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98 Neon A/C Issue

09-22-2010, 08:42 PM
I am working on a 98 neon 2.0 DOHC, the A/C Compressor won't kick on, I discharged, vacuum'd down the system and recharged and the compressor still will not kick on, jumped the Low pressure switch and nothing.

I removed the A/C compressor clutch relay and supplied power to terminal 87 and the compressor kicks on.

I d/c'd the Low Pressure switch and supplied ground to the DB/WT (which leads to the high pressure switch) and the compressor kicked on.

My schematics show this order of operation: HVAC Controls - A/C Cycling Switch - Low Pressure Switch - High Pressure Switch - PCM - A/C Clutch Relay - A/C Clutch......

Now I have no signal (Ground or Voltage) from the DB/OR wire, which comes from the A/C Cycling switch, of the Low Pressure switch...

so I think my problem is with this switch (which I cannot seem to locate) or the HVAC Control Assembly.

does anyone know where the A/C CYCLING SWITCH is???

Thank in advance

09-22-2010, 08:57 PM
I THINK I know what the A/C Cycling switch is, I think it is the Low Temperature Switch (PROBE in the Evaporator Core), which cycles the compressor OFF when it think the evap core is at or near it's freeze point.

I will check it out tomorow when I get to work.

Anyone wanna chime in, your more then welcome to.......

09-23-2010, 10:46 AM
Well, the Low Temperature switch is in fact the A/C Cycling Switch.

That wasn't the problem though, after do some more test I found the fuse (#8, 10amp), for the backup lights, in the fuse block on drivers side of dash, to be the problem.

This fuse also powers the "Fused Ignition Switch Output" to the A/C Cycling Switch (Low Temperature Switch, Evaporator Core Probe).

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