Question---Thank you Roland,
This morning it was not that cold around 30 Deg F and the temp controller started OK, and I did the Diagnostic test as you suggested. The display flashed for about 15 to 20 Sec, and was showing AUTO FAN & MODE flashing 75F, then it stopped and was showing 36 F - No fault code was displayed. It normally takes about 15 minutes to start going out of control if it is a realy cold day- but in a warm day , the temp controller shuts down as soon as engine starts-
- Any other ideas
Thanks again for your time
Harry ----------------------
Followup To
Question -
Hello,
I have a 1994 Concord with automatic Temp Control.
Since two weeks ago, the controller suddenly goes in what it seems to be a default mode where it can not be controlled or shut down- In fact it looks dead, and has no indication- Even the defroster wont work. It gets reset if the car is sitting in the cold ( very cold) over night, but as the cabin warms up , then it suddenly goes to this "default" mode , where it pumps heat and fan is runninig in mid range , but heat can not be controlled of shut down.
-Is the problem the controller or the feed back sensor
- How could I test it ( except freezing the controller inside a fridge in a warm day )
- Where is the sensor located-
- Can I test the sensor - Ohm / resistanse reading
- Is it worth to buy a used / overhauled controller
- can I bypass the controller/ sensor for testing
Many thanks
Harry
Answer -
Hi Harry,
I suspect that you will have to run the diagnostic test quickly, before the unit goes into default mode. It sounds to me like an electronic component is overheating, and then it recovers when it cools down. But this may require some electonic trouble shooting to find it or at least to determine which part of the unit has the faulty component. But try to get a diagnostic code to read out before it shuts down.
Roland
Hi Harry,
There is fortunately some built-in diagnostic capability with the ATC type heater/a.c. units. If you will go to this site you will find out how to run the diagnostic test:
http://www.allpar.com/fix/codes-climate.html
Let me know what result you get back. I have info on the '89 ATC unit but it may not be identical to your '94 unit (the fault codes and procedure to get them chanaged between 89 and 93, whether the design changed I am uncertain). The sensor and its little fan are located behind the "Concorde" name plate above the glove box door. It serves as a grill for the fan opening. You could place a piece of tissue over the grill to see if it is held in place by the fan action, and if not then the fan and sensor may need replacement. On the other questions, I can answer based on my '89 manual, but let us see what the readout of codes shows before getting into those matters. Maybe the readout will allow us to fucus specifically on one aspect of the problem that is most relevant. So write back with any code numbers that come out. And if you have problem with the readout let me know.
Roland
AnswerThe fact that both the display and the funtion of the unit go out simultaneously leads me to conjecture that the problem is in the control switch unit itself, rather than a sensor or a power supply issue. You might want to remove the unit from its mounting and look at the plug-in and the unit's circuit board to see if you can find any loose or corroded connection and then turn it 'on' and see if any component on the board feels warm and also look for any signs of capacitors that have leaked electrolytic fluid (now dried),
I doubt it is in the wiring together of all other parts. Another thing to try, when it is exteriorized so you can get at the circit, is to buy a can of pressurized "circuit cooler" spray and apply it locally (with the "straw") to each major component on the board, one at a time, to see which, when cooled, causes the unit to return to a normal functioning. The spray has a high vapor pressure so it evaporates rapidly and will temporarily freeze the components. It should be available at an electonics supply store.
That component, once found, would be the one to look carefully around at its circuit board connections and seeing no problems then try to find a replacement for the that component.
Let me know if you find anything interesting.
Roland
