Help! - 99 LX - A/C Suddenly blowing hot

[arbetrader]

A/C was blowing nice and cold however over the past couple months every now and then it would suddenly switch to blowing hot, but then just as fast as that happened, it switched back to cold again...

Fast forward a few months now it's only blowing HOT, and I mean as if the temp was set to the hottest setting. I hear NOTHING when I switch the a/c on and off (no compresser sound) - ** The Rear A/C still blows cold

Any ideas? Compressor?

I once heard someone mention something about a coolant temp sensor on the block can sometimes be culprit... Any ideas? If so, where would I Find that? where should I start?

 

[parnoren]

The compressor should be ok if you get cold air in the rear A/C as there is only one compressor. And if the rear A/C blows cold, then I don't believe you have a leak as both front and rear are on the same tubing system. I just had a leak in the lines going to the rear and I had no A/C anywhere. After the repair I have cold air everywhere. Hopefully somebody with better knowledge can chime in on the temp sensor.

 

[TwiceWithHair]

I've had my car for a couple years. Just assumed my rear air worked. My passengers were upset to find out that it didn't. As was I. I'm in the same boat as OP, but my front works great and my rear seems to just blow air. Not cold air.

 

[arbetrader]

I thought for sure there would be a separate compresser for the rear a/c as when I turn that on and off I hear a sound in the back similar to the a/c compresser each time I turn it on, and it's coming from the rear... I know in the toyota siennas (04-?) they have separate compressors as I was selling Toyotas back in 2001-07 and that was part of the product training. I thought for sure Lexus would have done the same thing...

Anyway, does anyone know anything about the coolant temp sensor or would that have nothing to do why the symptoms?

 

[OursSauvage]

One compressor but two cooler unit.

First, I would check if the cold/hot mixing flap is working (into the dashboard)
Do you ear them moving when changing temperature?

If you put fan an output direction on "Auto", what happens?
does the exit place change from time to time?
does the fan speed goes down if you increase the Temp?

 

[arbetrader]

One compressor but two cooler unit.

First, I would check if the cold/hot mixing flap is working (into the dashboard)
Do you ear them moving when changing temperature?

If you put fan an output direction on "Auto", what happens?
does the exit place change from time to time?
does the fan speed goes down if you increase the Temp?

I do not really hear a difference when switching from cold/hot which is strange. I can't hear the a/c compressor switching on/off either - BUT the rear a/c is blowing cold so that tells me the compressor is actually working.

STRANGE THING: At the time this all happened I also noticed that my outside temperature gauge completely disappeared - in other words, it shows nada, nothing. It's totally gone - which is strange... Thoughts?

 

[arbetrader]

Well... Took a 180 mile drive on Thursday through 93 degree heat without A/C with the windows open the whole time - lol, the kids were whining!

Anyway, about 5 miles from our destination I noticed the outside temp gauge mysteriously turned on and was working, so I thought I'd turn on the a/c to see if that magically turned on... IT DID!!

But it only lasted about 5 mins and then the outside temp gauge disappeared again, and voila - back to blowing hot air!

The following day I investigated by pulling off the front panel of the climate control console and "somehow" a connector was very loose and popped off as I was pulling it toward me. Reconnected, and back to cold a/c and fully functioning outdoor temp gauge. I'll bet when I had my console off previously when doing some stereo work it had disconnected.

I love simple fixes