NEW 134A AC ORFICE, WHERE DOES IT GO 89 740GL? Topic is solved

LASVEGASCRUISE · Post by **LASVEGASCRUISE** » 03 May 2005, 20:25

ANYONE GOT A CLUE WHERE THE AC ORFICE IS FOR AIR CONDITIONING?

THANKS

LASVEGASCRUISE · Post by **LASVEGASCRUISE** » 24 May 2005, 21:26

I THOUGHT SINCE NO ONE RESPONDED TO MY QUESTIONS THAT IT MAY BE A LITTLE TOO COMPLICATED. I DID FIND INFORMATION REGARDING THE REPLACEMENT OF COMPRESSOR, ORFICE, ETC. PROBLEM IS THAT IM NOT GETTING POWER TO THE COMPRESSOR WITH THE AC ON. I CAN SUPPLY POWER TO THE COMPRESSOR BY MEANS OF SUPPLING 12 VOLTS AND THE COMPRESSOR WORKS.

I'M CONFIDENT IN THE REPAIRS MADE SO FAR, NOW ITS ELECTRICAL TROUBLE. GO FIGURE. ANYONE KNOW WHERE THE YELLOW/BLACK WIRE GOES TO IN THE DASH FROM THE AC RELAY TERMINAL BLOCK. THIS LEAD WHEN TESTED WITH A TEST LIGHT MOMENTARILY LIGHTS THEN FADES. I BELIEVE IT IS ONE OF TWO VOLTAGE SUPPLY SIDES TO THE RELAY. NEED TO GET A GOOD WIRE SCHEMATIC....ANYONE KNOW WHERE TO GET A SCHEMATIC OF AC WIRING FOR A 1989 740GL?

LaRy · Post by **LaRy** » 25 May 2005, 11:54

Hi, most probably you will find the electrical drawing in Haynes. I have an electrical drawing for 740, 1986, and in that one I can find yellow/ black wire going from the AC relay connection #4, the coil. The other end of this wire is going to the function selector connection #F. It is a complicated connection. It is a lot of resistors and other stuff on the other side of the relay coil. I do not know how far you have come in your modernization, but between the selector switch and the compressor it is a pressaure guard, and normally in an AC system this guard is disconnecting the compressor if you have under / over -pressaure.

pageup · Post by **pageup** » 26 May 2005, 23:10

Whoa man...
This is AC 101 subject for low freon situations in cars.

Look at your receiver / dryer on the right side (firewall) of the engine compartment. The receiver/dryer is an aluminum tube about 4" in diameter maybe 10-12" long with a couple of hoses attached to it.

There is a pressure switch there too. The pressure switch will have 2 wires going to it. If your freon/R134 is low, then the pressure switch will open to protect the compressor from destroying itself.

If you're in the process of recharging, then you need to remove the plug from the back of the pressure switch, and put a jumper wire between the two wire connectors there to get the compressor to start running again.

Once the system is pressurized correctly, you can plug this thing back into the pressure switch and all is good.

(Provided you've properly evacuated the a/c system of all moisture...)