Of course, Rick. Until then, you're flying blind. Not you personally you understand, a generalisation, although you probably have your moments. ;) :DQuote:
that was my thought too Des, but would want to see the gauge readings first.
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Of course, Rick. Until then, you're flying blind. Not you personally you understand, a generalisation, although you probably have your moments. ;) :DQuote:
that was my thought too Des, but would want to see the gauge readings first.
:lol2:
If you ask me, Rick tou are pretty much spot on
In my guess its tripping on low or high pressure (dual switch, normally on the liquid line near the reciever drier)
Several things will cause low pressure cut out, main thing is lack of refrigerant, but a blockage - but this will be obvious during tickover as well)
High pressure tripping is nomally caused by
Too much gas, dirty condenser coil, oil contamination, or a blockage on the suction side.
Run it and do a 'feel test' first,
The discharge feom the compressor should be hot, the liquid line from the condenser should be warm towards hottish depending on ambient, and the suction line back to the compressor should be cold.
Typical pressures are (on R134a) 40 - 50 psi suction, and 180 - 250 on discharge.
Then run another test start the car, switch the air con on, and whilst you watch the clutch, have someone rev the engine to 2000 - 2500 rpm - and if it cuts out suspect its pressure.
If you want any more info - pm me, and I;ll put something together for you.
Ladas
I had a bit of a look today and this is what it resulted in.
I started the Disco and the Aicon did not work
I checked the compressor clutch, it works ok when power feed to it directly.
I removed the compressor clutch relay and bridged the power supply to the compressor feed wire and it ran and got cold air immediately.
Of course it did not cycle as it was constantly on.
I unscrewed the hi/low cutout switch cap and pressed the valve for a split second and it discharged a lot of oil in that short burst. Is it normal for oil to be present in that particular spot?
The suction line was cold and the supply line was hot on the compressor
I checked and replaced the compressor Clutch relay and the A/C logic relays and the system worked.
I drove it for about 20 kms and it was nice and cold and cycled ok.
I parked it in a shopping centre and returned 1/2 later and it was blowing hot air and the compressor wouldn't run.
I drove it for another 20 kms, switched off at another stop and returned 15 mins later, drove home and after a few kms it came on cold as ever.
I am starting to suspect a blockage at the hi/lo pressure cut out switch since there was a lot of oil.
Was thinking of cutting the 2 wires from the switch and connecting them directly by passing that switch to see if the switch is tripping out the system
I had this in my Disco, I bypassed the pressure switch and the problem went away, after a long run it realeased presure from the valve ?!?!? not sure if that was good for it or not, but I hooked it back to the pressure switch and it has never happened again !
So its my guess that it was the high pressure from maybe a over-gas that caused it ?
Cheers
PM Ladas, he knows everything about this stuff, he helped me with a tractor which the manufacturer and a couple of aircon (so called ) specialists couldnt fix.
What I would suggest as well. When it occurs again, electrically bridge out the HP control & see what happens.
It's not beyond the realms of possibility that the HP control is buggered.
no. Blockages are usually contained either to the dryer or the TX/metering device. Oil is constantly circulating in the system.Quote:
Originally Posted by Rovernaut
As Des suggested earlier, moisture can cause inconsistencies like this (TX valve orifice freezes up, doesn't unblock till valve comes above zero*C). A partial freeze up will drop the suction pressure and cut the compressor on the LP control. After the moisture has been released from the TX valve it will tend to circulate and if the dryer is already saturated with moisture, it either won't capture it or release some more, presenting the same problem. BTW, a dryers moisture holding capacity diminishes with rising temps
As Des and Ladas said, pressure switches can also be faulty, could be a crook connection, etc.
Faulty TX valve power elements or a partial blockage of TX valve strainer will be more consistent in nature.
Dryer blockage will also be a more consistent fault, although it's easy enough to check when running by feeling for a temperature difference between inlet and outlet of dryer. Lines in and out should be the same temp, if the outlet is colder, dryer is partially blocked.
Try what Des suggested re HP/LP.
BTW, is the condenser fan coming on ?
yep the condesor fans come on as soon as the dash aircon switch is switched on.Quote:
Originally Posted by rick130
Thinking out loud here.;)
But does it/they stay on all the time the A/C is on, as it could fail without you knowing & cause an HP trip. Cools down & awaaaaaaay you go again until the next time it overheats & causes another trip.
If there are two of them, just one failing, could cause a trip.
Do these condenser fan motors have hi - temperature cutouts embedded in the windings, does anyone know?
As it seems to happen after you have parked up, it may be heat soak causing it & not when you are driving, as the moving air flow may hold it at bay.
As I said, thinking out loud.:D