Volkswagen Polo Service & Repair Manual: Pressures, Checking

Volkswagen Polo Service & Repair Manual / Refrrigerant R134a Servicing / Pressures, Checking / Refrigerant Circuit Pressures (with A/C Service Station), Checking / Pressures, Checking

Note

Check cooling performance. The A/C system is functioning correctly when the air flowing from the instrument panel vents has a temperature of 7⁰C or lower.

Setting on Climatronic “LO”.

Setting on A/C system “AC” on; “max”; “cold”.

Connections with valve and service connections for measuring and checking.

–	Turn off the ignition.

–	Connecting service station. Refer to → Chapter „Connecting Service Station“.

–	Take pressure gauge readings (two possible results).

Ambient Temperature in °C (°F)	Pressure in Refrigerant Circuit in bar (psi) Positive Pressure
15 (59)	3.9 (56.57)
20 (68)	4.7 (68.17)
25 (77)	5.6 (81.22)
30 (86)	6.7 (97.18)
35 (95)	7.8 (113.13)
40 (104)	9.1 (131.98)
45 (113)	10.5 (152.28)

Note

Temperature of refrigerant circuit components should be equal to ambient temperature.

Pressure will deviate from values in table if individual components of refrigerant circuit are warmer or colder.

At absolute pressure, 0 bar/psi corresponds to absolute vacuum. Normal ambient pressure (positive pressure) corresponds to 1 bar (14.5 psi) absolute pressure. 0 bar/psi pressure corresponds to an absolute pressure of 1 bar (14.5 psi) on most pressure gauges (indicated by 1 bar (14.5 psi) below 0).

On vehicles with High Pressure Sensor -G65- with which the measured pressure is displayed in the measured value block, the measured pressure should correspond to the values in the table.

Refer to → Rep. Gr.87.

The refrigerant circuit pressure is lower than indicated in table

Not enough refrigerant in refrigerant circuit

–	Determine refrigerant circuit leaks. Refer to → Chapter „Refrigerant Circuit, Tracing Leaks, with Electronic Leak Detector -VAG1796-“.

–	Check the pressure relief valve.

If pressure relief valve has responded:

–	Check the coolant fan activation.

–	Check refrigerant lines and hoses for cross-section constrictions caused by inadequate bending radii.

–	Check refrigerant pipes and hoses for external damage.

–	If no malfunction is found, flush refrigerant circuit with compressed air and nitrogen.

The refrigerant circuit pressure is in line with table or is higher

–	Start the engine.

–	For vehicles with an electrically-driven A/C compressor, switch on the ignition.

WARNING

Hybrid vehicles have a high voltage system. Danger of electrical shock! Inspect the high voltage components visually before beginning. Follow the General Warnings. Refer to → Hybrid Electric Equipment; Rep. Gr.93.

–	Set the A/C system to maximum cooling output.

Note

If the low pressure switch was removed to connect the service station, bridge the electrical connections in the corresponding connector for the pressure measurement.

A/C compressor is driven by the engine via A/C Clutch -N25-.

The A/C Compressor Regulator Valve -N280- is activated by the Climatronic Control Module -J255-.

Refer to → Rep. Gr.87.

If A/C compressor is not driven with the engine running or regulating valve is not actuated:

–	Determine and eliminate cause e.g. by checking air conditioner DTC memory.

–	Observe test conditions.

–	Check the A/C Clutch -N25- voltage supply. If it is OK, repair the A/C clutch.

–	Check activation of A/C Compressor Regulator Valve -N280-.

Refer to → Rep. Gr.87.

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