My AC is leaking. I put some dye in and don't really see anything under the UV light under the hood. I would like to check the evaporator, but it seems like a huge hassel to remove. Is there an easy way I can just see it to shine the UV light on it? Myabe under the dash? I know the heater core is there, is the evaporator right behind it?

 

it is not.

ID buy a replacement from a 4th gen that is for 134a and swap it in.
No need to mess around with an old r12 unit.

 

It is not. Comes RIGHT out.

3 bolts in the interior, just under the edge of the carpet; 4 IIRC on the engine side, mostly across the top and toward the engine. All 13mm IIRC butt a couple might be 10.

I recall needing an evap housing once. Junkyard closed at 5. I got there at 4:55, went out and found a car, and was standing at the counter with one before they shut down at 5. I defecate you not.

 

Not only is that evaporator not a direct swap, the evaporator design does not need to be changed. The evaporator could care less what gas is evaporating in it as long as the boiling point is around freezing and does not dip below freezing the surface constantly. R134a era evaporators will have metric fittings or in the case of a 4th gen bolt on o'ring seal.

The condenser is what needs to be changed with a R134a conversion to restore proper cooling. Install the largest parallel flow that can fit.

 

I remember most older GMs being about like that when they had underhood suitcases for evaporator housings. My memory might be off but IIRC they are a weird size bolt head. 5/32 or maybe 7/32. 10mm just seems way larger than I remember.

I put an evaporator core in both a Camaro and Transam over the years.

 

I will also add you can pickup a functional refrigerant sniffer that works very well for under $100. Just be warned they pickup hydrocarbons from the exhaust or evaporating ac flush too. Figured that out using one the other day to locate a small leak in a 2003 Avalanche which was as I assumed the high side service port. The sniffer figured out that truck has an exhaust leak from a broken manifold bolt that you can not even hear. It is a LS, go figure they all break manifold bolts and always the ones up against and burried under the firewall.

 

I wuld think you can pop off the 7?? mm bolts and I think 10mm bolts that hold the top of the evaporator case on, pry it gently open and shine the light in there