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There are a couple of options: 1) Just above the starter, you will see where the original cables go through a rubber grommet/bung in the engine tin. If the engine were out of the car, you can remove the original red cable and route the cable as per original. 2) If the engine is in the car. you can make an additional hole in the engine tin just above the top of the oil cooler. This piece of tin is removable for making the hole. Behind this piece of tin, there is a grey fibreglass oil cooler duct which is separate to the main engine shroud. The hole should go through this part as well. The cable then passes through both parts into the shroud and 'appears' above the oil cooler. It ends up resting on a metal piece of the oil cooler duct. From there it is an easy route to the alternator. Use rubber grommets to protect the cable. You can leave the original red cable in place and connect the new one to the starter in parallel as per your picture.
- Last week
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mja joined the community
- Earlier
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I found the problem, it is very simple and a lesson in ensuring all documentation is read prior to install. for HV 400v systems, sig=1. sig was set to 0 meaning communicating to the compressor internal ECU with the retrofit ECU didn't work properly. This information was listed in the read me file in the firmware update but not in the install, test and setup pdfs for the system. Everything works as expected now.
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Julian started following 400v HV Compressor only turning on during Standby - SOLVED
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Hi there, I have been having several issues with the operation and control of the running of the HV Compressor (312V). I have been able to connect to the ECU, the communication error was due to some shorting wires at the back of the 4-pole audio jack, this has now been rectified. We are having some issues with getting our HV compressor to run, we were able to get the system commissioned with refrigerant but are having some very strange running characteristics at the moment, where the compressor only runs in standby mode, it runs at full speed even though the ECU says through putty that speed is at zero and the blower is off. In On mode, we have it set to High/Lo mode as we are unable to switch to Climate mode, I have had to power the condenser fan separately as the ECU won't turn FAN on. When I enter MOD=1, it replies with ok and when I check list it says Climate mode is selected, however when I run the ECU with AC on it says the mode is still High Mode. it seems to be stuck in this mode despite different mode selection inputs attempted. It seems as if the system parameters are set for a 12V high current compressor, such as the compressor current targets etc. Would you be able to send the firmware applicable for the HV compressor you supplied? (I believe it is air con Compressor DM34A1-B0201X 312V dc). This would eliminate this as being the issue. In an attempt to trouble shoot some of the issues I have played around with the voltage inputs of the blower sense voltage and even inverted the settings with both BLV=7 and BLV=-7 attempted, testing all the combinations. In none of these states will the compressor run in On state. It will only run in standby. Here is an example of the diagnostic data in putty when it is in on state and the compressor is NOT running: Here is an example of the diagnostics when the ECU is in standby (pulsing LED) and the compressor IS running: Here is the list of our current settings: Your help in resolving this issue would be greatly appreciated, Thankyou very much.
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How hot should the compressor get?
Jonny Retrofit replied to Alfa's topic in Electric Air Conditioning technical forum
Unlike the 911, your compressor is in the engine bay so the ambient is a bit higher. The red cables will heat since they are carrying a fair bit of current and this gets transferred to the board. The ECU uses automotive grade components rated to 105 deg C. -
Alfa started following Compressor squeak/high frequency noise on engine shutdown
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I ran the A/C with the car stationary for around 10 minutes, and all was well. The outside air temperature was around 37C and the system was giving 7C air output. When I turned off the engine, for around a minute there was a strange squeaking noise coming from somewhere around the compressor. Is this normal, due to the hot temperature, or does it indicate a problem? I could see anything such as gas escaping. IMG_3931.mov
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How hot should the compressor get?
Alfa replied to Alfa's topic in Electric Air Conditioning technical forum
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On the 993 suitcase you should still be able to place the evap sensor in the factory location for AC cars. This is to the left of the expansion block as you look in the trunk. Ideally the evap sensor is pushed between the fins of the evaporator. The factor sensor is a long spike but you could use a long metal tube pushed into the evaporator fins and then put the sensor in the tube. See here: The cabin temp sensor should go under the dash where the inlet flaps are. If the suitcase is still out of the car, you could also put the evap sensor at the back - again pushed between the fins.
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How hot should the compressor get?
Jonny Retrofit replied to Alfa's topic in Electric Air Conditioning technical forum
Yes, that sounds normal. The compressor motor windings are cooled by the refrigerant but the discharge port (the one on the top at an angle) will still be too hot to keep your finger on (around 65-75 deg C). Presumably when you say 'plastic top', you mean the ECU (black case with two red wires)? -
Alfa joined the community
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Just been testing the unit fitted in my Alfa and after a short run opening the bonnet I could smell "hot plastic" coming from the A/C compressor. The temperature of the plastic top was around 60C and the metal body around 57C. Is this expected and within normal range?
