fj62 a/c

[Vortec62]

I am in the process of hooking up the A/C on my Vortec powered FJ62. I
think I located the A/C clutch wire but it doesn't come on when I turn on
the A/C button. I started looking at wiring diagrams and tracing wires and
I can't locate the connector for the pressure switch. Where is it located?
Unfortunately I took the A/C apart several years ago and can't remember
where everything was. I was also wanting to trace the thermistor wiring but
I think the thermistor is in the evaporator under the dash...is this
correct?

I have a local shop cleaning up my condenser and I bought and mounted a new
receiver/dryer. I'm going to see if they can rebuild my vortec A/C pump and
then they will make some custom lines for me and charge the system. I'm
trying to get the wiring figured out for them.

 

[cruiser_guy]

I think the pressure switch is also in the evaporator casing.

 

[Lost_crusiers]

The switch is "conveniently" located in the pastic box that holds the evaporator. There are a few clips and screws that hold it together and the switch points to the rear on the passiger side. It is easy to figure out just a PITA to get to. You are rith about the locations of both items. It is not fun but neither is driving in 100 deg F. JL

 

[Vortec62]

Well this may be good news for me. It means they are still hooked up. I don't know if they are working though...seems like my compressor clutch wire should have come on when I pushed in the A/C button though ???. The clutch is controlled by the A/C amplifier...what are the conditions required for the it to engage the clutch? Does there need to be some minimum pressure in the system? My system is still open...maybe that is why the clutch wire doesn't come on. Tomorrow I will try connecting the two pressure switch wires together to see if the clutch wire turns on. Anyone have any other diagnostic tips or tricks?

 

[cruiser_guy]

Do NOT try to run the A/C compressor without freon. You WILL ruin it. It's designed not to operate unless there is sufficient system pressure and the engine detected to be operating (that's the wires to the coil) and the fan is running (there's a lead from the fan relay).
I hooked my A/C up on my BJ60, took it in to be charged and it worked. That was a retrofit using an A/C system from an FJ60. I did not attempt to "test" the wiring prior to charging to avoid damage to the system.

 

[Vortec62]

I actually don't even have the compressor in the truck at this point. I am just trying to get the wiring ready. This morning I jumpered across the pressure switch wires and then turned on the A/C button...I got voltage on the clutch wire

This leads me to my next question...How does the pressure switch work? Right now it seems to be open at no pressure. Seems to me that it should be closed at no pressure to make the compressor turn on.

 

[cruiser_guy]

A/C systems always have about 60 psi in them even when not operating. It'll run up to over 120 psi when operating on the discharge from the compressor. The pressure switch needs to open on a pressure drop to protect the system from operating dry.