Un heaven tick over when AC on, LWF and aftermarket ECU
05-16-2018, 08:05 PM
#1
Three Wheelin'
Thread Starter
Un heaven tick over when AC on, LWF and aftermarket ECU
Hi guys,
wonder if anyone experience the same issue, since I remapped with an aftermarket ECU, a few years ago, when I switch on my AC, the tick over is un heaven, the compressor kicks on and off every few seconds.
The engine has the LWF, I don’t experience staling issues at all when driving , I know the CCU is connected to the ECU,
just wonder if it’s unavotable due to the LWF, or the mapping needs correction and improvement or anything wrong with the CCU or compressor ?.
Shame I could not upload a video.
thanks
konstantin
wonder if anyone experience the same issue, since I remapped with an aftermarket ECU, a few years ago, when I switch on my AC, the tick over is un heaven, the compressor kicks on and off every few seconds.
The engine has the LWF, I don’t experience staling issues at all when driving , I know the CCU is connected to the ECU,
just wonder if it’s unavotable due to the LWF, or the mapping needs correction and improvement or anything wrong with the CCU or compressor ?.
Shame I could not upload a video.
thanks
konstantin
05-16-2018, 10:42 PM
#4
Rennlist Member
I finally fixed my air con, have a SW chip and have a LWF. When the car is cold and I pull up to an intersection with the AC on, then it sometimes stalls.
I think you have two problems. One the freon is low causing the AC compressor clutch to cycle on and off and two, the ECU needs tweaking for the extra load when the AC switches on
I think you have two problems. One the freon is low causing the AC compressor clutch to cycle on and off and two, the ECU needs tweaking for the extra load when the AC switches on
05-17-2018, 02:42 AM
#5
Three Wheelin'
Thread Starter
Thank you guys,
I did not though the freon could be low as the air is fairly cold, I will book for a refill , I hope it will improve ,
If not, I guess I may then need to ask a little fuel/ ignition adjustment to my tuner, he can access to my ECU from my lap top using TeamViewer , very helpfull.
I did not though the freon could be low as the air is fairly cold, I will book for a refill , I hope it will improve ,
If not, I guess I may then need to ask a little fuel/ ignition adjustment to my tuner, he can access to my ECU from my lap top using TeamViewer , very helpfull.
05-17-2018, 06:29 PM
#6
I would imagine an aftermarket ECU with an AC port of sorts would either allow you to up the rpms when the compressor clutch engages or disengage the compressor clutch in WOT.
Yes, cycling on and off could be low refrigerant or it could be the ac pressure switch. Toss on a set of gauges and write down your ac low and high pressures at idle when the clutch engages.
Yes, cycling on and off could be low refrigerant or it could be the ac pressure switch. Toss on a set of gauges and write down your ac low and high pressures at idle when the clutch engages.
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05-18-2018, 06:06 PM
#8
Three Wheelin'
Thread Starter
Hi guys, cheers for your input !
Railmaster, yes the LWF is part of the issue, there is a few 993 rs with AC option, I am wondering if they have any issues...
my CCU is plugged to the ECU to control RPMs when AC is switched on, this is why the engine is not staling at all when slowing down into round abouts, slow corners, red lights ect ...
I guess as previously mention it may need more gass or as Griffiths mention it could be the pressure switch,
I will look at those first and review the mapping last, when everything is in good order.
Thanks
Railmaster, yes the LWF is part of the issue, there is a few 993 rs with AC option, I am wondering if they have any issues...
my CCU is plugged to the ECU to control RPMs when AC is switched on, this is why the engine is not staling at all when slowing down into round abouts, slow corners, red lights ect ...
I guess as previously mention it may need more gass or as Griffiths mention it could be the pressure switch,
I will look at those first and review the mapping last, when everything is in good order.
Thanks
05-20-2018, 12:20 PM
#9
Rennlist Member
From the factory, the Climate Control Unit is not connected to the Motronic engine control unit to regulate RPM when the A/C kicks in. There is indeed a connection from the CCU to the Motronic, this wire signals the need for heated air, and disables the fuel cut-off to avoid cooling of the heat exchangers when coasting or going downhill with low or no throttle.
On the Boxster/996, the compressor engaging was improved to avoid the RPM surge, the engine control unit then controls the compressor clutch.
It is normal to have the clutch engaging in 10-20 second intervals at about 20 degrees ambient temperatures. This behaviour is controlled by the CCU evaporator sensor only, to avoid having the evap freezing over.
Cheers,
Tore
On the Boxster/996, the compressor engaging was improved to avoid the RPM surge, the engine control unit then controls the compressor clutch.
It is normal to have the clutch engaging in 10-20 second intervals at about 20 degrees ambient temperatures. This behaviour is controlled by the CCU evaporator sensor only, to avoid having the evap freezing over.
Cheers,
Tore
05-23-2018, 06:05 PM
#10
Three Wheelin'
Thread Starter
From the factory, the Climate Control Unit is not connected to the Motronic engine control unit to regulate RPM when the A/C kicks in. There is indeed a connection from the CCU to the Motronic, this wire signals the need for heated air, and disables the fuel cut-off to avoid cooling of the heat exchangers when coasting or going downhill with low or no throttle.
On the Boxster/996, the compressor engaging was improved to avoid the RPM surge, the engine control unit then controls the compressor clutch.
It is normal to have the clutch engaging in 10-20 second intervals at about 20 degrees ambient temperatures. This behaviour is controlled by the CCU evaporator sensor only, to avoid having the evap freezing over.
Cheers,
Tore
On the Boxster/996, the compressor engaging was improved to avoid the RPM surge, the engine control unit then controls the compressor clutch.
It is normal to have the clutch engaging in 10-20 second intervals at about 20 degrees ambient temperatures. This behaviour is controlled by the CCU evaporator sensor only, to avoid having the evap freezing over.
Cheers,
Tore
Thanks for your reply, is it the case for the 993 RS with AC ?
thanks
05-24-2018, 02:19 AM
#11
Rennlist Member
All 964 and 993 models work like this.
Cheers,
Tore
Cheers,
Tore