No Cold Air

Mendez · Mar 26, 2014

Hi Guys...have had no cold air coming from the aircon since I bought the Disco 6 months ago. Since the summers coming, I got it regassed and fitted a new pump / compressor (mechanic told me it was shot), but still no cold air? ECON button is off...fan is blowing but compressor just won't click in. Fuses seem fine.
Only thing different about my Disco is the small electric fan in front of the rad is seized, but that shouldn't affect the Air Con....should it?
Next stop is auto electrician to see if he can trace a wiring problem.
Anyone come across this or got a fix?

sierrafery · Mar 26, 2014

that fan must spin when the aircon is on with some conditions:

Engine cooling fan control
While the A/C system is on, operation of the electric engine cooling fan, to assist refrigerant condenser operation, is
determined by a combination of vehicle speed and external air temperature. When cooling fan operation is required,
the ATC ECU outputs a cooling fan request to the ECM, which then energises the cooling fan relay. The cooling fan
request is output if vehicle speed is 80 km/h or less while the external air temperature is 28 °C (82 °F) or more. The
request is cancelled, and the cooling fan switched off, if either the vehicle speed increases to 100 km/h, or the external
air temperature decreases to 25 °C (77 °F).

the aircon must blow cold even without it but to work in parameters the fan must work too... that fan is important for the sake of the engine too so get it fixed ASAP

the fuse F6 and the relay R11(engine bay fusebox) both must be fine not just to seem fine

there is a dual pressure switch on top of the receiver drier (in front behind the grill), make sure it's well plugged, or bridge it's pins and then the compressor clutch must kick in

see attachment and run a diagnostic on it just to rule the sensors out

Mendez · Mar 26, 2014

Hi Sierra...that's for that.

Couple of things though...if I'm sitting in the driveway and turn the aircon on, and its under 28degress, than the compressor should run regardless of the fan...or not. Don't doubt you're probably right by the way....just trying to understand the relationship between the fan and the compressor for the aircon.

Also....mechanic is suggesting to install a bypass switch in the cabin which will just turn the compressor on/ off, so bypassing whatever the problem is. Would appreciate your view on that solution?
Cheers.

sierrafery · Mar 26, 2014

that's not a solution cos if you make it run forced by you without all the conditions to be met you might ruin it... the fact that you regassed it doesnt proove that you still have pressure in the system, and if you dont have pressure the dual pressure switch will not let the compressor to run...you better fix it for good as it should be...check system pressure first

there's no link between the compressor clutch request and the cooling fan request

read the description and operation in RAVE

Compressor control
To engage the compressor clutch, the ATC ECU outputs a compressor clutch request to the ECM, which then
energises the A/C compressor clutch relay. Compressor operation is governed by the evaporator outlet air
temperature, at one of two settings, dependent on the amount of cooling required. When more cooling is required, the
compressor clutch request is output if evaporator outlet air temperature increases to 4 °C (39 °F) and cancelled when
it decreases to 3 °C (37 °F). When less cooling is required, the compressor clutch request is output if evaporator outlet
air temperature increases to 11 °C (52 °F) and cancelled when it decreases to 10 °C (50 °F).

No Cold Air

Mendez

Active Member

sierrafery

Well-Known Member

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Mendez

Active Member

sierrafery

Well-Known Member

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