Making A/C work

JP147 · Post by **JP147** » Sat Oct 17, 2015 11:25 am

When I bought the car, there was no AC belt and the previous owner didn't know if it worked. I got a belt and replaced the idler bearings, but still no AC.

There is gas and the pressure switch is closed, but there is no voltage at the pressure switch. I wired the compressor clutch positive straight to the battery and it engaged and blew very cold air.

Any ideas on what I should try next?

Post by **TOONGA** » Sat Oct 17, 2015 12:06 pm

Check the 3 relays on the drivers side firewall to see if they have power and are working.

As well check the fuse/s for the aircon and heater.

TOONGA

Proton mouse · Post by **Proton mouse** » Sat Oct 17, 2015 1:45 pm

Also check the relay and glass fuse are in place, that usually sit up, and to the left of the main cabin fuse box.

Silverbullet · Post by **Silverbullet** » Sat Oct 17, 2015 4:04 pm

If there is nothing at the pressure switch then it could be a few things; According to my factory A/C wiring diagram the current flowing through the pressure switch(es) flows in this order:

.85R fusible link > 20A fuse for blower > blower relay (N.O) > A/C switch (in cabin) > low pressure switch > high pressure switch > coil of the 6 pin relay (on shock tower) > thermostat (bolted to outside of evap box in cabin, temperature probe pinned to the evap core) and finally to earth through the 4 position fan switch (this circuit will not operate unless the fan switch is on)

So just check everything in that order. If the blower fan still runs then my money is on the 20A fuse which should be in its own holder on a wire near the fuse box as others have said.

YouTube · Post by **El_Freddo** » Sat Oct 17, 2015 6:22 pm

There could be too much pressure in the system. I'm 99% sure that the MYs and L's only have an over pressure switch. No low pressure switch.

If it blows super cold air it could be over pressurised, or a dead switch.

Cheers

Bennie

JP147 · Post by **JP147** » Sun Oct 18, 2015 3:51 pm

Thanks guys, I will check it all out tomorrow. I don't think it would be over pressurised since it hasn't been used for many years, but I will see how it goes.