Guys,

I've got a 1991 with R12 freon. Great when it's cold.. but it's low and I can see the sealing o-ring on the lower pressure switch on the expansion valve is torn.

What o-ring is suppose to be on the switch? maybe it was done wrong by me last time.

I was thinking of possibly converting and changing to a high and low pressure switch. I think those are common on later stuff. Then you still have the low pressure cutout and the high pressure switch can run a relay for a fan to prevent extremely high pressures in low speed traffic before the engine is up to temp.

Michael

 

I would stay with the expansion valve as they are almost maintenance free, in the newer systems they do use a lo and hi press cutouts but they also have a "fixed orifice tube" which is what meters the freon instead of the expansion valve. The fixed orifice is not serviceable or replaceable as it's incorporated into a system line and they can become restricted or blocked easily requiring line replacement. Just convert what you have to 134a or something of your choosing. If you want better cooling close off the heater core supply during AC operation and you could also install a relay activated condenser fan that would come on with the AC compressor.