Original Fault Symptoms.
Renault Clio (2002 on) with full Automatic Air Conditioning
- Everything working fine until I stopped engine for about half hour on return found no demist or air con working. All front panel lights/systems operational and illuminated on the air con panel e.g. Temp, fan intensity - just no actual fan/demist/air movement. Checked all fuses marked with a fan symbol in passenger side fuse box - all ok and so are all under bonnet fuses. Guess it’s a fuse/relay/supply problem to the fan but can't find fault. Any advice appreciated please. Thank you, from Ian
Later Comments:
It turned out to be the Air Conditioning Fan Power Unit (61) given these problems it’s likely to be either this unit or the climate control computer. Some models have the resistor pack - this is in the fan housing but the power control module (Air Conditioning Fan Power Unit) is located in the air flow pipe work between fan and cabin, after the filter. It’s worth checking it’s faulty before buying as it costs £94 quid!.
Testing System
NOTE: Unit reference numbers in brackets refer to items marked in Circuit diagram for Automatic Air conditioning in Haynes Renault Clio manual 4168 - Page 12.27
Initially, check 60A Fuse F8 and 30A Fuse F11 in Engine Bay Fuse box (4) for continuity.
Open bonnet then, remove drivers side scuttle cover (remove wiper arms with blades if necessary to gain access to Air Conditioning Fan Unit (62) and Air Conditioning Fan Power Unit (61).Ignition ON
Check for 12v on pin 4 of the Air Conditioning Fan Power Unit (61) and also on pin 1 of the Air Conditioning Fan Unit (62) Note: Both wires are Red
If 12V is present at both points, then temporarily link the earth at pin 5 (black wire) of Air Conditioning Fan Power Unit (61) to pin 2 of Air Conditioning Fan (62) then check that the fan operates at full speed. If not, then either the Air Conditioning Fan motor (62) is faulty or black earth lead at pin5 is not grounded to chassis.
If 12V is not present at points detailed in previous paragraph, then set Ignition to OFF.
With ignition OFF, locate the Cold Air Delivery Relay (63) which is a yellow relay on an individual holder in the Engine Bay Fuse Box (4).. Check for 12V on terminal 30, an earth (chassis) connection on terminal 85 and 0 Volts on terminal 86 of the relay
Set Ignition to ON and then check 12V is now present on terminal 86.
If 0 Volts is still present at terminal 86 of the relay (yellow wire), then switched supply from Ignition Switch (2) is missing. Check 12Vsupply at both sides of Fuse F34 (20A) in Main Fuse Box(3) then, if satisfactory, check for open circuit of all yellow wiring between relay terminal 86 and Main Fuse Box(3) If no 12V supply to Fuse 34, check wiring to and from Ignition Switch (2 ) including 60A Fuse 8 in Engine Bay Fuse Box (4)
With supply of 12V at terminal 86 of relay, 12V should now switched from terminal 30 to terminal 87 of relay. Replace relay if this does not occur.
With Ignition still set to ON, check 12V is now present on both terminal 4 of the Air Conditioning Fan Power Unit (61) and terminal 1 of the Air Conditioning Fan Unit (62).
Check for earth on pin 5 of Air Conditioning Fan Power Unit (61) Note:- the pins are numbered 1-5.
Disconnect the connector from the fan power unit and then, with ignition ON, temporarily link together pins 1 and 5 of the free connector socket..With the link in place, the fan should run at full speed - if not the fan is faulty.
To check for correct operation of the Air Conditioning Fan Power Unit (61), which controls the speed of the fan in response to signals from the Air Conditioning Unit(56) and the fan speed controller, perform the following sequence:-
With the Air Conditioning Fan Power Unit (61) reconnected;-
Check the voltage between earth (chassis) and pin 2 of the unit (this is difficult to access due to the compact nature of the wiring). It should vary as follows
speed 0 13.94v
speed 1 11.36v
speed 2 10.17v
speed 3 8.93v
speed 4 7.69v
speed 5 6.34v
speed 6 5.13v
speed 7 3.8v
speed 8 0. 1.4v
If it does vary as detailed (approx voltages), then the Air Conditioning Unit(56) is operating correctly. If the fan speed does not vary in sequence, or the fan speed remains constant, then replace the Air Conditioning Fan Power Unit (61)
Repairing the Air Conditioning Fan Power Unit
The following instructions are offered to those with basic experience of electronic circuit repairs:-
Open bonnet then, remove drivers side scuttle cover (remove wiper arms with blades if necessary. Unplug large plug with black wire to fan then remove securing screws. The device sits in the air passage with a large aluminium heat sink on it which is cooled by the air passing over it. At first glance, it looks like a 5/6 way connector bolted to the air passage but it's actually inserted into the airway. Dismantle the casing then peel away silicone sealer from the soldered side of circuit board around the power MOSFET device. De-solder and then remove the MOSFET.
Caution: The power MOSFET device is very sensitive to damage caused by static discharge. Ensure all items. including hands, are grounded before they come into contact with the device leads.
The original power MOSFET fitted is normally a 75344G3, 75A, 55V device, but this item is no longer manufactured and is therefore difficult to obtain. The best, easily obtainable, equivalent is currently available from Maplin, and is a Fairchild type HUF75337P3 at a cost of £1.95. This has an identical power specification but a slightly higher Drain/Source resistance (0.014 Ohm compared to original item’s 0.008 Ohm). The P3 suffix, however, indicates that it is in a TO-220 package in place of TO-247 necessitating that the clamp is ‘closed’ slightly, before fitting the new item to give it a secure fit. Pin connections are the same so, when fitted securely in place, solder into position. Replace any silicone sealer removed during disassembly.
Note: If a HUF75337G3 or a HUF75344G3 can be obtained, then the suffix G3 indicates a TO-247 package which is the same package as found on the original device. However, Maplin do not currently stock this latter item. Another alternative but identical device, which is currently manufactured by Toshiba is a 2SK22987 which is in a TO-247 package. This item is distributed by Harris. A more modern near equivalent, with very low Drain/Source resistance of 0.005 Ohm, but in a TO-220 package, is an STB80NF55-06.
Kayball, December 2009