j.kenzie@sbcglobal.net

Hi,
Like the title says, I am refurbing my a/c system. I am changing the expansion valve, and I have never seen it done before, but would it work better if it was insulted from the engine compartment heat? It has a sensing bulb on the side of that big aluminum block, which seems to be sticking out into the warm region of the engine bay.
Thanks.
Dave

dprantl

There are some cars that have a special "box cover" for the expansion valve that is lined with insulation. It couldn't hurt, but probably won't help that much. I would just leave it as it is.

Dan
'91 928GT S/C 475hp/460lb.ft

dr bob

The "sensing bulb" is reading the return line temp and adjusting the inlet flow to maintain the correct return temp based on the heat added from the car. It's not particularly sensitive to ambient conditions. It sits in the well aft of the firewall so it doesn't see direct engine bay heat. Those lines and the valve are often insulated in non-automotive systems to cut down on condensation and subsequent dripping, but it's not usually an issue in these cars. So bottom line is that it's OK to insulate. Better would be shielding the steel plumbing in the engine bay, particularly where it passes the engine exhaust on the passenger side above the frame rail on the fender wall. Besides the radiant heat from the exhaust there, the refrigerant lines run with the coolant lines. So shield from engine heat, insulate from coolant lines, with something that will stand the abuse from the heat and wrenching.