1993 Digital Climate Control Unit Help

Hoping someone can clarify the differences between the 1993 16157324 unit and the 16157334 and how interchangeable they are.

I'm presuming the 334 unit is for 92, since my 324 unit is from my 93.

I've been chasing a problem and pulled the 324 unit from a sedan in a junkyard, neither seem to work.

When my unit did work, it worked intermittently. It also had an intermittent problem where it would work but seemed to be running through a bench test mode, cycling through the various fan speeds and air settings. When it was doing this I could hear something like a relay tick/buzzing someplace else in the dash away from the unit.

Either way, I'm cracking both open this weekend to remove the cold solder and reflow by hand and look for obvious things like a bad capacitors.

I'll probably do both, starting with the 334 unit from the junkyard to get up to speed.

If anyone can clarify the difference (i'm presuming year and probably has to do with the trouble codes mode, but that's just a guess. I'd like to know if I can interchange. I'd also like to find a diagram of the boards if anyone has one or can point me to it. There's not a breakdown in the service manual on the unit itself.

Thanks in advance.

A friend in CA had a 93 wagon and the number's matched. If anyone has a parts book and can ID differences in the units or compatibility issues between the 92 and 93 sedan and wagon units, I'd like to know.

For me at least, a few days on my heels waiting for USPS and i'll be back to winter weather inside the cabin once again.

Thanks to Dan for helping out.