llcoolpass

how much R134 did the system take... I suspect not enough... if his source wasn't losing any, then sure, compressor might be the general source of the problem, but if it took 2 cans, and nothing left in them [nothing appreciable] then it's obviously working.... I love working on car a/c systems ... physics is my life.... but you're no where near me. otherwise, id tell you to come by and i'd help you . but respond to the appropriate stuff and ill g et back to you

mmatheny

Behind the glove box.

mmatheny

Well, a very important part of troubleshooting this is knowing what BOTH gauges read. If both were zero, then yes, bad compressor. But without knowing what the high side read, we are only offering an educated guess.

GEORGE_JET

Actually if both were at zero, that would be a leak. With compressor off, the at rest pressure will be around 70psi. Just got done working on the wifes car, running I charged it to 35psi low side, app 180 psi high side, 45 deg air at the vents, ambient is high 80's.

From the information availible, it sounds like the expansion valve is bad, there is strong evidence that the compressor is at least partially functional. But we must have both hi and low readings, while running, to give proper diagnosis.

mmatheny

Right - about 70 psi because both sides balance out after the compresser quits running. And you are correct about zero on both sides. But if low side only is zero, bad exp. valve.

llcoolpass

the cooled off, equilibrium pressure is mostly irrelevant... it's based on ambient temperature at that point. so yeah usually you're seeing it at 70 -something psi due to ambient. but it tells you that you probably have a substancial amount of r134a gas in there, but if too little or too much you won't know with that alone

lexus72

UPDATE:

Ok, so here is a quick recap of my issues and an update. Basically, for two years my '94 es300 has had an intermittent working AC - starts cold, then about 10 minutes later is blowing warm. After researching the forums, it seems that most '92 - '96 models eventually suffer from a bad expansion valve over time. I purchased a new OEM expansion valve and receiver drier - received many quotes from $65 to $350 to replace these and recharge the system.

Brought the car to a non lexus minded mechanic, and prior to swapping any parts on the car, he diagnosed the car with at least a bad compressor (although he said it was possible that the expansion valve could be faulty in addition, he felt strong that the main issue was the compressor). He surmised this from a low pressure reading on the low side (was zero and becoming negative). However, because I have had even some COLD AC in cooler spring temperatures, I didn't agree with him that it was the compressor. My feeling is that I shouldn't have any cold ac if it’s the compressor. (as you will read, I was right that it wasn't the compressor)

I then put out another add on craigslist (specifically looking for a Lexus minded mechanic). I found a guy locally that only works on lexus/toyota vehicles - and personally owns a 2000 es300 and 2004 es300 and has almost totally taken apart a '93 es300 in the past. When I arrived at his place, he had in fact just changed out his expansion valve, drier, compressor, condenser, evaporator in his 2000 es300 and was putting the lower dash back in place. His symptoms were exactly the same as mine and he new it was the expansion valve that was faulty but had a good point:

"Although the expansion valve is the culprit for the intermittent AC - most likely this stems from a failing/deteriorating COMPRESSOR. The internals of the compressor wear out over time (14 year old compressor) and begin to fall apart in small bits. These small bits begin to find there way to the expansion valve (blocking the spring) and clogging the evaporator, drier....etc" Although he agreed that my compressor was currently working (but most likely deteriorating inside), he pointed out that it just makes sense to replace the compressor NOW since more internal deterioration would just block the new expansion valve with time - thus ending up right where I started with a blocked expansion valve or system.

Solution: 1. He found a $30 used compressor for me from a low mileage '96 es300 (the compressor works well and there does not appear to be any internal deterioration). He changed that out first and - - - no cold AC. I tell you this so that we can all agree that my initial problem is in fact the bad expansion valve and NOT a compressor! 2. He replaced the expansion valve and the evaporator with new parts and cleaned out the system 4.charged the system......5. COLD COLD COLD AC!

Total spent to have a working AC, including parts and labor(all involved) came to $420. The biggest single expense was the $130 aftermarket evaporator. I would have probably spent $100 less had I simply taken the car to this guy first...but we learn from our mistakes.

Although I didn't plan on spending soooo much, I'm happy to have a working AC here in Michigan. My car only has 130,000 miles and is in excellent condition, so I think its well worth the investment. Mostly though, through this forum and discussion, it’s been a great learning lesson.

If anyone is located in Southwest MICHIGAN or Grand Rapids , I would highly recommend this mechanic and can give you info.

mmatheny

Glad to hear he agreed with us - In Texas, AC is a necessity!

llcoolpass

Yeah a good mod would be an inline filter to prevent the compressor wear debris from clogging it again.

Like i said before anyone around my parts wants me to help them on their a/c just let me know.

This guy did you right, should ask him to join this site!

Did he replace the evaporator just to avoid trapped debris in the old one from re-clogging the expansion valve? If so, why did he suspect so much debris when Lexus has admitted the expansion valve itself is just faulty[at least from what I remember]? Like you said the compressor in your car was actually working well and probably not too worn out and debris-causing.

You must enjoy the cold all year long ......[Michigan]

mmatheny

I thought the drier would trap most of the debris (until the netting busted, then drier debris is all through the system!)

lexus72

He pushed high pressure air through the evaporator (I think in reverse) and saw lots of little bits coming out. Since the evaporator tubes get smaller and smaller, its reasonable that some bits get stuck inside. Plus, it looked pretty beat up on the outside. HE and I were on the fence about completely replacing the evaporator, or just trying to clean the old one out. The problem is that the evaporator leads back to the expansion valve and thus, the expansion valve could stick again from any little bits. ALL HYPOTHESIS though....

Who really knows what the best thing to do is. I could have kept the old compressor and evaporator and saved myself $170 in parts and another $45 in labor. But if this all failed again next year, would that have been worth the savings? I probably would be pissed about it next year... I look at it like it cost me more now, but is saving me a heart attack next year and the following year.

Yes, Michigan can be really cold, but its also HOT for about 3 months. Hot enough to long for a working AC...

lexus72

You could be very right, but my drier was probably 5 years over due for replacing. I'm sure that all that netting deterioration and the compressor internals were the little bits floating throughout the system.

mmatheny

How did the evap get beat up? I could see a condensor being beat up. Also, make sure you put a filter back in (if you have one!)

lexus72

Here is my only advice about having an expansion valve replaced. Whatever mechanic you chose, he/she should be well versed in THIS specific expansion valve issue with the es300s. Not only should they be familiar with this repeated failure within the es300 line, but they should also know exactly where the expansion valve is located. They should know that the evaporator core HAS to be removed. They should know that the expansion valve is held to the evaporator from the TOP by a nut that is NOT easily accessible unless the core is removed. They should know that the glove box has to be opened up and that even the blower may need to be removed.

Also, if your car is as old as mine - 14 years, its not unreasonable that you should be replacing the compressor with a newer one (even if it seems to be working fine) - heck, the 2001 camry and solara are the same part numbers anyway - about $85 off of ebay for a newer used one.

Having said this, in watching my mechanic do some of this work, I truly believe that this project could be considered a DIY by those with a serious mechanical background. Certainly not by just anyone though.

lexus72

I think that the previous owners didn't ever use a cabin filter. There was a ton of debris stuck to the evaporator. I imagine that year after year all that retained debris just kept kicking around at the evaporator. Like I said though, it was a 50/50 decision to replace it with an aftermarket one. I might have spent $135 needlessly. Hard to know.