What I believe is that the speed resistor that controls the of the blower motor may be faulty.
https://www.ebay.com/itm/94-LEXUS-SC...8AAOSwwPRcCwoo

 

where is this located. Is this different than the resistor itself or this supplies power to resistor to turn the motor on?

 

Disregard the upper link to the ebay because that one is for SC-300-400 and not LS 400. The one that fits your car is this one. Click the link below.

https://www.ebay.com/itm/OEM-TOYOTA-...ss!99503!US!-1

Here is the part number for yours 8716550020 on Lexuspartsnow.com its price is 250 dollars and it fits 1995 Lexus LS400. It is located next to the blower motor. Check it's pictures on eBay.

 

That is the resistor. i dont mind changing it. But my issue is, there is no power going to this resisitor. Power comes from Braker panel, to resisitor and then to blower motor. I have no power coming to resisitor, which tells me, a relay or fuse is blown. I cannot find that blown fuse or relay, or a broken wire. Tomorrow I will look for the Ambient pressure sensor and see if i can change it it helps. I doubt it..

 

I am sorry man, I couldn't help you, read all those pdf files in detail and check everything step by step. Good luck! Let us know once you fix it.

 

I understand. You were very helpful. Thanks for all the documents and wasting your time on me. I will update if I am able to fix.

 

AlaskanLS, Can you please re-attach the trouble shooting guide one more time please. I tried to download and it disapeared. I will print it this time.
Thanks

 

Here you go.

 

AlaskanLS,

Thank you for supplying the manaul information. That is exactly what I needed. I replaced Ambient sensor and heater relay. Not sure which one fixed it but its running now. I had changed heater relay before but no help. Manual also required to clear AC codes, by removing ECU-B fuse from engine Bay fuse box for 10 seconds. After which I started the AC and it came on. I win again.... Thanks everyone for your input.

 

I am glad your problem is fixed. 👍