hello all.
I have a 1999 GS300 that’s having strange heat issues. I have no heat on drive side (ac works great on both sides and directions). I get some heat on passenger side when outside temp is 50 degrees or above. I’ve read all the post I could find about heat and servo motors. I’ve tried all possible fixes and no luck. I’m hoping you guys could offer other things to try.

These are the fixes I’ve tried.
1. Flushed cooling system and replaced antifreeze
2. Remove hoses from heater core and spray water in one line and verify it flowed from other line
3. Verify both heater core line inside car were hot
4. Replaced radiator cap and thermostat
5. Ran climate control diags and received codes 21, 24, and 46 (21 and 24 are solar sensors) 46 driver servo malfunction.
6. Clean and swap driver side servo with no luck
7. Removed glove box and verify the other 3 servos were working
8. Swap climate control unit
9. Manually moved arms on air box (behind radio) to verify they were not broken.

It's getting cold in North Carolina

 

I'd say go ahead and replace with new unit, the driver's side servo. If cleaning and swapping didn't fix it, I'm sure new would.

Also, did you check to make sure the arm was in the track of the driver side servo? If you're still getting 46, then something is still wrong with the servo.

 

the arms are on track. don't mind buying a new driverside servo but didn't want to spend the money unless I could figure out the strange heat issue on passanger side below or above 50 degrees

 

im having the exact same problem, although im pretty sure i have no diagnostic with the jzs147 2j swap. I cant even program another master key