air con still does'nt work

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hunterandthehunted said:
could be,
although what you said about the ecu he said about and asked whether i had it plugged
in for fault codes etc.

now forgive me for being thick but i thought the hevac computer was for this, hence the
book display which incidentally has gone out on mine since all the work...

irishrover says that fans never come on in uk cause of temp in uk, have you been outside today?
Click to expand...

Hevac provides the enabling signal, control is from the pressure switches. The fans rarely come on on mine. On petrol the engine ECU can also call the fans.
 
hunterandthehunted said:
pressure switches next port of call then,
where are the 2 switches?
Click to expand...

Forget the fans, your air con will function without them, at least until the aircon pressure calls for them.

The air con dual pressure switch also operates the compressor clutch according to RAVE but requires the enabling signal from Hevac.
Assuming you still have pressure in the system, you could have a fault with the Hevac head unit, they are apparantly known to give trouble. Try turning the air con off and on with the switch at the top right of Hevac, the light on the switch should be off for the aircon to operate.

Otherwise it gets into electrical trouble shooting with a test meter:eek::eek::eek:
 
Reading through RAVE, I see that pressure switch 1 will disable the compressor if the pressure in the air con is too high or too low. I'm still inclined to think that my first port of call would be a pressure check. However you could check that pressure switch 1 is closed.

What year is your car? I'm quoting from the 99 on drawings
 
datatek said:
reading through rave, i see that pressure switch 1 will disable the compressor if the pressure in the air con is too high or too low. I'm still inclined to think that my first port of call would be a pressure check. However you could check that pressure switch 1 is closed.

What year is your car? I'm quoting from the 99 on drawings
Click to expand...


95
 
The differences with the earlier diagrams are in the connector numbering etc. Functionally there is not a great deal of difference so for the moment there are many things that could be checked before the differences matter:D
 
Just noticed that your car will have a thermal cut out located on the compressor which I have not seen in the electrical drawings but it appears to cut out the compressor clutch. Worth a look.

The pressure switches 1 & 2 are located on the receiver dryer on the front nearside of the car just behind the headlight I think.
 
yep thats where it is.
in regards to the thermal cut out switch, whats that all about

i am told that the clutch gap is to big and am going to have it adjusted, but
no one knows the correct gap.

any ideas?

i think from what you describe could be it, because sometimes it works although
its not brilliant and then it justs stops until randomly starts again
 
hunterandthehunted said:
yep thats where it is.
in regards to the thermal cut out switch, whats that all about

i am told that the clutch gap is to big and am going to have it adjusted, but
no one knows the correct gap.

any ideas?

i think from what you describe could be it, because sometimes it works although
its not brilliant and then it justs stops until randomly starts again
Click to expand...

Sounds more like electrics then, thermal cut out, relays, pressure switches, or head unit. Can't be more specific without being able to stick a tester on it.:(
 
I take it all Land Rover air con systems work in the same manner, here's what RAVE says about the TD5 disco regarding the fan.

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).

hope this helps, couldn't find anything similar for the Range Rover
 
Last edited:
Datatek said:
Sounds more like electrics then, thermal cut out, relays, pressure switches, or head unit. Can't be more specific without being able to stick a tester on it.:(
Click to expand...

well the relays have been tested and all ok.
having a borrowed pressure switch put on next wednesday to test.
if it was the head unit wouldnt the cheque book be on
 
biggeeeee said:
I take it all Land Rover air con systems work in the same manner, here's what RAVE says about the TD5 disco regarding the fan.

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).

hope this helps, couldn't find anything similar for the Range Rover
Click to expand...

That does not sound anything like the description in RAVE for the P38, for a start the engine cooling fan is engine driven not electric
 
Again for the disco, the fan seizing is a common problem as they are seldom used.
I had to replace the fan as it was seized solid. I managed to get one from an older model Range rover and modified it to suit the disco rather than shelling out loads of dosh for something that probably wouldn't get used all that often.
 
gavbriggs said:
i need to check this as temp on mine rises, has done the last couple of days since using aircon, dont think fans are kicking in!!!
Click to expand...

My diesel runs hotter too since I did the aircon, but if you feel the temperature of the condensor it's not surprising:eek: the only surprise is that the engine stays cool at all as the engine rad is after the condensor and the intercooler:doh:

As for the fans, the are operated by air con system pressure only on the diesel whereas on your V8 the engine ECU is supposed to switch them if the temperature is too high.:eek:
 
i'd like a switch, i'm fond of switches, to operate em when required!!! i'm getting a test book session on thurs so i will get him to test em if he can!
 
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