General A/C questions - missing some components

-
U

Uhcoog1

Well-Known Member
Joined
Feb 7, 2011
Messages
888
Reaction score
79
Location
Houston
I need to get my factory under dash A/C working with my sanden 7176 compressor and aftermarket condenser.
Currently I have:
1-Everything under the dash, though not wired, and vacuum lines not hooked up. 1973 Plymouth Duster factory dash.
2-Compressor
3-Condenser

I'm going to start working my way through the system this evening. Get the blower motor wired and running, and play with the vacuum system.

Questions I have that I wasn't able to readily find answers to:
What is it on the AC line near the firewall? The manual lists it as an expansion valve - what does it do?
The manual talks about the anti-freeze switch- where is that located?

That's all I've got for now for questions. I know I need a new drier, low pressure cut out switch, and custom lines. Anything else I'm missing? Bouchillon Performance sells an AC clutch cycling switch that they say is needed for a Rotary Compressor - I'm guessing I need one? How do I go about installing one?

Thanks!
Wade
 
What do you have for a manual? The factory shop manual should picture the temp switch

The expansion valve is the entire key to how and why AC works. It is the "restriction" that causes refrigerant to evaporate. WIthout it, all that would happen is that refrigerant would go round and round in the system.

The problem is, nobody seems to have a 73 manual, so I don't know the differences between a 72 and 74.
 
Got it! That makes sense.

I've got a 73 chassis manual.

Do I need to add a clutch cycling switch?
 
You CAN run without it. Depending on year, model, etc, you have several switches all in series to run the clutch. This is not necessarily specific to your car

1--the main dash control, obviously selects heat/ cool, and turns on that switch for clutch, if all others are "made."

2--temp control cycles clutch on temp

3--"freeze" control on evap if temp at evap gets too low, drops out clutch and allows airflow to defrost evap

4--low pressure control drops out clutch on loss of system pressure.

The simple "hang on" A/C I used to have in my RR was very simple --just a blower switch and temp control on the evap.
 
As I recall my 69 Dart, the factory AC had just a thermo-mechanical expansion valve on the firewall. It had a "gas thermometer" that stuck in a well in the tube after the expansion valve, a thin copper tube like you see on older gas water heaters w/ continuous pilot flame. That made pressure for the diaphragm of the expansion valve, making a simple temperature feedback loop - lower temp choked off the refrigerant flow, higher temp flowed more. I think the compressor was turned on and off by a temperature controller in the dash. Most classic after-market or dealer installed under-dash AC boxes use the same controls. Later A's added the low-pressure cut-off switch and such. Many Sanden's have a port on the rear head for a small pressure relief valve (PRV), which might be smart. I bought one for ~$8 on ebay for a Sanden. I think they pop ~300 psig.
 
BillGrissom;1970034241]As I recall my 69 Dart, the factory AC had just a thermo-mechanical expansion valve on the firewall. It had a "gas thermometer" that stuck in a well in the tube after the expansion valve, a thin copper tube like you see on older gas water heaters w/ continuous pilot flame. That made pressure for the diaphragm of the expansion valve, making a simple temperature feedback loop - lower temp choked off the refrigerant flow, higher temp flowed more.

I just replaced that expansion valve on my 72. It was $28 at Autozone. Easy install too :)
 
You must log in or register to reply here.
-

Back
Top