A/C Amplifier question

[James T]

Hi all
I am working through the non working bits on an 89 7MGTE MA70 GT. The car has had an engine replaced and some of the wiring never seemed to find the right home.
The A/C does not work when the dash button is on even though the light is on.
I have had the A/C gassed and can activate the magnetic switch manually from the battery. The 20 amp fuse in the passenger kick panel is okay.

I have used a Factory Manual PDF for a 1990 to track through the system circuit. The A/C amplifier pins 2 and 10 should have 12v when the button is in the 'on' position, (lit up) & 0 volts when off. I have the exact reverse!

Does anyone know if the 89 and 90 systems differ this much. I cannot see how this would work.
All help appreciated.

 

[sharpsupra]

i believe the fuse in the kick panle should be a 10 amp

 

[James T]

indeed you are correct sharpsupra! the relay block number 4 shows a 10 amp. will change that over. i have found many not quite right issues from the previous owner.

Any thoughts on the A/C switch returning zero volts when turned on?

 

[sharpsupra]

check out this website.....http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AC&P=15

 

[James T]

Cheers sharpsupra. I have actually pulled the entire PDF before. This is the one I have been working from. I am missing a connection from the A/c amplifier to the magnetic relay, however, my problem is that the power going to the amplifier is only 12 volts when the switch is off. When I turn the switch on I get zero volts. I have decided to hand it over to the pro's & booked in with an auto elec. I can rig a connection myself but the A/C will come on with the button in the off position.
80's electric! got to love em.

 

[sharpsupra]

i hear ya...sorry im not much hayulp lol...still havnt figured out my ac issue.

 

[James T]

All fixed! turns out it was the thermistor in the air box! No signal no A/C