Where is the expansion valve located on a 90 honda accord? Also, does anyone have a diagram?

 

Expansion valve is attached to the evaporator under the dash. To access, you must discharge the system and disconnect both tubing connections on engine side of firewall, then remove the evaporator box from under the dash, after removing the glove box for access. Don't try removal w/o an Accord Shop Manual. Suggest downloading the 91 Accord Manual from hondahookup.com. See Online Manuals link under DIY.

Job is really pretty easy, especially compared to many US models which require dashboard removal to access the evaporator box. Replace all the orings on the expansion valve and temperature sensing bulb. They tend to dry out and leak, especially at the brass/aluminum joints. Lube w/ Nylog or other oring lubricant.

Probably a good time to replace all orings in the AC system connections, and install a new receiver/drier before vacuuming and recharging. You don't want any precious R12 to leak for a long time.

good luck