So I found issues with my A/C
1. Had no cold air went to check levels AC compressor was leaking, it was replaced, and fluid added to system. Still the system wouldn't activate. (this was a used A/C unit from Z1 maybe suspect as being bad)
2. Check ecu and pins 46 and 9 were sending and receiving ground
3. check plug F25 and there was no signal found.
4. Check main harness found it was resting on external wastage pipe and got a little charred assumed a problem wire (maybe more damage but can't get it out without removing manifold or tranny and tiling motor). Ran a new wire to harness after charred point.
5. Had signal on F25 but when plug connectected to E12 still A/C clutch was not a go. I tried to find what the problem was I wiggled the E12/F25 connector and at one point got connectivity to low pressure switch but only once (I think I have a bad plg and don't have tools to de pin connector) so I think I got an issue with the brown plug and the orange wire on the E12
6. Checked black-Green wire to AC relay good connectivity, checked orange wire to E12 (brown plug next to relay box) and had no signal.
7. Here is were I may have screwed up I ran the ecu signal wire directly to the orange wire before the low pressure switch. A/C system started working.
8. Going for a test drive I heard a large hiss thought it was coolant or something else but figured out it had to be pressure relief valve by the AC compressor itself.This is a 1990 300ZX that I converted to R134, even tho I replaced the drier at one point and got a new low pressure switch I did not ue the 94 switch that is dual hi/lo pressure switch (this would have probably) shut off the compressor and had not triggered the pressure switch. I don't have dual pressure switch so I can't tell what the high pressure was but using a cheap A/C recharge gauge kit I was able to see that the low side was borderline low. My questions are many
1. What can cause this high pressure (takes 520psi to blow that relief valve)?
2. Is there something between E12 and low pressure switch?
3. Can the ecu still be a problem even tho its sending a proper trigger to activate AC based on AC request from climate control.
4. Could the suction throttle valve be the problem? How can I diagnose this? Z32 wiki saids to check coils on evaperator but the car was blowing cold.
thanks in advance
signed
Sweating in the summer.
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