Do I Have R12 Or R134?

[Gumart1]

Purchased the '91 this year and AC has always blown warm air. No codes stored with AC test.

Former owner had it to Lexus in 8/01 and had dye run through system as well as 3 cans of R12. Owner brought the car back and Tech replaced leaking O-ring seals at the expansion valve. Rechecked and everything OK.

3 weeks later warm air. Lexus says Evaporator is OK but found leak at high and low side AC lines. Replaced both hoses, charged system and added dye. No other leaks found. Parts replaced were: discharge hose, suction hose, O-ring kit (same part# replaced a month before), and bulb. Also on the receipt are 4 cans or R134.

1 year later in 2002 the car was brought to a Union 76 Station where they noted under safety recommendations: "AC Compressor (seized), also expansion valve, receiver drier, complete system flush and oil charge & recharge".

Coming into this forum I knew almost nothing. Yet I have been able to fix and replace almost everything that is mentioned on the forum as long as there is a tutorial or discussion. I have no background in AC and truthfully can't even locate most of these parts. I'd love to troubleshoot myself but don't know where to begin. I'm assuming Lexus converted to R134 but I never found the word "conversion" nor do I know how to check. The fan speeds work great as does my heater and LCD display. Any advice would be enormously appreciated.

[monarch]

You could start buy buying a Haynes manual on auto air conditioning like this: http://cgi.ebay.com/ebaymotors/New-Haynes-...sspagenameZWD1V

Your local library might also carry an auto air conditioning manual ot two. Try to get an older one that covers R12 systems and one that covers conversions to R134a too. The '90-'92 LS400's came from the factory with R12.

After you learn the general principles of auto air conditioning, you should learn about Toyota specific air conditioning systems. This involves reading the Toyota / Lexus factory manual that covers air conditioning repair and (if possible) reading Toyota technician training manuals about air conditioning and about conversions to R134a. The latter are sometimes, though rarely, available on ebay. Toyota, as usual, has its own way of doing things.

Out there in Illinois where Japanese cars still aren't that common (in rural towns) or respected, few people in the air conditioning business know much about the "toyota way" of servicing air conditioning systems and some of the ones that do could care less about abiding by Toyotas directions. Factor in widespread dishonesty in the auto air conditioning business and it could be a long, potentially expensive uphill battle to get your system working again.

For example, the Union 76 Station that claimed your compressor was seized may not realize that if the system pressure gets too low due to a refrigerant leak, a low pressure detection switch prevents the magnetic clutch on the compressor from activating the compressor. So one of your first tasks is to determine if the compressor is actually sized or not. Seizure is rare unless a big, massive refrigerant leak causes all the compressor oil to leak out (the oil is mixed with and circulates with the refrigerant). Usually on a high mileage Toyota like yours its the magnetic clutch itself (which is bolted onto the compressor) that is seized and it can be removed from the compressor and replaced without removing the compressor from the car (if there is sufficient working space). But in that case you run into the dishonesty factor again where an AC shop may tell you the whole compressor is bad or that they refuse to just replace the magnetic clutch.

So I guess you'll have to do alot of reading and research and then get multiple opinions from local AC shops. If it turned out that just the magnetic clutch was bad, then after replacing it, you would just need to draw a deep vacuum on the system for 30 minutes using a vacuum pump to remove system moisture, then charge about 3 cans of R134a into the system (charge the R134a into the vacuum). Before vacuuming, the receiver-drier (contains dessicant) would also need to be replaced, but only if the system was totally empty of R134a (had no residual pressure at all).

If the system had been properly converted in the past from R12 to R134a, then the system should now have R134a specific fittings for adding refrigerant and the sight glass on the receiver-drier should be blacked out with black paint and a sticker of some kind should have been glued somewhere under the hood identifying the fact that the system was converted.

[LScott400]

A system that has been inoperative for 4 years+ and was diagnosed as needing major components is probably not where you should begin your A/C education. Unfortunately, A/C diagnosis does not lend itself to visual and mechanical inspection. I would strongly recommend a serious contemplation of what you would be willing to pay to have properly operating A/C in this vehicle and then have the dealership diagnose and (should you decide) restore the system. Having them do the diagnosis and repair will give you the basis for warranty should there be problems in the future rather than the possibility of multiple outlays of funds which may or may not end in satisfactory results.

[93ls400walt]

Another area to look at could be the water valve. Located on the fire wall behind the throttle cable cover. Make sure that the lever moves when changing from MAX hot to MAX cold. And that you feel the air temp from the vents to corrospond. The part will have heater hoses going in and out. With a cable attached to the side and connecting to the lever arm. You can unsnap the cable and move the are by hand. And check the vent air temp also.

The manual states to Adj.

1. Remove control cable. Disconnect the clip and cable from the water valve

2. SET AIR TEMP TO MAX COOL

a. turn ignition switch On.

b. set the blower switch On.

c. set the Temp. switch to MAX COOL

3. set the water valve lever to the max cool position. eg. feel the vent air temp. Then reinstall the cable and lock the clamp