the A/C on, but it should cool normally at road speed if this were the problem.
There is also a secondary radiator/condensor electric cooling fan underhood that is turned on when the A/C is on to insure enough air is moved across the condensor coils to transfer (remove) heat from the Freon coolant, and a short in this motor or circuitry could also possibly cause a similar problem, as could also the interior fan system, though this is pretty unlikely.
With the engine off, locate the compressor/clutch underhood, and determine if the center hub on the clutch rotates freely or if it feels locked. If it feels locked, have someone start the engine and engage the A/C while you observe what takes place underhood. If the compressor clutch engages (with a noticeable "clack" sound but the center hub doesn't turn, you have a seized compressor which will need to be replaced. If it does turn but the engine does die, I'd suspect one of the other faults described above.
Hope this shed some light on the problem, and good luck!
Posted on Jun 07, 2008
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Posted on Jan 02, 2017
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