blocked heater core? failed interior cabin sensor.
HIM not programmed for Dual Zone (so the right side of the car still blows cold air?

You need to set the protocol to 11 bit CAN, 512k. atsp6 I think is what you want. The 'a' you mentioned above leaves the ELM in auto mode and should do the same thing, but if it doesn't find 11 bit can 512, it will start looking for the PCM on other protocols. SO in this case either would work.

The HIM responds to messages with a CAN header of 733.

Then you need to use a mode 3B command to program the HIM, which according to J2190 is 'write by data block'.

In this case the HIM mode is block 00. And the values are:

0F - Heater only mode
55 - Manual Climate Control
AA - Auto Climate Control.

So setting a HIM to Manual would be:

ATSP6
ATSH733
3B 00 55

To see that this value is written correct, you do a mode 21 read of block 00. Which is simply

21 00

When you issue a command to header 733, expect to get a response message with a header of 738. SO the purpose of doing the ath1 command is to turn headers on so in the response you can see the 738 bit.

Finally, if the mode 21 lookup shows the value written correctly, you may need to completely power off to have the value take effect. This may even include disconnecting the battery.....


Lukeyson