73 AC Wiring

[levix]

I just replaced all the engine side wiring harnesses, and now I'm trying to hook up the a/c properly.

[levix]

I don't know what the black 'pump' is in the first picture. It has two terminals (A) and (B). What goes to these?

I'm assuming the two terminal wire (C) goes to (D), but I would like verification. Also which way should it be connected?

(G) / (H) are obviously bulkhead connectors, and I just happen to have 2 open slots in my harnesses. 1 in the NSS and 1 in the engine. Again which one goes where?

The previous setup had (I) / (J) connected and going to one of the terminals on (D). Perhaps now (I) / (J) go to separate connectors (E) / (F)? If that's the case what goes to what?

[rudyjrusa]

I don't know what the black 'pump' is in the first picture. It has two terminals (A) and (B). What goes to these?

I'm assuming the two terminal wire (C) goes to (D), but I would like verification. Also which way should it be connected?

(G) / (H) are obviously bulkhead connectors, and I just happen to have 2 open slots in my harnesses. 1 in the NSS and 1 in the engine. Again which one goes where?

The previous setup had (I) / (J) connected and going to one of the terminals on (D). Perhaps now (I) / (J) go to separate connectors (E) / (F)? If that's the case what goes to what?

looks like a ac unit from classic air - i though about replacing mine with classic air system - i guess they do not have good instructions on hooking up ac wiring?? 

[levix]

Did some more research and the 'pump' in the picture is actually the receiver / dryer. The two terminals are for the high / low pressure switch.

In most modern A/C systems a pressure switch is used to shut down the system if high or low pressure is detected.  This can happen If the system malfunctions.   Pressure will build up and can blow a hose off venting all of your expensive refrigerant, e.g. the condenser fan fails.  Low pressure happens when the refrigerant is low.

Still not sure on the installation, but getting there.

[Nacho-RT74]

C goes to A/B , but you have unmatched prongs and plug. Its just about diff kind of plug or pressure switch at dryer. You can simply change the switch to match the plug, or change the plugs and use individual plugs to each prongs. No matter where conects.

G/H as rudy told... you need just to match your bulkhead wires... check on back of bulhead if you want but USUALLY blue ( compressor signal ) goes to engine harness plug and green ( blower ) goes to NSS harness plug

D is not an original device. it can be a thermostat switch, used when removing EPR valve on back of compressor when changing R12 to R134. Senses Gas lines temperature wrapping that iron wire around the inlet gas line and deactivates the compressor when its too cold to save the gas from freezing. Check CLASSIC AUTO AIR website about that... HOWEVER I never have needed that ( already changed to 134 and removed EPR valve ), maybe because living on tropic, will never freeze LOL. This switch must be hooked from somewhere in the compressor blue wire to deactivate the compressor, just like the dryer pressure switch. Just cut the blue compressor wire at the closer point of the switch and attach two prongs to hook this device, no matter which prong. Maybe you could need to elongate a little bit the wires. OR you can plug the E plug there and then run the I wire to this D switch. will be the same just won't need to cut your new AC harness and just elongate the I wire up there. there are MANY WAYS to make this, as you want.


We can say the compressor will be deactivated in both situations, running out of gas ( dryer pressure switch ) or gas being freezed ( sensed by this posible thermostat ). So the blue wire will go through BOTH switches and power wil be cut at any of this two situations. Be sure of course its a thermostat switch first, but once agan I never have needed that.

I-its the compressor clucth wire and the final destiny of the blue wire ( E )

F- blower wire.

J-its an iddle solenoid. Its used for many options. Some ppl ( and factory did ) feeds this solenoid from the positive field Dark Blue of the alt, to open throttles at iddle just when you turn on the ign key. When you turn off the key will close the throttles to save engine from "dieseling"... HOWEVER another option is to hook it also from the compressor blue wire to increase iddle when Compressor clutch engages and get back some RPMs lost on the AC engaging


I hope everthing of this sounds clear

[John_Kunkel]

Not sure what brand A/C you have but the thermal switch (D) is usually setup so the capillary tube can be inserted into the evaporator core inside the car. Is it just a different compressor on a factory system?

Do you have instructions for the switch?

[levix]

D is a preset thermal switch. In fact this one. CAA's install guide has the left side (closest to the capillary tube) going to one side of the hi / low switch although I don't really think it matters.

Not sure what brand A/C you have but the thermal switch (D) is usually setup so the capillary tube can be inserted into the evaporator core inside the car.

It's CAA (Classic Auto Air) and googling told me that you are correct.

Is it just a different compressor on a factory system?

No the car didn't come with A/C originally--at least looking at the old bulkhead.

[1973rallye]

Has not been a lot of activity on this topic for some time. Will take a chance that someone is still monitoring. I found topic this helpful as I have the same CAA system.  Question. Does this system utilize a water valve? There is no mention of one in my CAA instructions and if not I am puzzled on how to connect my AC control cable that runs through the firewall to what was the water valve. BTW my car was originally an AC car but everything was stripped so I am starting from square one. Thanks for any help. Ray