XYZLexus1

I have a 2001 Lexus GS 300. When first starting for the day will blow warm air for about 5-10 minutes. Then blows ice cold and works perfect rest of day. It was sporadic but becoming very common. My refrigerant charge is fine 48 psi low side / 220 high side at idle. When blowing cold I marked all damper actuators positions, 1 on driver side and three on passenger side and they are in the same position when blows warm on start up. Usually AC will work great after first warm blow when first starting but if car sits for 8 hours may blow warm again for 5-10 minutes. Pulled codes 42,43 from HVAC display but again actuators modulate as they should and work perfect. Does anyone have any clue? When blowing warm compressor is running! but no cold air.

Thanks in advance

sbagdon

Google says:

41 ....................... Air Mix Door Servomotor Circuit
42 ..................... Air Inlet Door Servomotor Circuit
43 .................... Air Outlet Door Servomotor Circuit

That help any?

XYZLexus1

Thanks but it none of the above. I stroked each actuator from hot to cold, floor to defrost and marked each one. When it was blowing ice cold (37.8F) i marked dampers, when blows hot at start up dampers are in same position. Its alway had an ice cold AC.

shwalker07

When you first start the Lexus with the a/c on feel by touch the the low side a/c hose. The low side should get cold very fast and if it does then your problem most likely lies within the actuators or could be a electrical issue. If that low side does not get cold right away then you have other issues that need be diagnosed but this quick test is a good starting point.

XYZLexus1

low side doesn't get cold. Tomorrow morning i plan to throw my gauges on it and see what the pressures are, that being said it will probably blow cold.

XYZLexus1

I pretty sure my expansion valve is either acting slow or not full stroking. I hit it with some freezing air and it simulated my condition exactly I then hit with a lighter and it worked. Next time it does it I will cook it and if it immediately cools I know that what it is and replace it. Pretty simple job. One thing I also notice is I don't hear the sounds or gurgling of a AC system, when messing with the cold and heat I heard it.

sbagdon

By what measurable or definition...?! : )

I did an expansion valve on an '85 MR2, and it was a bear... had to rip out the right side of the dash, to pull the entire evaporator box, rip that apart, then pull the expansion valve, and put it all back together. It was not a simple job. ; )

XYZLexus1

On a 2001 Lexus GS300 pretty simple. It is located inside the car on the driver side above the gas pedal. Somebody posted a You Tube video. Once you scrape the black insulating tape off it there is two allenhead screws and it slides out. Obviously you still have to deinventory the system and recharge which is simple. Now that I modulated it is working perfect so we shall see. I have no doubt if I had taken it somewhere it would be a new dryer, evaporator and $1,500 worth of bs vs $30 expansion valve, $11 in Freon, and a free vacuum pump rental from Autozone......

sbagdon

Watched the video for an '02 GS430... It makes a lot of sense, yet geez, they really hid it up there...! Yet thanks for the breadcrumbs...!

XYZLexus1

Did the job last night. It was PIA but doable. I suggest loosening the bolt on the engine side of the hose mount. This may give you some wiggle room to get the expansion valve in and out easier since everything is hard piped. I got it out but getting it back in and getting it to line up was a PIA, used a hammer handle to push it around. My old O-Rings were like new and flawless, was a waste of time changing. In the end it appears my problem is solved, AC working perfect. Total cost was $39. Replaced expansion valve and pulled vacuum and charged (just under two cans). Old expansion valve had some black residue which was probably leading it to stick.

XYZLexus1

Strike two. AC actuators were good and so was the expansion valve as I still have problem, lol. Finally got gauges hooked up while it was blowing hot. Low side pressure 80 psig high side 110 psig. static pressure is 110 psig. Confirmed clutch is not slipping, pushed broom stick against it while running and zero change in gauge reading, broom stick did get cut though, lol. Usually a bad clutch blows cold then gets warm so mine was opposite but i had to try something. Soooo it appears it may be the compressor. Funny thing I can spin the compressor by hand with zero resistance, almost like an alternator. On my 4 runner and truck it takes a lot more force to turn over the compressor. Again when it works it works perfect. I even hit expansion valve with liquid nitrogen (turned dust blower can upside down) to make cold and close and still zero compressor resistance when turning. I have no idea how a compressor can go from good to bad. Next step is replace compressor.

sbagdon

Intermittent issues are the worst. At that point, you just suck it up, install the $400 parts, and move on...

XYZLexus1

Ordered compressor and condenser. Denso parts which are supposed to be supplier to Lexus. Compressor was $265 and Condenser $116. We shall see. Probably get away with using old condenser and changing drier desiccant but hey when you do work yourself your already saving $$$$ so I splurged on new condenser, lol. Update to follow.

XYZLexus1

I think i got it on the run. Found out my compressor has a control valve (saw on new compressor i received). It modulates suction pressure. BINGO that is my issue. Its probably gummed up. Anyway it cost $24. Compressor works to good when working. Most compressors with control valves are variable vane and have an electrical connection, that what threw me since mine is piston with wobble plate which usually do not have the ability to vary loads. What pushed me to it was the new compressor has no resistance either when I rotated it and my discharge pressure is dead on at 225 at idle (when working) anyway will deinventory and install and pay shipping to return compressor and condenser lol.

XYZLexus1

SUCCESS!!! The control valve resolved the issue. Accessed from under the car after removing splash shield. Working perfect. Pretty simple much easier than expansion valve. remove splash shield, then a little vertical shied, deinventory, remove snap ring holding valve in compressor, grab with vice grips rotate and pull out. reinstall new, pull vacuum charge done. total cost $32 including freon. VCR120 CONTROL VALVE Denso 7SB16/ 7SB16H/ 7SBU16H/ 7SBU16 for Lexus GS300 off ebay for $22. To summarize problem was AC would not blow cold at times, other times it would work perfect. Revving engine while not cooling would get it to cool.