1994 HZJ75 Troopy. New here! Air con questions (1 Viewer)

[SunnyTheTroopy]

G'day from the other side of the planet! I just bought the dream vehicle, a 1994 1HZ Troopy with a pop top! She's already been named Sunny, by my partner and we could be more excited to have this adventure vehicle!

I am learning about A/C systems in this vehicle as I want to get it running again, but I am a complete novice, so I am looking for advice. It looks like all the hardware is installed by the previous owner (compressor, switch, condenser, evaporator, dryer, all the lines are there, so I suspect the expansion valve is in there), but the wiring seems a bit off. The switch on the dash seems to work (it doesn't light up though) but the wiring in the engine bay is disconnected.
The first question I'd have is where does the compressor relay usually sit? (Engine bay or under the dash?) and can it be replaced?
Where is the Thermostat (and thermostat wire) located?
Also is it possible to get replacement plugs for the compressor and drier? Or do they connect directly to the relay?
Finally, what is the amplifier?

 

[LutherLM]

Beautiful troopy!

is the ac system full? I would start by checking the volume. because of this, the pressure sensor will not trigger the ac.

 

[Felde]

Hi
There are two AC systems: With amplifier (control lever in dash) and simple on/off (button in dash).
There are also two refrigerant versions: R12 (old) and R134 (new, less ozone harmful). Those can usually be told apart by indication on the compressor or the filling connectors.
Which one do you have?

All my further indications are based on my 1985 BJ73 with simple AC on/off.
The electric circuit basically works like this:
1. Main power is provides off the blower switch. AC only works when blower is on, in order to prevent icing.
2. Switch AC (either the AC on / off button or the amplifier) I understand you have the button. I assume, it should light up if engsged AND the blower is on. Other the bulb may be blown.
This sequence of two switches provides positive power to the relay actuating (coil) side.
3. The compressor relay. On my truck it sits on the firewall. Not sure this is factory though.
4. The pressur switch. It safeguards the compressor from running without refrigerant, as the refrigerant also lubricates the compressor. It sits in the negative (ground) side of the relay's (coil) circuit. If pressure is ok, it switches the relay actuating circuit (coil) to ground. On my truck it is located next to the condensor near the radiator.

So, this sequence of three switches completes the actuating (coil) circuit of the relay.

5. The relay's load circuit gets main power from the battery. There should be a fuse in this line. I can tell, mine is not factory. No idea where exactly the fuse would be located and how the wiring works factory side. The relay powers the clutch on the compressor.

I would start like this:
If you think your AC is factory: Get a wiring diagram (in FSM maintenance manual). Check handbook / manual tread on top of the ih8mud J7 chapter if you don't have one yet.

a) Trace back the wiring from the compressor clutch to find the relay. Utilize wiring color codes to work your way trough the factory harness, if needed.
b) Turn ignition on and check for positive power on relay's working (load) circuit input. If no power: Locate and check AC main fuse.
c) Locate the pressur switch and understand how it works. One line from the relay, one line to ground ( Usually near-by)
d) Check the actuating circuit of compressor clutch:
- Turn ignition on, but engine off.
- Turn blower on
- Turn AC on. (Light should come on. If not: Pull switch and check power-in, bulb and power-out).
If the system is charged, the compressor clutch should engage now with an clearly audible clack-sound.
If not, the system may be empty = pressur low = pressur switch does not engage. On a vehicle with inoperable AC, I bet, it is empty.
So:
- Pull the wires from the pressur switch and bypass the switch by connecting the two connectors. Compressor clutch may engage now.
If not: Check actuation of relay and check positive power to arrive on compressor clutch. If clutch has power but does not engage: Clutch bad.
The clutch magnetic coil is usually grounded via the compressor body, but there might be a cable, though.
On older vehicles, with AC inoperable for a longer period, the clutch also may be seized/ rusted solid.

The AC systems also features an idle-up somewhat somehow, but no idea how that exactly works.

 

[Felde]

Beautiful troopy!

is the ac system full? I would start by checking the volume. because of this, the pressure sensor will not trigger the ac.

Right. As explained, the pressur switch has two lines, which get connected to ground if the switch engages. So you can check on sufficient pressur by measuring conduction of the switch.
Older AC systems also have a viewing lens on the condensor where one is supposed to see drops of liquified refrigerant to appear. (Never worked for me, though).
Last measure is the AC shop to connect a d check / recharge as needed.

Good Luck Ralf

 

[TreadingLight]

The AC systems also features an idle-up somewhat somehow, but no idea how that exactly works.

On the hzj75s I have seen there is a vacuum solenoid mounted on the RH side, either on the fender / battery tray or on the intake manifold near the power steering reservoir. It sends vacuum to an idle up valve on the injection pump.

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