92 Ls400 Ac Blowing Hot Air

pierce1 · June 9, 2008

:( Summer of 2006 or 07 my ac started blowing hot air, I took it to a dealership (not lexus) they found my freon had leaked out, they did the dye test a hose was leaking. I ordered the hose and they replaced it did a conversion to 134R freon. Today it started blowing hot air. I did the ac test and 00 were showing. Also it has been ac oil a little bit. Could I have another hose that is leaking. I can hear the ac compressor kicking in. Any suggestions. The first repair cost me 400.00 as the hose was over 200.00 from lexus dealer. Any suggestions appreciated. :( :( :(

Alexander the o.k. · June 9, 2008

Also it has been ac oil a little bit.

Do you mean 'leaking'?

If so, how do you know? Are there spots-if so, where?

The obvious cheap 1st step would be to go to autozone or some such and buy the 134 recharge kit w/gauge so you know where levels are. Get one w/dye. Or you could try the soap bubble test. If you've lost freon you've lost oil. Make sure to get some oil into the system or the compressor may go next.

I would avoid any of the 'stop leak' additives as they are a last ditch move. At least you might be able to stay cool short term and pinpoint the leak saving ' diagnostic dollars' at Lexus as they add up PDQ.

Not that familiar w/r-12 replacements, but someone here may help w/ some other tips.

wwest · June 9, 2008

Also it has been ac oil a little bit.

Do you mean 'leaking'?

If so, how do you know? Are there spots-if so, where?

The obvious cheap 1st step would be to go to autozone or some such and buy the 134 recharge kit w/gauge so you know where levels are. Get one w/dye. If you've lost freon you've lost oil. Make sure to get some oil into the system or the compressor may go next.

I would avoid any of the 'stop leak' additives as they are a last ditch move. At least you might be able to stay cool short term and pinpoint the leak saving ' diagnostic dollars' at Lexus as they add up PDQ.

Not that familiar w/r-12 replacements, but someone here may help w/ some other tips.

Assuming the A/C compressor is actually running, is it cycling on and off as it should..??

Your LS has a dual mode refrigernat hi/lo pressure switch to prevent the A/C compressor from running and being damaged with refrigerant too low and also shuts it off once a sufficient level, "reserve", of liquid refrigerant is available on the "high" pressure side.

Also, you can check the sight glass for the existence of refrigerant. IMMEDIATELY (two person task) after A/C clutch engagement observe the sight glass for the beginning of the transition from clear gas, to liquid w/bubbles, and then to clear liquid refrigerant. After the clutch releases the reverse should happen, liquid to bubbles to clear gas and then the compressor should restart, possibly with some delay.

As someone cycles the temperature setpoint between max heat and max cool watch and observe that the HOT water flow control valve in the engine compartment at roughly the top center of the firewall moves smoothly between fully closed to fully open. This valve is operated by the remix/reheat vane/door servomotor inside the dash/plenum area via a push/pull cable. If the water valve is stuck (it happens), say in the fully open position, the system will always be in max heat mode.

Do you get cooling before the heat coolant heats up but not after..??

Once you get the system back working you may want to slip the push/pull cable off of the valve and wire tie it into the fully closed position. That will result in your A/C being dramatically more efficient, observeable/measureable FE improvement, during the summer months. But remember to reverse the procedure come fall. Put the cable back on the valve but open the A/C clutch compressor circuit.

VBdenny · June 11, 2008

If you've lost freon you've lost oil.

Well, maybe, maybe not. Most slow leaks do not lose much oil and adding too much to your system can reduce your cooling. I would just put a stick thermometer in a vent and add a couple cans of R-134a. The compressor should stay on all the time when set to max. When the temp until it gets to around 50 or so.