1.When the AC works, I still get hot air out of the side vents. Not the case with my 93 190E 2.6. I'm guessing some sort of vacuum or switchover valve fault?

2. The AC has been intermittent but now doesn't work 90% of the time. The pressure switch seems fine, the system isn't low, I've replaced capacitors and resoldered the board in the KLIMA relay, but it's only gotten worse. Seems to not be a problem with the Tempmatic unit itself (I can certainly test with a known good one).Before when it sorta worked, it would typically cut out and the not cut back in under extended acceleration. Might be related but the tach works but will once in a while the fuse it is on will blow, and the cruise control used to work but currently doesn't. Any ideas of what would cause the AC not to run?

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

You're probably not getting a good speed signal to the Klima. The root cause could be a bad crank position sensor or a problem with the EDS control unit. Diesel 300 has written about recapping the EDS controller. And you can bypass the speed function by replacing the Klima with a couple of relays:

Compressor speed sensor.

I'm guessing the EDS is the ELR in my case? The three controller relays in the car are ELR, EGR, and KLIMA. EGR I've had unplugged. I can see three caps on the board, think I actually have some of the right values around somewhere, but the board is dirty as heck, definitely gotta resolder everything.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

Sounds right, EDS is for turbo only.