Dash Air Recharge

[Dick Simonis]

Thanks Gerald.  I'm going to have it looked at by a shop in Idaho Falls but he advised me that the parts might not be readily available from local sources.

I am curious though about this trinary valve. Way back when the R-12 systems always had separate high and low pressure switches.  How can one switch monitor both the high and low side??  In which line is it installed?  Thanks for any enlightenment.


Dick

[Gerald Farris]

Dick,
I replaced the expansion valve and the dryer on my coach last year and Fleet Pride truck parts in Phoenix had both of them in stock. They were fairly common truck parts.

The trinary switch is in the high side at or near the dryer. It does not monitor the high and low side, but it monitors the high and low pressure ranges in the liquid line (high pressure line after the condenser). It prevents the compressor from engaging if the high side pressure is too low (discharged system) to prevent compressor damage, and it turns on the condenser fan when the pressure rises sufficiently to cool the high pressure gas so it will condense into a high pressure liquid for the expansion valve. 

Gerald