Thread: D4 A/C Compressor issue

Originally Posted by haydent

there would be another limit above that which would be the safety limit that triggers an error code

Are you sure about that?

its not purely a safety device, its general purpose to work with the variable output control valve, like a thermostat

This is entirely incorrect. A hp cutout switch is not part of the normal operation of the system. Whoever told you that has no idea how an a/c system or a variable output compressor operates.

Originally Posted by scarry

Are you sure about that?

well the fact i have not had that error come up ,and that error exists would suggest i have not hit that limit

Originally Posted by LuckyLes

its not purely a safety device, its general purpose to work with the variable output control valve, like a thermostat

This is entirely incorrect. A hp cutout switch is not part of the normal operation of the system. Whoever told you that has no idea how an a/c system or a variable output compressor operates.

its not a hp cutout switch, its a pressure sensor that feeds its data to the ecu that uses it amongst other data to make decisions about controlling the pump, viscous fan and other things.

So haydent - have you actually ever seen it oscillating between the two high pressure set points again? Or was that shortly after you had put the system all back together?

Could have just been a case of the system recalibrating the required duty cycle for the pulse width modulator which controls the flow through the system.

And the compressor does have a seperate pressure relief valve (as a safety device). That is the one you hope never needs to do anything.

And not saying your system is or isn’t working as intended - but curious to know - is there actually still a problem with the a/c at present?

no problems. the time i graphed it doing this was not the first time it ran with the new pump, just once id gotten home from getting refilled, this was the first time i graphed it, at this stage not graphing fan speed, but you can see some pump signal changing at the peak. have not seen it do this again, but have not graphed that much

Screenshot_20221231-103201_IIDControl.jpg


ive also graphed it just getting high when the fan was not spinning enough

Screenshot_20230107-081431_IIDControl.jpg

and this pretty normal behaviour
Screenshot_20230101-190927_IIDControl.jpg

My D3 was/is spiking in a similar fashion at idle. A/C tech who last regassed it mentioned that the pressures where too high and that the fan was not doing its job. It does kick in and reduce the pressures so I hadn't gotten to concerned over it. Does make me wonder what is a normal operating pressure for these vehicles to spike to at idle?

I've just had the rear A/C evaporator fail so could be related to the pressure or judging by what the evap condition looks like I suspect it may be corrosion
IMG_20230109_152838_847.jpg

A bit of a coincidence, but I have been travelling for the last 6 weeks, from Qld down to western Vic and now on my way home. The day before yesterday I felt that the a/c wasn't quite performing as it normally does. I normally set the temp to 22 and leave it there, hot weather cold weather or heat wave. So yesterday we left Yea and it was in the mid 30's outside, a/c cool but not what it should be, so I rang a number of places before I finally got onto a young guy in Wangaratta, who was prepared to check it out. He connected his gauges and ran it up, sure enough very high discharge pressure, high suction pressure, which I knew because I had felt the exposed suction tube, and viscous fan speed up and down. Degassed the system, evacuated and then regassed with the correct charge, and ran the system at about 1800 rpm to check the operation. Everything as it should be. 37deg celcius ambient, head pressure 250psi, suction pressure, about 25 to 30psi, doors open, so high load on the system, viscous fan operating normally, icy cold air from the vents, front and rear.
The op's a/c has a problem of some kind, and if not identified and fixed you will lose another compressor.
Good luck
LuckyLes
PS, this is the first time my a/c has been touched since the vehicle was new, 165000klm,s first registered Jan 14, built Nov13.

Originally Posted by LuckyLes

A bit of a coincidence, but I have been travelling for the last 6 weeks, from Qld down to western Vic and now on my way home. The day before yesterday I felt that the a/c wasn't quite performing as it normally does. I normally set the temp to 22 and leave it there, hot weather cold weather or heat wave. So yesterday we left Yea and it was in the mid 30's outside, a/c cool but not what it should be, so I rang a number of places before I finally got onto a young guy in Wangaratta, who was prepared to check it out. He connected his gauges and ran it up, sure enough very high discharge pressure, high suction pressure, which I knew because I had felt the exposed suction tube, and viscous fan speed up and down. Degassed the system, evacuated and then regassed with the correct charge, and ran the system at about 1800 rpm to check the operation. Everything as it should be. 37deg celcius ambient, head pressure 250psi, suction pressure, about 25 to 30psi, doors open, so high load on the system, viscous fan operating normally, icy cold air from the vents, front and rear.
The op's a/c has a problem of some kind, and if not identified and fixed you will lose another compressor.
Good luck
LuckyLes
PS, this is the first time my a/c has been touched since the vehicle was new, 165000klm,s first registered Jan 14, built Nov13.

So what was causing the issue?