A/c Advice

[LexusLooker]

OK guys, I confess, I drove a BMW 545 and fell in lust. I did not have s*x with that car. But my LS got jealous. Instead of a cold shoulder, I get warm air. On warm days, the A/C just doesn't feel cold enough at initial cooldown. It's actually been that way the 2 years I've had it, but it's worse now. It's not low on freon, the fans work, the coolant / engine temp is fine, the heater valve is closed. So while I had it at the dealer for a tire balance (because they do it so well...don't give me too much grief), I had them check the A/C. As I suspected from some research I did, it's something akin to a broken heart: the expansion valve. According to them, they say I need to replace the evaporator too. I don't buy that part of it. Are any of you guys A/C nut heads? I'm sure I can get it fixed just as well elsewhere for less money, but I'm not convinced that I need an evaporator. Thanks in advance!!!

[RFeldes]

While it is probably true your evaporator is okay since you have no leak I would be inclined to replace it since they are going to be in there anyway to change the expansion valve. There is a fair amount of labor to get to both and you would kick yourself if you had to go back in later. Depends on how long you want to keep the car.

[spr97ls]

Did they check for leaks? The only way the evaporator needs to be replaced is if it is leaking, so I'm not sure why they would say that. Evaporators typically don't go bad, and they are very expensive. Anyway, the expansion valve itself is an inexpensive part (probably $75 or less), so I would just have them replace that part and recharge the system. I would get a second opinion at a shop that only works on automotive a/c system. And remember, any time the a/c system is open you need a new receiver/drier (which is also an inexpensive part). Let me know if you have any other questions.

Greg

[LexusLooker]

Thanks for the advice, guys. I was pretty sure that an evaporator either works or it leaks. They don't have any moving parts that break. I just needed confirmation of that, so I appreciate the info. My original post was based on what the service writer said, which implied that the evaporator was "broken" - whatever he thinks that means. However, the paperwork that came out later said that there was a small leak in the evap, and they added some 134. It would have to be an awfully small leak since a) they added less than a pound (or whatever size they use now) after 9 years of use and B.) I didn't see any bubbles in the sight glass after running awhile. So I guess it all has to be replaced anyway. Thanks for the info on the receiver/dryer by the way, and on the A/C-only guys. Which leaves me 2 questions:

- Should I get it fixed soon, even though it's working fairly well and will probably last a couple of summers, or can it wait? The service guy was hinting that not doing something soon could possibly lead to "black death". He really said that. It's my understanding that if a compressor goes, you can distribute all sorts of nasty stuff throughout the system and have to replace even more parts. I guess that's black death. But a evaporator leaking and a sticking expansion valve should only cause hot air, right? Unless the sticking valve is putting a strain on the compressor somehow? We sure don't want to encouage black death, do we!

- Has anybody DIY this on an LS? I've replaced compressors, receiver/dryers, expansion valves, heater cores and hoses back in the old R-12 days, so I know enough to be dangerous. Could be a fun task to have the LS dash spread out all over. However, I'd still have to have somebody evacuate and charge it. <ok...I did a search after posting this...it can be done but you should have a shop manual / access to TIS>

And now, slightly off topic: I had an old 1966 Cadillac limo with rear air. The air wasn't working, and it was an amazing Rube Goldberg system of wires and vacuum lines. To turn it on, you flipped a switch which opened a vacuum valve which sucked a relay closed. I couldn't figure out why the switch wasn't an electrical one that made the connection in the first place, instead of going through a vacuum circuit. I guess you had to put vaccum on the system at some point anyway, so that's a good place. Then, controlling the temp was a kick. When you set the temperature dial, a series of resistors measured cabin temp and heat load on the car and controlled how much current passed through a hair-thin wire. As that wire heated and cooled depending on current, it opened or closed a diaphram which routed air doors for more cool or more heat. After a few beers, I figured out how the whole mess worked and fixed it. The ducts for the rear air went from the evaporator in the trunk, up through the rear pillars and partway across the roof to blow air out of ceiling ducts. After the A/C was running awhile, it was so cold that the exterior sheet metal would get condensation on it in the path of the ducts. Ahh, the good old days of big compressors and R-12!

[RFeldes]

It has been my experience and my mechanic's that replacing the expansion valve in a timely manner does not call for an evac. Just a re-charge. The only Black Death is that Black Smoke he's blowing up your . Removing the glove box to get to it is a pain but you should be able to do it with the manual or someone shooting you a pdf file. If it is working now I wouldn't worry about it or a least get another opinion. He had to be able to get to it in order to detect a leak and I would doubt he could even with a sniffer. The only way would be to put a leak detector in and see if it shows up coming out the drain.

LOL those old Caddies could blow some cold air!!!

[wwest]

How do you know the refrigernat is full...??

The only way I know to check easily is to see how fast the sight glass/guage transitions from CLEAR to bubbles and then back to CLEAR again because the flow becomes full LIQUID refrigerant.

Be sure the car has sat running for a long time with the A/C off and then have someone activate the A/C while you watch the sight glass. Before the compressor kicks in the sight glass should be clear and then witin seconds of the compressor engaging you should see bubbles moving through the sight glass tube. Then within a very short time, 2-3 seconds, you should have a solid liquid flow with no bubbles if the system has enough refrigernat. Absent a dye in the refrigernat it is practically impossible to tell the difference between no flow at all and liquid flow so watching the transition period, empty-bubbles-liquid, is the only way to tell.

If the refrierant is TOO low the compressor will not engage at all to protect it.