Original post regarding no cooling and the fix thanks to Brickboard help:

https://www.brickboard.com/RWD/volvo/1656235/940/960/980/V90/S90/ac_problem.html

The AC worked for about a day and then gave up. Jumpering the pressure switch failed to engage the compressor. Applying 12v directly to the compressor engaged the clutch and cooling began.

Some years ago I had a 91 745 with similar behavior and it was a bad solder joint in the control unit. The control for the 94 is the same. After digging it out of the dash I took it to the bench and opened it up. With a magnifying glass and strong light I could see that the joint pictured in the FAQ's did indeed look suspect.

https://www.brickboard.com/FAQ/700-900/HeatingAirConditioning.htm#MCCClimateControlACNotWorking

Reflowing that joint restored normal function to the system.

There are two tabs on the bracket that angle up on the bottom two holes of the control unit. They prevent easy extraction of the control unit making it necessary to remove everything above the ashtray to finally remove that bracket to free the control unit. I was going to cut off those two angled pieces before putting things back together but I forgot to do that. With those cut off it would be simple to remove the control unit from the dash should it ever again necessary.

"There are two tabs on the bracket that angle up on the bottom two holes of the control unit"
These two tabs are a problem but easy to deal with. Expose them and you will be able to bend them forward with a nail set and plier. Remove the controller and then bend them back and they will be out of your way forever.

Also, while in the area, route the wiring to make it easier to extract the controller a little farther before you have to disconnect the vacuum lines etc.
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89 240 wagon, 94 940, 300K, 94 940, 141K

blocked drain line?

>blocked drain line?

No, a cracked solder joint on the control unit.