What are the symptoms of Hissing from vents and slow loss of refrigerant in Ford Flex?

Different temperature on both sides of the cabin

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Hissing from vents and slow loss of refrigerant

Q: How to fix Hissing from vents and slow loss of refrigerant in Ford Flex?

The air conditioning stops cooling due to the complete loss of refrigerant. Leaks were located in the aluminum tubes running under the chassis to the rear evaporator, near the right rear wheel, or in the seals of the evaporator itself, where salt and road grime cause galvanic corrosion. Solution 1: Replace the corroded tubes with new original ones, but this is very expensive ($2000-3500) as it requires lowering the rear axle/suspension. Solution 2 (more cost-effective): Using the so-called block-off kit. Mechanics cut or disconnect the rear tubes at the front of the vehicle and install aluminum caps with double seals on them. This eliminates the rear air conditioning zone but restores full cooling for the front passengers.

in Ford Flex (2007-2019)

Symptoms

Different temperature on both sides of the cabin

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Technical diagnosis (Premium)

Recognized technical fault:

Auxiliary controller voltage instability detected

Technical analysis

Detailed analysis of HVAC controller operation parameters, CAN bus data readings, and diagnostic signal waveforms. Purchase PRO access or log in to read the full fault analysis.

Confirmed solution

Complete step-by-step repair procedure including module non-volatile memory reset, sensor calibration, and correct wiring routing. Unlock the full report to see the instruction.

Parts needed

Filters ferrite anti-interference / noise suppressor
Auxiliary starting battery (depending on cell status)

Workshop hacks

Important workshop tips for mechanics regarding bypasses without expensive control module replacement and manufacturer software service bulletins.

TSB / TPI service bulletins

TSB-24-HVAC-01TPI-2068943/2

A/C Technical Specifications

Refrigerant specifications for this model are available in the catalog.

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Hissing from vents and slow loss of refrigerant

Symptoms

A/C Technical Specifications

Other problems in Flex

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