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Discussion Starter · #1 ·
Hi folks,

This is for my 86Turbo. The air conditioning on my 86T worked extremely well. Even on the hottest day 100+ degrees it will cool you down. I remember reading temps from the dash at around the high 30s to low 40s. All of a sudden in the course of one day I get 55 degree readings and it is noticeably less effective.

Now, for your consideration, this system is completely original and has never been opened. There are no bubbles in the dryer window and this is the original r-12 freon. When I put the gauges on it, the readings are always exactly up to specifications based on the temperature and humidity. Any ideas?

I thought perhaps the expansion valve could be malfunctioning. Do they wear out? Thanks for any ideas.

John
 

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the deccicant bag may be dead.. they can only obsorb so much water/moisture.. after so many years you have to get a new reciever/drier. of course this means you have to recharge the system. it could be the expansion valve, as the pressure drop is not correct therefor no cold air.. but this should show up on the gauges. the compressor is kicking on and off like it should right? is it possible for some more details?
 

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Might be the how the "doors" are actuating ?

With mine I have a similar thing happen...poor cooling with the AC on at times...but if I switch it over to Economy I get real cool air....meaning that the air is cooling OK...just picking up a lot of warm air along with it?
 
G

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Discussion Starter · #5 ·
Thanks guys,

For the record, as near as I can tell everything works like it should. (Yes, I know that obviously, something is wrong.) A few years ago when I replaced the heater core I replaced all the vacuum servo units under the dash ($$$$OUCH!!!) as well as all the lines under the dash and hood. I was thinking that I had a vacuum leak under the hood and I am getting some mixing of heated air. However, when I first turn the key the vacuum motor pulls a vacuum and shuts off in ablut 10 seconds. Am I right to assume that the gizmo on the passenger side of the firewall shuts off the flow to the heatercore? If it does, does it stop flow with no vacuum or does it require vacuum to close the valve and stop the flow?

Thanks again for the ideas.

John
 

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If you mean the vacuum operated watercock near the back of the RH cam cover, then yes it does require vacuum to turn off water flow to the heater core.
That may seem strange to some people, but it means that a vacuum failure in the system will still allow demist/defrost in the middle of winter.

Is yours the manual or auto (climate control) aircon?
 
G

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Discussion Starter · #7 ·
Mister T,

Thanks. I think you might be on to something there. I have the auto system. Again, the problem is that everything works just like it should. I was thinking along the lines that this is a 19 year old valve and even if it checks out with a vacuum test it might still be allowing coolant to pass. Thanks again folks. As soon as I figure this one out I will post the repair.

John
 

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It is fairly simple to test the watercock vacuum operation.
Open the hood/bonnet and run the engine and aircon at a setting where heater icon on the LCD display is *not* on, like max cold.
Take the vacuum line off the watercock. You should see the shiny lever under the vac diaphragm, behind the heat shield, drop. Put your tongue on the vacuum line and you should be able to detect that there is vacuum.
If the vacuum is weak or nonexistant, take off the vac line on the electric vacuum valve on the vac reservoir (near the headlight) and put on a known-good test vac line and give it the "taste-test".

If still little or no vacuum, take one of the wires off the valve and see if you can hear or feel it click when you connect and disconnect the wire. You might need the engine off (but the aircon running) to hear it.
When the valve energises it switches vacuum to the watercock.

See how that goes.
 
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