Is it possible to access the connections on the evaporator without removing the dash? The reason I am asking is I put a huge can of R-134 in and I could hear it escaping, and now it has zero pressure, and I just find it difficult to believe that the evaporator could be that deteriorated. I am wondering if maybe somebody replaced it and didn't hook up the connectors properly or maybe there is a damaged o ring. I would really like to rule this possibility out before taking the time to remove the dash.

 

The connections are at the firewall on the passenger side.

 

So I should be able to check them by taking the plastic cover off the cowl? That would be nice! That might acutally make sense, becuase I could hear the freon escaping both by listening through the center vent, and trough the air intakes on the cowl. If it was the actual evaporator leaking I don't think I'd be able to hear it from outside the car. I will cross my fingers anyway!

 

I am so used to my Mercedes which has a double firewall, I now see that removing the cowl does nothing to access anything. Are the lines going to the evaporator the 2 that are more on the drivers side? If so, how do I remove them from inside the engine compartment? It looks as if I should press in on the plastic tabs and pull, but I tried and it didn't budge. It does seem like these lines are loose though, I could move them around quite easily. Hopefully that's where the leak is!

 

Assuming the 850 engine compartment looks like the V70, I think this post will help you... https://volvoforums.com/m_62590/tm.htm
The second picture highlights the two lines running to and from the evaporator. In words, the lines are on the passenger side with the evaporator sitting behind the floor of the passenger side/glove box/etc. If the 850 connections are the same, these connections require a "spring-coupler" tool to separate them. I wouldn't try to separate them unless you are sure there is no refrigerant (freon) remaining in the system (or you are prepared for a blast of dangerously cold gas blowing out).