I thought it would be simple enough to replace the temp freeze switch, but of course not !

You will see from these pictures that there is more than one thing in the temp freeze switch area, some I have no idea what was done.

The principal thing at the moment would be with the temp freeze switch differences. From the new part number it should be the same, but not exactly.
I am not sure if it will be long enough first and second when I insert the prong into the tiny hole which goes into the "evaporator"/mini radiator inside the dash.
Second the external prong in which the temp freeze wire goes into seems to be a bit small for that new wire to fit in, should I file the wire a tad to make it fit ?




Deffective temp switch




Where the wire goes into the dash area




New and old part different length of wire !




New and old temp switch




New temp switch box.




All these wires seem to be bridged !




The bridged wires seem to go into the hood and not to the blower on the passenger side as I first thought<br/>




this connection seem to go nowhere, when they should go into the hood I think with the round cap you see in the other pictures




Some writing on these but I could only make out the word brown




Cap which goes into hood<br/>




End of wire going nowhere after cap.<br/>




Hole for cap, everything seems connected in there ?

 

Here is something which doesn't make much sense in my book. When I installed the new temp freeze switch all I get is hot temps even with the AC depressed and I see no liquid flowing in the window on the front container. When I put the old one back in, I get less hot air, but not cold as should be and I see the liquid flowing in the container up front and there are NO bubbles.

I hope I will not have to spend the summer with no AC !

 

A working freeze switch will stop aircon compressor only if triggered by ice on evap. I doubt it's the problem, especially as you imply the probe won't reach!

What did you test initially to diagnose bad freeze switch?

Have you followed 12v supply to clutch through freeze switch, low pressure switch and connection to clutch?

 

The prong seems to reach the evaporator since it get tight at one point. I did not test anything since I'm not sure how to test it and what type of results that I should be getting if good or bad.
I took the suggestion from another rennlister in another post as a reply to my problem and he had the same issue, so I figured, must be that ! Well now I look pretty stupid, live and learn !

Where to place the volt meter connectors is usually my issue, I am not good in electricity/electronics.
The compressor was engaging prior to changing the temp switch since I had cold air coming out for a while off and on.

Not sure where this connector you are talking about is ?

Thank you for the reply.

 

The "wire" for the temp sensor is a capillary tube with (I suspect...) a silicone fluid inside. The fluid chenges volume with temp changes, pushing on the brass diaphragm and ultimately actuating the electrical switch. Bottom line: do not file or otherwise "adjust" the tube, and be very careful not to bend it to the point of fatigue or to kink it.

 

If the compressor was engaging then the freeze switch is ok, or at least the switch is closed which it should be unless the capillary probe detects ice. I had fun testing mine with tube dunked in iced salt water, switch out if water but checking with ohm meter that contacts opened when probe in ice water.

A freeze switch failure would be either always open, or as in my case corroded contacts so it had continuity but would not pass sufficient current to engage compressor clutch, shown by volts dropping in output side to way below 12V

 

So the voltage I am supposed to measure is at the connectors on the temp freeze switch ? Or do I have to check this voltage at another connector near the compressor, which I have no idea if there is one down there ?

What does this do ? The reason i ask is because this device goes all the way up when the AC is fine, but descends and goes back up by itself without chaning the settings, what would this depend from ?
29 928 573 150 03 control mechanism

 

Get a test light, and follow the 12v from the head unit to the compressor.

 

Andre that is the temp setting motor. It mixes heated air with outside air by moving an arm connected to flap on heater box.

If your compressor works then no need to look at power chain to compressor for reasons why you're not getting cold air. Focus your checks on:

Is the aircon refrigerant level correct (but if it was very low the compressor would not run - it would not get power from via low pressure switch that is next in power chain from the freeze switch.

Your temp control independent of the aircon system. This involves checking the various vacuum actuators, the temp control "string" of resistors (int temp sensor, ext temp sensor, temp slider and microswitches), the setting motor you asked about.

Adrian

 

Thank you Adrian, I will have to verify the sensors for sure and the microswitches and so forth.
I thought the setting motor would go hand in hand with the AC, but from what I understand it just works the flaps ? I know I currently have a problem with the mixed air actuator, no vacuum, but the AC worked even if I had that issue.

The freon seems to be ok, since with the old/current temp freeze switch i could see the white liquid flowing fine. What I found bizarre is when I installed the new temp freeze switch I could no longer see the liquid flowing ?
I might have to remove the head unit completely to confirm that all is ok inside.

 

If you're not seeing refrigerant circulating than the compressor is not running. Can you confirm by visual check of compressor pulley?

The new freeze switch could only cause this if it's faulty and open circuit, or you have not connected terminals or crossed the spade connectors.

 

I find it difficult to see even with a flashlight wether the pulley is engaging or not. When I look it always seem like it's moving, this of course is from the hood side. Would it be easier to check from below ?
OI gather the pulley must always turn since the belt is attached to other pulleys which turn all the time. Not sure where to look exactly on the front of the compressor, is the clutch the part between the pulley and the compressor, or is it built inside the pulley and the only way to see if it's engaging is from a front position ?

I guess my new temp switch was defective since I did connect the terminals correctly. When you face the rear of the switch in it's proper position, the left terminal should have the the blue and yellow wire and the right one should have the purple and yellow. I have connected them in the same manner on each temp switch.

 

Should I be checking the clutch drive plate for movement ?

 

When you install the capillary tube in the guide tube, should the capillary tube be all the way inside to the tip or should it extend pass the tip ?
How important in that guide tube, I have broken some lenght of it while trying ti push the capillary tube inside because it was so tight.

Also how deep should the guide tube go into the evaporator or the capillary tube if it extends pass the guide tube end ?

I am not even sure that the guide tube should be touching the evaporator as per one of the pics in this forum in which the capillary tube was extending pass the guide tube end and the only portion which went into the evaporator was the capillary tube and not the guide tube.

Maybe I am using the wrong terms, can someone confirm if my terms as per the pic is correct:

 

Thanks to Sylvain. Turco

I finally know what are my issues after testing a multitude of things from low pressure switch, compressor, temp freeze, head unit and sensors, internal and external.

The last PO had added two resistors in parallel to add more resistance, he thought, in a bypass of the internal sensor.

Head unit in general is working good, except my potentiometer which controls the temperature goes a little wonky sometimes, the resistance is all over the place instead of gradually going up if temp goes up and gradually go down if temp goes down. So I will replace the system board with a used one which we know works and that will be the end of that.

Temp freeze switch is also defective, after bypassing it, all works !
External sensor defective
Internal sensor works.
Compressor works fine.
Low pressure switch works fine.
One of my horns is toast.
One of my buttons on the sliders on the head unit is broken, the other one was replaced today by Sylvain and now like new.

I will retry the new temp switch to see if that one works, maybe I tested it wrong.

There were a multitude of things wrong, so very difficult to troubleshoot.
But again thanks to Sylvain, Turco, we have pinpointed the issues.

With the bypass on the external sensor and the temp freeze switch the AC is ice cold !

Until I can acquire all those parts and find the time to fix those issues I will keep those two bypasses in line so I can have some AC.
Tomorrow I hope to retest the new temp freeze switch to see if any better and if it's no good then I will return and get a new one.