Air Con concerns

Started by AlfaACT, November 11, 2020, 11:55:00 PM

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AlfaACT

Seeking advice on the air con plumbing in an Alfetta coupe:

There are several matters I would like to resolve, so one at a time.

First: Is this a standard heater tap (for an Alfetta coupe)?

AlfaACT

2.   The Heater Tap pipe

The heater tap has a small pipe emanating from within it that follows a circuitous path then disappears into the heater box. The other end is not attached to anything, and is not anchored. It just lies between the heat exchanger and the fan motor.
First photo shows the heater tap & pipe in detail, the second shows the route the pipe takes.
Q: What is its purpose?


AlfaACT

3.   Spurious pipe #1:

This thin copper pipe runs across the gap between the inlet and outlet for the A/C pipes. It is embedded in the brass fitting at 1 and is tightly coiled against the second pipe at 2.

Q: What is its purpose?

AlfaACT

4.   Spurious Pipe #2:

Another thin copper pipe that traces a route across and along the heat exchanger – but this one is not connected to anything - at either end!

The end labelled "Start" appears to have been cut with "side cutters".

Q: What WAS its purpose?

AlfaACT

5.   Should these spurious pipes be connected ... ?

Q: Should the stub at 1 be connected to the "cut" pipe at 2?


AlfaACT

I should have said, these were all exposed as I had to remove the cabin fan to service it! Ouch.

In anticipation of lots of useful and interesting info - thank you.

OO=v=OO

bonno

#6
Hi AlfaACT
A simple answer to your questions is that it’s a TX valve for your car Air Condition unit. This TX valve controls the temperature and forms part of the A/C system. The cut capillary tube shown is part of the TX valve that has been replaced previously. The heater tap shown looks original or OEM replacement. I have attached a Youtube video that explains the purpose and function of the TX valve. that might better explain.
https://www.youtube.com/watch?v=oSLOHCOw3yg

AlfaACT

Thanks bonno,

"The cut capillary tube shown is part of the TX valve that has been replaced previously." That makes sense!
The video is informative and helpful too.

One (last?) question:

The subject of my Post 3 (the A/C's TX valve) is clearly fundamental to the function of the A/C! I get that now.
But why a TX Valve embedded in the heater tap? See my Post 2.
Does it override the operation of the tap - maybe so that you cant turn the heater "on" if the A/C is "on"?

The heater in this car has always either been fully ON or fully OFF! There was no fine control for heat.
The only way to control cabin heat was manually turning the heater on and off  - i.e. repeatedly sliding the hot/cold lever.
Therefore (sorry, another question!) does this mean that the TX Valve in the heater tap is non functional ???

bonno

My understanding of the older style A/C systems, the heater valve is simply a tap to supply water from the cars cooling system and is not tempt controlled. The purpose of the heater apart from warming the car in winter,  is to when combined with the A/C system is for defrosting the windows. As Sportiva has indicated the A/C temperature is regulated/controlled via the thermostatic switch which incorporates a sensor capillary attached to the evaporator to enable cycling on and off.

AlfaACT

As Sportiva mentioned, there is also a third thermo sensor - attached to the A/C cabin temperature switch.

The first photo is of the general layout of the inside of the upper section of the A/C box.

The second photo is a close up of the sensor attached to the back of the temperature switch.
Note the coil of the sensor (1) in front of the air outlets to the cabin and the dash.

The purpose of this sensor, given that it is attached to the thermo switch and primarily located in the air stream to the cabin, seems to be to detect the temperature of the air pushed into the cabin - i.e. the climate control component of the system?
 

AlfaACT

No argument Sportiva. The route of the capillary is definitely not correct, but I am having trouble identifying an appropriate route.

See attached pic:
I have removed the capillary from the small square hole that it poked through before. (cf post above)
Things to note:
1: square hole; (no capillary!)
2: second square hole;
3: inlet for fresh (external) air; (closed in this pic)
4: inlet for cabin/interior air (recirculation mode). 

AlfaACT

Reconstructing the interior of the A/C box is shown in the following sequence.
(Note: as the heater & A/C control switches are in the upper half of the A/C box, the photos are looking at the top of the box, but from below)

First is a separation plate: separating incoming air from the heat exchanger.

Note that the marked/starred positions indicate where tabs on the plate actually insert into the square holes in the A/C box - shown in the previous post. When the plate is properly in place, there is no room for a capillary to poke through!

AlfaACT

Next is the (upper) half of the fan cowling.


AlfaACT

Next is the (lower) half of the fan cowling ...

A point to note here, is that as the interior of the A/C box is assembled it effectively creates a wall between the switch area and the heat exchanger.

AlfaACT

Finally, is this a possible arrangement for the problematic capillary tube ... ?