A/c Problems - As Usual...

[jsweb]

Hello,

Ran across this board while searching for A/C issues with my 1992 LS400. Sounds like I'm not alone! The LCD was out when I got it 25,000 miles ago. Two weeks later, the A/C went out. The shop ran leak tests, said it was good, recharged it, and sent me on my way. Two weeks later, the A/C was gone again. This time, there were massive leaks. Interesting...

Spent $1500 to replace the compressor and recharge, only to find out that the evaporator was leaking as well. $1200 more out the window. I wouldn't have paid this much, but I was already $1500 into it, so I didn't want to blow it for nothing! Now, two weeks or so later, the A/C is still blowing sort of cold, but not as cold as it seems like it should. Does anybody know what temperature is normal for it to blow? It seems to take fifteen or twenty minutes to cool down the car now. I've replaced the major parts, and it's still blowing colder than no A/C (maybe 60°F), but I have no idea what else could be wrong!

Then, today, my climate control "auto" switch (which worked well before), now turns the fan to low automatically. The fan will work on Hi, but when switched to Auto it shuts to low no matter what temperature the car is. Any ideas?

Meanwhile, in the time I've owned it, I've had a rear main seal go out ($500), the passenger's side door lock go out ($400), the master window switch go out ($400), the brakes have begun to squeak, and there is a slight shimmy when driving freeway speeds. I notice that I have SC-400 wheels. After reading some of these posts, I think I see why.

For a car that was "in perfect condition" according to my pre-purchase inspection, this car has just been a money pit. My past experiences with older Toyotas has been excellent, so I figured this would be no different. WRONG! To be fair, though, it does have 175,000 miles and runs smooth (for now).

Thanks for any suggestions and feelings of empathy!

Johann

[VMF]

strange thing with AC, i have around 130k on mine and ac blows air so cold that even with 90-100 degrees outside it is gettin cold in 5 mins. no leaks whatsoever (knock on wood). only pulleys and water pump starting to make noise but i'm going to change them in 1-2 weeks. as to the rest of the problems i think they are unusual for an ls with that kind of mileage

[Rich Sweitzer]

Very strange about the massive AC failure on you LS-400. Did the '92 LS-400 have R-12 or R-134a, and did the shop put the same stuff back in the system? And had the system ever had problems before? Just curious . . .

A thought . . .

My '91 LS-400 (with 295,000 miles) lost its AC charge this spring and it turned out to be a failed manifold gasket on the compressor (a $5 part). It seems that age and its proximity to the exhaust manifold caused the rubber to fail. Replaced the gasket, pulled a vacuum and recharged the system (after leak testing) and all was well; except one other thing. During the recharge process I discovered that both electric fans in front of the radiator were seized. This caused the condensor to overheat and the pressures in the AC system to elevate. (That shouldn't be a problem at highway speeds though.)

If you do a lot of city driving that could be your problem. You can check the operation of the electric fans by unplugging the connector from the temperature sensor located at the inside bottom of the radiator on the driver's side of the car (drive it up on a pair of car ramps if you can, slide under the front end, drop the engine undercover, locate the sensor and then squeeze the release clip and unplug the connector from it). Then turn on the ignition and check to see if the pair of fans in front of the radiator run. If not it could be the motor(s) are bad, a fuse is blown (located in the fues block next to the battery), and/or bad fan relay(s) (there are three underneath the driver's side headlamp assembly), (Lexus acheives two-speed operation by connecting the fans in series with this arrangement for low speed). If the fans do run it could still be a fan issue because there is a pressure switch located behind the passenger side headlamp that starts the fans when the AC system's high side pressure goes above the switch's preset pressure. (You need gauges and at leas a rudimentary knowledge of AC systems to get this deep into it however).

By the way, if the fans are bad Lexus wants a whole lotta of dough for just the motors. I bought complete fan assemblies "online" for a whole lot less.

[SKperformance]

i am going to say the interior temp sensor is not functioning

as it find the interior not hot enough to need a more cooling of the fan speed

it may have fallen in the dash

it is usually located on the right side by your knee on the dash

pop the cover off and see if it is still moounted there

it uses the hvac system to suction interior air past a sensor for adjustments in fan and temp speed

have you done the self diagnostic a/c test ( try that as welll if not)

[jsweb]

VMF,

I'm thoroughly jealous...however, my A/C didn't go out until 150,000 miles...so who knows what's in store!

Rich,

It came with R-12 and got it this time as well. I bought the car at 150,000, so I'm not really sure if there were any problems before. Good idea on the fans, but my mechanic says the pressure looks good, not elevated. I'm not proficient enough to get that far into it, but I'll pass it along to my mechanic. Thanks!

Sk,

I did do the self-diagnostics, but it just came up with a code 33 with no tone, which I guess means it used to have a problem with the Air Mix Door Position Sensor Circuit or Air Mix Servomoter Circuit, but doesn't any more. No other error codes, including the ones for In-Vehicle Temperature Sensor Circuit and Ambient Temperature Sensor Circuit. Good thing it was 100° here today, so I could read my LCD display, which is blacked out except on really hot days.

I got a temperature gauge and see that the car is blowing at around 60°, when it should be at 35°-45°.

Thanks for the help, and I'll keep checking back for any other good ideas!

Johann

[VBdenny]

From my colleg days when I took an A/C course, I was told that auto A/C should blow about 30 degrees less the the outside air temperature. Anything more than that is a bonus. God help you guys in Arizona!

[jsweb]

VB,

My mechanic said something similar to that, telling me that 62° was normal. However, when I got a temperature sensor, the package said that for an ambient temperature of 75°-85°, the sensor should read about 45°. Then, I got service manuals, and they stated that the temperature should be between 35° and 45°.

Johann