1G A/C The air conditioner turns on hot

[IvanJashin89]

The air conditioner turns on hot. Eclipse G1 1993 2WD 2.0
This happens in random order. The air conditioner blows cold from the start, and when the car is restarted again, the air conditioner no longer turns on. Or the movement turns off. According to diagnostics, I discovered that the ECU with C65 does not output minus to the electromagnetic clutch relay. What can be wrong. I would like to clarify if anyone has information regarding the ECU, what exactly provokes the disconnection of the minus from C65 to the electromagnetic clutch relay. Sensor or something else

 

[1990TSIAWDTALON]

Is your a/c sensor in your thermostat housing good, no loose connection and working properly?

 

[IvanJashin89]

Is your a/c sensor in your thermostat housing good, no loose connection and working properly?

Yes, works correctly

The minus disappears precisely from the engine ECU. Contact C65 with the engine ECU stops sending a minus signal to the air conditioning clutch relay. It only starts working when the machine has completely cooled down. I would like to know what could influence this ECU decision. Temperature sensor, kick-down or something else. All manuals describe the minus output from the ECU, but there is no description for what reason it may turn off

 

[1990TSIAWDTALON]

@steve , do you know anything about the A/C circuit?
That was probably a dumb question......you are a valuable resource for our electrical gremlins

 

[IvanJashin89]

@steve , do you know anything about the A/C circuit?
That was probably a dumb question......you are a valuable resource for our electrical gremlins

I'm just trying to find an answer on various DSM forums in hopes that someone has had the exact same problem and similar symptoms. What if someone actually encountered such a phantom

 

[1990TSIAWDTALON]

That is why I tagged one of our forums electrical guru's (among others) to see if he has any advice.
Since you are new, you probably didn't know what I did.

 

[19Eclipse90]

Just to be sure, when this occurs, can you ground the wire going to ECU pin 65 and get the relay to engage and the system to blow cool again?

Based on descriptions I can find, it looks like the only condition for the ECU to pull pin 65 to ground is that the air conditioning switch is ON. But the air conditioning switch signal gets to ECU pin 7 by going through the A/C control unit, the A/C dual pressure switch and the A/C engine coolant temperature switch.

You do say that it stops blowing cold when the engine is “hot”. Do you know what the coolant temperature is when this occurs?

And have you measured A/C system refrigerant pressure when this occurs to ensure system is within operational range (210-2700 kPa)?

Semi-related post: 1G AC not working

 

[IvanJashin89]

The temperature remains stable in the middle; if you ground pin 65, the air conditioner turns on again as expected. The logic is that I can drive at 30 degrees and it will work uninterruptedly as it should turn on and off, all I have to do is turn off the car and voila it won’t turn on anymore. In this case, all the power to the relay is available except 65

Just to be sure, when this occurs, can you ground the wire going to ECU pin 65 and get the relay to engage and the system to blow cool again?

Based on descriptions I can find, it looks like the only condition for the ECU to pull pin 65 to ground is that the air conditioning switch is ON. But the air conditioning switch signal gets to ECU pin 7 by going through the A/C control unit, the A/C dual pressure switch and the A/C engine coolant temperature switch.

You do say that it stops blowing cold when the engine is “hot”. Do you know what the coolant temperature is when this occurs?

And have you measured A/C system refrigerant pressure when this occurs to ensure system is within operational range (210-2700 kPa)?

 

[19Eclipse90]

When this occurs, turning the AC switch off and back on doesn’t change the outcome?

Do you know if the issue still occurs if you bypass the engine coolant temp sensor on the thermostat housing?

Same question with the dual pressure switch. Though these are only tests.

How does the ECU board look?