cdew002

Hey All,

I just noticed that my rear heat doesnt work. The A/C DOES work, however. Any ideas? Mann? Know where to start troubleshooting?

Thanks,
Cliff

mann777

To start with your Troubleshooting, open the Driver Side Engine Bay Fuse Box and Remove the IG1 fuse from the driver side Junction Box & check if the connectivity of the fuse exists if not replace with same ampere, Next if the Fuse is Ok,t inspect the Heater Relay No 1 and check for continuity, This is how you should test the Relay on the following terminals which are numbered (1-2 ) . Check the condition with a Digital tester connecter using the following relay points & should give an output of 62.5-90.9 Ω . You should apply battery voltage between terminal 1 & 2. Connect on terminals 3 & 5 there should no continuity . And Connect on Terminals 3 & 4 it should have continuity.
If there is any different iin the output of the above condition, Replace the Relay.

To check the Relay position in the Junction Box, Once the Box Cover is removed. the inner side gives you pictorial representation of the Fuse and relays.
Notes - Edited

Johnny Rad

I think the rear vents in the ceiling are a/c only.

redrocks

Yes, A/C from the ceiling. Heat ducts are under front seats.

cdew002

Checked fuse - it is still good.

To clarify, the front heat works. The rear A/C blows ice cold when I switch the rear selector to the red side just like it blows on the blue side.

cdew002

Roger that on the relay. I'll have to check that later.

On a side note - are the Japanese able to see in the dark? I only ask because they decided not to put a light in the engine bay. As an American without night vision, I wish they had put an overhead light in there.

mann777

Could you check one more fuse that is RR Fuse from the junction box.

gsobol

As stated prior. The selector in the second row controls secondary A/C only. You can't get heat from these vents. Heat is controlled from the front selector only and it comes from the vents under the front seats. The selector in the rear is misleading, with the blue and red areas (it only indicates not-so-cold in the red, and freezing in the blue).

cobra2top

Exactly! I too started to fiddle with the rear "heat" from the rear controls the first cold day only to have my kids swear it was cold air coming from the ceiling vents. After more research I found the rear heat is only from the floor. Never really sure why Lexus did not just let the heat work from the ceiling. I would think if you can route AC through the vents, that heat would be something as simple of adding a vent hose and completing the connection.

Oddly enough I traded in a 03 Explorer for the GX and that had both heat and AC that came out of the ceiling. I could warm that truck up in minutes. I just assumed it was the same when I was at the dealer. I think one of only a few misses on the GX......

cdew002

Oh. Well then that is a very misleading control! All is right, then.