1984 300DT A/C problems.

[HuskyMan]

I thought the system was discharged (wrong). I went to install a new expansion valve this past weekend, as I began to loosen on of the expansion valve bolts, green colored spray blew on me and the floorboard (fortunately I had the carpet out of the car!). So, I quickly retightened the bolt and the spewing stopped.

The A/C blows really hot on all settings. I checked the compressor, it is coming on. I checked #8 fuse, it looks good. Next is the mono valve and climate control. I have a multimeter and need to know how to properly check the monovalve. Also, does this car have a relay that might be causing issues?