Mechanic dropped a few pounds of freon and die into the system and we can not find a leak anywhere in the engine compartment no sign of the die at all. Mechanic is a toyota guy but feels it may be under the dash. Any ideas of what this might be and what it should cost?

 

Are you losing freon?

 

Flourescent dye??
You might be able to use the flourescent light to look up the evap drain tube for signs of leaks, or oily seepage. The freon bonds with the oil and the dye mixes with the oil.
I have also had to drop out the glove box and remove as many clips as possible from the evap case, then wedge the case open enough to shine the light thru to look for dye traces around the expansion valve area.
Also pull the connector off the pressure switch and look in there for oil/dye, that is a common place for leaks.

 

okay really stupid question where is the connector valve?

 

I've experienced leaks due to age in the expansion valve connections to the evaporator on two Accords (90EX and 94EX), and shaft seal leakage on the 94EX. The expansion valve is brass and connects to an aluminum evaporator. Dissimilar metals corrosion causes a white powder to form at the connections. This powder eventually distorts the oring and a slow leak develops. Evaporator must be pulled to repair the connections w/ cleaning, polishing (soft steel wool) and new orings.

Good news is pulling the evaporator is not too bad a job in the Accords. Get a shop manual from the Online Manuals links in DIY section and you're ready to repair. I would also replace all orings in connections, any hoses that looks suspicious, new receiver/drier, and new compressor shaft seal, if there's any indication of leaks (dirt ring around clutch assy).

good luck

 

I still can not find the location of the pressure switch, is it under the battery tray?

 

On 90 Accord, for which I have manual, the pressure switch is right up high on the driver's side. The high side pressure hookup is only a few inches away.

You need a manual of some type. Try to download a 90-93 manual from Online Manuals DIY forum of this site.

good luck