FEH, A/C based battery cooling system to Cabin air based sys

"rear a/c works well and cooled down battery"

The first generation Escape Hybrid does not have a dual cabin (front-back) A/C system. I'm not sure what you mean by rear a/c system works well: are you referring to the outside air brought into the hybrid battery thru the split rear driver's side window (blend door opening)?-are you referring to the air conditioning brought into the hybrid battery via the coolant lines you can see on the underside of your vehicle especially near the rear driver's side wheel?- or?

Since your dash is displaying a warning message have you tried to read the "code" via code readers that can be found cheap at Walmart for around $25.00 or so? A scanguage can also read codes and one "X-code" can be inputted to display whether you have a blend door issue.

If I am correct :worry: , the 2010 Escape/Mariner now feature internal cabin cooling to the hybrid battery. There is software involved in this process and it is extremely unlikely you can covert your 2006 to this feature.

Your description indicates something is not letting the air flow rearward along the coolant lines into the hybrid battery. I don't have enough mechanical knowledge to pinpoint the exact issue but I can share information from my 2005 Helms manual.

This is from section 412-00B-20
When the high voltage battery approaches it upper temperature limite, the Traction Battery Control Module (TBCM) requests batttery cooling from the PCM. The PCM returns a sgnal to the TBCM allowing battery cooling under the proper conditons. The TBCM then monitor the the auxiliary evaporator for a temperature drop. The TBCM sends avoltage signal thru circuit 3703 to the auxiliary evaporator thermistor. The signal is returned thru circuit 3704 to the TCBM. A DTC (code) B2590 would indicate a rear air conditoning system fault. A DTC P0535 would indicate AC evaporator temperature sensor circuit failure. A DTC 2612 would indicate AC refrigerant distribution valve control circuit low. While DTC 2613 would indicate an issue with circuit high.

Somehow you got to get the codes read off of your vehicle.