Thread: D4 A/C Compressor issue

Whatever

Originally Posted by haydent

i doubt there is anything wrong, but i will get the opinion of my ac tech.

im not worried as everything is monitored by the car:

No it isn't.

Originally Posted by haydent

if the fan rpm wasnt within the requested rate an error would be logged

No it won't.

Originally Posted by haydent

if the pressure was too high it would cut the pump valve and if it was still too high it would raise an error

Yes it will; No it won't.

None of the conditions you've mentioned will log a code.

Originally Posted by haydent

i doubt there is anything wrong, but i will get the opinion of my ac tech.

im not worried as everything is monitored by the car:

if the fan rpm wasnt within the requested rate an error would be logged
if the pressure was too high it would cut the pump valve and if it was still too high it would raise an error

An earlier post you did state the AC Tech said the pressure started a bit high,then the fan cut in,which is exactly what one of your graphs shows.
That should ring alarm bells.

Cycling at pressures over 3,000Kpa,on a safety device,will not take long to wreck something,and is far from normal.
That is well over double normal operating pressures.

Do whatever you want to do,we can only offer advice.It is your vehicle.

You asked for advice and it was given, you then presented an anomaly and was advised that something was not as it should be. If I were you I would seek a second opinion from a professional. These systems are quite smart, but if there is a faulty component somewhere it can't diagnose itself, it can only shut down and will restart when the result of the problem ie. excessively high pressure drops because the compressor has stopped pumping.
You really need to know what is causing the pressure to spike.
Fixing something yourself if you have the capability is fine, but trying to fix something that you don't understand is fraught with danger.
This is bound to end up costing more than if you had gone to someone who knows these systems in the first place.

Just had my '01 d2 weighed, 450g left of 700g target. Cost about as much for "topup" as full refill though works better now though


Tech said the pressure being high on rrs when the fan is not running is OK.

just noticed more past replies since "whatever" post, so will reply to them now, this thread is becoming more work than the car work itself

Originally Posted by BradC

No it isn't.

No it won't.

Yes it will; No it won't.

None of the conditions you've mentioned will log a code.

The Engine Control Module (ECM), which determines the required fan speed, controls the level of clutch engagement. The ECM determines
engagement based on the coolant, charge air, ambient and transmission oil temperatures and the A/C pressure.

DTC B1B7885
System Pressure Pressure signal above allowable range

• Condenser fault
• Cooling fan fault

DTC B1B7884

• System Pressure Pressure signal below allowable range
• Refrigerant leak

DTC P049300
Fan Overspeed (clutch locked)

• Seized viscous coupling
• Fan speed sensor failure

DTC P049400 / P049411
Fan Speed Low

• Viscous fan restriction
• Viscous fan solenoid circuit high resistance
• Viscous fan solenoid circuit short circuit to ground
• Viscous fan solenoid failure

DTC P049512
Fan Speed High

• Viscous fan solenoid circuit short circuit to power
• Viscous fan solenoid failure

There are also more error codes if the fan speed sensor or control signal go out of range or performance characteristics.

You really need to know what is causing the pressure to spike.

its just the fan running or not, you can see that from the graphs

An earlier post you did state the AC Tech said the pressure started a bit high,then the fan cut in,which is exactly what one of your graphs shows.
That should ring alarm bells.

yes thats what i was showing with the graphs, and he just thought the thermofan wasnt working and started looking for one, but couldnt find it, then we heard what sounded like a thermo fan start and run, and the pressure dropped to normal, later i realised its just the viscous engaging or not rather than a thermo fan.

Cycling at pressures over 3,000Kpa

It must be able to handle it, as thats about the limit its programmed it to cut the compressor in and out at, and it didnt generate an error code so seems legit.

Bear in mind its not often you just start the car and idle it with the AC set to max, normally you start driving which will increase air flow due to movement and higher rpm.

Hmmm. Doing the same with my AC, never gets to cutout in the same scenario. Idling in the Garage on Lo. Peaks at about half of your figure

Originally Posted by DiscoJeffster

Hmmm. Doing the same with my AC, never gets to cutout in the same scenario. Idling in the Garage on Lo. Peaks at about half of your figure

mine doesnt always do that, there is a chart above where it acts without the peak, i think it has something to do with the initial viscous state.