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Julian started following Problem communicating with Electrocooler AC ECU
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Hi There, I was hoping for some help with an issue I've been having while trying to set up the electrocooler ECU. In previous tests I have been able to connect to the ECU and Interact with it, like turning on the condensor fan by setting it to 1. I was also able to update the firmware to electroCooler_v1_17. However, when I was intending on getting the system commissioned, I tried to connect to the ECU via putty but was unsuccessful, the terminal page showed nothing. Then when I did a test to see if I could update the firmware in any way, the terminal FlashLoader returned the message "No response from the Target, The boot Loader can not be started". The image for this message is attached. I have checked the voltages on the black and grey plugs connecting to the ECU according to the manual, and the voltages match what should be expected. also when the AC button is pressed on, the LED button light pulses on and off, indicating that the AC system is on standby. When the AC button is pressed off, the system LED button Light goes dim, meaning that the Car is started, but AC is available but OFF. The fact that the led status light is still indicating a switch between these two modes makes me think that the ECU is still working fine and connected correctly, but the laptop for some reason is unable to communicate with the ECU. I have checked that it is the correct com port, set the correct speed of 115200 on both the putty settings and also set the com port to that rate aswell. I have double checked the rest of the retrofit profile settings I made for putty according to the instructions and all of this seems to be correct. I have also tried connecting with a different USB A to Audio jack lead but no success. Currently, we are not really sure where to go from here in terms of trouble shooting, so please any advice or information would be greatly appreciated, Thankyou
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Julian joined the community
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Chris Amond started following Where to put Temp Sensors (Porsche 993)
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Chris Amond joined the community
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Geoff Smith joined the community
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If the cabin is hot, it will effectively do what you have described. There is an alternative method to setup the temp sensor. Instead of putting the (yellow) cabin sensor in the inlet air duct, place it in the outlet duct on the blower. Then change the 'cabin' temperature setpoint (CTS) to the desired vent temperature (say 7 deg C). You will find that the compressor will run hard for a few minutes and once the vent temp is down it will back off.
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Our most frequent support issue is a non starting compressor. The majority of cases are either wiring problems or assumptions about how the system works. So let's start with some basics. No need to connect a computer to check any of the following: 1) Battery voltage. The compressor will not operate at all below 11V or above 16V. Please note that battery voltage checks with a DVM (digital volt meter) may not prove that you have sufficient voltage at the point of compressor start. For example, if you have a fully charged battery (above 12.6V) it is tempting to start the system without running the engine. Although this may work, the battery may also immediately dip and the compressor not start. It is alway best to start the engine. 2) Start up sequence. When the car ignition is switched on, the ECU must first see a battery voltage above 12.6V before the system is deemed to be 'Ready'. We use this to detect an engine start as we don't want the system to operate without the engine running (it would drain the battery). Below this voltage, the blue light will pulse indicating 'Standby' and the button will not respond to presses. When the system is 'Ready', the blue light will go solid (although dim). Now, the button can be pressed and the blue light will go bright - the compressor should now start although it may take up to 30 seconds. The contact relay will also click (you will hear this first). 3) Blower voltage detection. The voltage on the orange wire (connected to the blower) is monitored to detect if the fan is running. The compressor will not start if the blower fan is off (to prevent the evaporator from freezing) and the system enters 'Standby' (pulsing blue light). Some cars switch the 12V to the blower and some switch the GND. The 911 switches the GND so a voltage below 9V on the orange wire represents ON. If in doubt simply disconnect the orange wire to ensure 'ON'. This is the default setting (although it can be changed in the ECU software for fans that switch 12V - see BLV setting). 4) Blue Button/Switch. The button's blue light is controlled by the ECU, not by the button itself. It needs supply of 12V (red) and GND (black). If the ECU is not running of in the wrong condition (e.g. engine not started), the blue ring light will respond to button presses. This is normal. 5) The condenser fan is controlled by the compressor current draw detected by the ECU. Do not expect the fan to come on when you press the blue button. The system pressure needs to build, which takes more amps from the charging system which in turn switches on the condenser fan. 6) Battery and current monitoring during running. Once the compressor starts it will ramp up to speed. The speed of the compressor will be faster in hot weather. The compressor may slow down either due to current monitoring ( usually to maintain 75A or less) or because of sag in the battery voltage. 7) Idle setup. If the idle RPM is low, the battery voltage will also be low and then the compressor may stop. The ECU default threshold is < 12V at the battery for more than 1 minute. The compressor will then wait for 1 minute before starting. The worst test conditions for the AC are to leave the car to idle after it has been sat - get out and drive the car for 20 minutes to recharge the battery. Then, you can let the car idle and observe the battery voltage with the AC on. If it is below 12V, then increase the idle so it is around 12.5 or better. If you can't achieve that without a very high idle then check all the ground points and 12V high current cabling including alternator and starter motor connections. As a benchmark, all our alternators can put out 70A at an idle of 950 RPM on an SC. Note, however, that some earlier 911s have lower geared pulleys so might require a higher idle (or a pulley swap). These cars are meant for driving! The timers and control scheme in the ECU have been designed to keep the AC running in typical driving scenarios. If the compressor is stopping during driving you most likely have charging system issues. The above checks will get most systems running without a laptop using the default settings as delivered. If you still have issues, there is a more in-depth diagnostic procedure documented here.
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Manual cooling level/control possible?
Showdown replied to Showdown's topic in Electric Air Conditioning technical forum
Thanks Jonny, I think that's a completely reasonable and logical response! Perhaps coding it to allow the pump to run at full load for 5mins and then drop down to 70% (or some lesser, but still effective number) for 5 mins and then back up, etc... would be a way to get max cooling without overloading the system... I'm just thinking that there are times when I would want a full blast of ice cold air, and other times when cool air would be sufficient. Then again, 50 year old car! We'll see. Whatever I end up coding I'll report back. -
Well you could do that but... The whole reason we have the system do that 'automatically' is that we want to operate within sensible power limits. The goal of the ECU during any run of the car is to get to a stable state where the compressor is maintaining the cabin temperature to make it comfortable without operating everything at full chat. This saves on power (HP and fuel), reduces heat in cables, maximises the life of the pump etc. We setup at 21 deg C since that is a reasonable target in an old car with no insulation or UV tint. I would just be wary that if the system ends up set on 'coldest' all the time, the pump may always be on full load. Temp sensors are 10k NTC thermistors.
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