Disco 2 Air con system pressure

Andy Warren · Sep 8, 2023

Hi all, my air con doesn't seem to be as effective lately. So as I've got a top up kit I thought I'd see if it needed topping up but the gauge indicated the pressure was high, near the red in fact, (according to the kit instructions) so I didn't take any action. I replaced the condenser dryer, eng cooling fan (both genuine) & the infamous pipe that rubs a hole in itself last year & had an air con specialist refill the system inc. oil.
I know the D2 system runs at a higher pressure than other vehicles which is why I did as @sierrafery said & disconnect the outside temp sensor to enable the eng. cooling fan to run whenever the air con is used. So after all that does anybody know if the pressure is to high ? (BTW mine has rear air con fitted) Many thanks in advance.

sierrafery · Sep 8, 2023

Hi, i dont understand much from that table you posted, what is the actual pressure on your's, the dual pressure swicth disables the compressor at 32 Bar.

Andy Warren said:
I did as @sierrafery said & disconnect the outside temp sensor to enable the eng. cooling fan

Do you still have the original type fan?... if you fitted some weak aftermarket which that one can't cool enough even if it runs constantly and the pressure will exceed the switch-off limit

Andy Warren · Sep 8, 2023

Hi, the instructions in the kit say the gauge should be in the purple zone between 33-38 psi but my system on the gauge reads 60psi in the yellow area so I wondered if that is normal for the D2.
The fan motor is the genuine LR one ( VDO) from rock autos in usa.
I forgot to say that the compressor cuts in when AC is called for.
Should I change the condenser rad as its the original one ? MY2001 & has done about 177,000 miles now.

Andy Warren · Sep 8, 2023

Pics of the fan motor.
Blimey fitted two years ago, doesn't time fly !

sierrafery · Sep 8, 2023

Andy Warren said:
Hi, the instructions in the kit say the gauge should be in the purple zone between 33-38 psi but my system on the gauge reads 60psi in the yellow area so I wondered if that is normal for the D2.
The fan motor is the genuine LR one ( VDO) from rock autos in usa.
I forgot to say that the compressor cuts in when AC is called for.
Should I change the condenser rad as its the original one ? MY2001 & has done about 177,000 miles now.

I dont know what pressures should be on the LP side but 60 psi there seems a bit high, my statement about the D2's higher pressures was about the HP side. It's possible that the condender is clogged so the LP is rising due to the restriction also as long as you are not monitoring the compressor's operation even if it kicks in when AC is switched on it can be disabled after a time by the DPS if the HP exceeds the limit.

what's the exact symptom? isn't it blowing cold enough from the beginning or it starts cold but it's "fading" on a long run? if you have nanocom watch it on engine -"inputs switch" section while driving with AC on to see when the clutch is on and off

Andy Warren · Sep 8, 2023

No Nanocom but my Foxwell NT530 gives this live data (truck has been in sun all day) on start up (cabin hot) with auto selected on ATC & fr. & RR air con on, the first pic shows what was happening. After about 3 miles the second pic shows what happened which I presume is when the ATC ecu was happy with the cabin temp.
It stayed off for about 10-12 seconds then the screen reverted back to the 1st pic for about 20 secs then the cycle continued for the rest of the 15 mile road test, so does that appear to about right ? The air coming out the vents was cool-ish but not as good as I remember then when I got back I was pleased to see 2 nice puddles of water underneath (see pic) which is not surprising as it's pretty humid here. So as that LP side seems a bit high & given it's age I will invest in a condenser rad (Nissens or any recommendations)? Many thanks.

sierrafery · Sep 8, 2023

Andy Warren said:
After about 3 miles the second pic shows what happened which I presume is when the ATC ecu was happy with the cabin temp.

Next time set it to "low" and watch the readings... if it behaves the same means that the pressure in the system is rising above the limit and the DPS disables the clutch not the interior temp sensor... though a new condenser would be a good move if your's is still the original, i also replaced mine when the vehicle was 20 years old cos it didnt cool well and it was a noticeable improvement after the swap... i went for Nissens which seems OK

i'll watch nanocom on mine next time i go for a longer ride and i'll tell you the result

Andy Warren · Sep 8, 2023

sierrafery said:
Next time set it to "low" and watch the readings... if it behaves the same means that the pressure in the system is rising above the limit and the DPS disables the clutch not the interior temp sensor... though a new condenser would be a good move if your's is still the original, i also replaced mine when the vehicle was 20 years old cos it didnt cool well and it was a noticeable improvement after the swap... i went for Nissens which seems OK

i'll watch nanocom on mine next time i go for a longer ride and i'll tell you the result

Thanks SF, I had it set at 16 degrees on auto but forgot to mention I did try the 'LO' (manual override) setting & it acted exactly the same. I'll get a rad on order just because of it's age if nothing else, many thanks again, all the best.

Andy Warren · Sep 9, 2023

Popped into the place that did my last air con fill & told them about the high pressure in the low circuit & they very kindly hooked it up to check it,see pic.
He said if the H P side had been reading low along with the L P side reading high he would suggest the compressor but as the HP side was OK he said it was the condenser rad, so when I get the new condenser I'll get them to empty the system & commence work.

Andy Warren · Sep 9, 2023

Has anyone used NRF or Maxgear condenser rads, if so was the fit/performance good ?
Many thanks.

Disco 2 Air con system pressure

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