Adventures with A/C... how to test idle-up VSV?

[Grant]

I almost have my A/C system in, however I'm trying to check if the A/C idle-up VSV is working, and I cannot get the car to switch it on. I have verified that the VSV is working.

Does the car need to be running for the VSV to activate?
Does the compressor clutch actually have to be engaged for the VSV to turn on? (this would make sense since there would be no reason to raise the idle otherwise... right?)

I'm really just trying to double check everything before charging the system...

Thanks in advance.

[jondee86]

The A/C Amplifier appears to have a crap load of inputs, including some that
confirm the health of the A/C system and the engine status. So I think the chances
of getting the VSV to activate without a fully operational A/C system on a running
car would be somewhat less than slim

Cheers... jondee86

[negrizio]

Grant,
from my own experience rebuilding the 86 a/c system, I can tell that you need to use the wiring diagram. You must test continuity from-to the A/C amplifier. Also check the 2 relays, idle up cut relay and the compressor relay.

One of my issues was a faulty pressure sensor located on one pipe of the evaporator. The a/c amplifier uses lots of inputs as jondee86 says... including rpm signal, battery voltage, thermistor resistance, ecu signaling and compressor sensor signaling etc…

[Grant]

Grant,
from my own experience rebuilding the 86 a/c system, I can tell that you need to use the wiring diagram. You must test continuity from-to the A/C amplifier. Also check the 2 relays, idle up cut relay and the compressor relay.

One of my issues was a faulty pressure sensor located on one pipe of the evaporator. The a/c amplifier uses lots of inputs as jondee86 says... including rpm signal, battery voltage, thermistor resistance, ecu signaling and compressor sensor signaling etc…

Yea, I've been referencing the wiring diagram a lot. I checked the relays already, so I know those are good. I have not checked the pressure sensor yet, so thanks for the tip. I'm hoping it's fine though because getting the evaporator out is a pain in the ass.