What are the symptoms of Hissing from vents and slow loss of refrigerant in Audi A1?

No cold air from vents. Different temperature on both sides of the cabin. Unusual noises when A/C is turned on

High Priority 95% confidence

Hissing from vents and slow loss of refrigerant

Q: How to fix Hissing from vents and slow loss of refrigerant in Audi A1?

Leakage of the evaporator integrated inside the HVAC module (covered by TSB Bulletin 87 25 98 2064077/6). The diagnosis is confirmed electronically by pumping forming gas. Proper repair and replacement of this evaporator variant requires special care: the relay and fuse housing No. 3 (Relay and Fuse Carrier 3 -SR3-) must be disconnected and clipped into place with perfect accuracy. The manufacturer points out that an error in putting it down and screwing it in causes water to penetrate into the vehicle's cabin.

in Audi A1

Symptoms

No cold air from vents
Different temperature on both sides of the cabin
Unusual noises when A/C is turned on

Verifying license...

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

(8X) kompresor Denso (5Q0 XXX XXX)

Refrigerant: R134a Amount (g): 500g Oil: PAG PAO 68 lub PAG ISO 46 Oil (ml): 110ml

(8X) kompresor Sanden/Delphi (5NO XXX XXX)

Refrigerant: R134a Amount (g): 500g Oil: PAG PAG 46 lub PAO 68 Oil (ml): 110ml

kompresor Denso (1KO XXX XXX)

Refrigerant: R134a Amount (g): 500g Oil: PAG PAG 46 lub PAO 68 Oil (ml): 90ml

See full specification

Have this problem?

Generate a personalized AI report for your Audi A1 or book a workshop visit.

Generate AI report Schedule visit

Hissing from vents and slow loss of refrigerant

Symptoms

A/C Technical Specifications

Other problems in A1

Have this problem?