The deal - typical reach in sandwich station at typical pizza shop. Cap tube R134A. Unit has new evap (cap tube NOT replaced). Unit erratic temps, would occasionally rise for no reason, then drop back down to normal temps. One of those nuisance calls. Half of our tech force has been out on this unit and EVERY SINGLE TIME the unit was working on arrival. Next day he calls, its warm again, but by the time we get there, everything is ok. He says the only thing he does SOMETIMES is shut the unit off and turn it back on and it seems to work fine, but most times it just seems to come back down on its own.
I get the call and of course its working when I get there. No gauges hooked up - nice cool compressor, plenty of refrigeration back to compressor, fair amount of heat coming off condenser - condenser was power washed by last tech. Decide to hang around and have lunch, clean out my van, anything to kill a few hours. Sure enough, temps start to rise - feel compressor, getting hot, suction line now warm and condenser cool - hook up LOW SIDE ONLY and unit is in a vacuum? Watch it for a few more minutes, goes from 10" vacuum to 5psi, drops down again....so I shut off unit (like customer says he does when unit acts up). Wait a few minutes, suction pressure balances (again, no hi side on), turn on and voila, unit back to normal. Condemn cap tube and will return to change.
1. Did I make mistake not hooking up high side? With something this obvious, I assume restriction floating around.
2. One of the techs told me he put dye in the system. I'm unsure if dye would cause problems in a cap tube system - have never used it in a small system.
3. Anyone ever see anything like this? I don't work on cap tubes often, but when I have they are plugged, the unit is down and it jumps right out at you. The fluctuation of the suction line pressure is what has me scratching my head.