3rd problem on this XJ6.

(First, no action at all, it was the fused ground wire on the left that had only one strand of copper, which meant I could measure there was a connection, but not that it was not enough for the system to work. New wire and fuse, fixed.

Second, only 2 fan speeds working. Jag-aire module fixed this)

Now I have an intermittent problem. Half of the time all works (no A/C though, no belt), fan speeds, direction, temp. But the other half of the time, I constantly have full heat as if the left control is at full heat.

My diagnosis so far:

-I don’t hear any whirr from servo, and I don’t see any of the rods moving or anything

-I’ve done the Sensing System Testing on page 6 f4rom Jag-aire

Pin 7 and 4, 0-9 kohm, check

Pin 7 and 3, 42kohm in Defrost and 15 kohm in Other, check

Pin 9 and 8, 2.16 kohm, check

Pin 9 and 5, 2.25 kohm, strange, because that indicates servo in full cool, but I get full hot air

Pin 1 and 2, no connection

The latter could indicate faulty servo motor. But since this is intermittent, a bad connection (hopeful &#128522? Where? Where/which fuse controls the whirring motor that works sometimes? Which fuse controls the servo?

Thanks

 

Development. I've found out the servo motor works, had to wiggle the wires a bit on the right side while using 9V battery on Red and Purple on the left side. I've also found out that using the 9V on Red and Purple, I can control the temperature, so that part works.
But why does the temp knob on the left then not work? It works as per test above ("Pin 7 (Blue wire) to Pin 4 (White wire). Temperature Selector should vary from 0 to 10K.", and my test showed "Pin 7 and 4, 0-9 kohm, check"). So the know works and the servo motor works.

My guess is that if this was normal cheap heater, that would be enough. But since this is an automated climate control system, there's a third component, a temp sensor and I guess a fourthe component, something translating the knob position (required temp) and the temp sensor output (actual temp) to what the servo motor must do to get me the needed temperature.

Makes sense?

 

Almost answered my own question now, fiddling with the 2 temp sensors, in upper dash pad and in right side motor, it now works.

 

Hope your climate control is continuing to work.

A couple of comments on your tests from the first post of this thread:

Pin 9 (O) to Pin 5 (G). Your reading is correct for the servo in full heat. Zero is full cool, 2k ohms is full heat. The Jagaire notes have this information bass ackwards

Pin 1 (P) to Pin 2 (R). This shows servo motor resistance. The servo is connected via limit switches and diodes. This is so that, if, say, full heat is commanded, the servo will spool to full heat mode and then disengage the limit switch so the motor is no longer driven in that direction. It will only move again when the amp commands more cooling. Hence you will see open circuit when metering out with multimeter positive probe on Purple and negative on Red. But if you reverse the multimeter probes, the servo motor will be connected via the diode, so you should get approx 30 Ohms that way. Similarly, when the servo is in full cool mode, you need to check with multimeter positive to purple and negative to red. The limit switches and diodes in parallel with them are illustrated in the S57 wiring diagram which makes this easier to understand.