Hi, we have a 1986 Monitor TT that came new with a Dometic SL135RB roof top AC unit. We bought the TT about 7 years ago and the AC has always worked alright - just alright, never stellar, but reasonably decent giving its age. Over the past July 4th weekend it was very hot and extremely humid and it eventually quit cooling as far as I could tell. Question: Should I attempt to give it a charge of refrigerant? What type of refrigerant might this unit use. The original owners and installation manuals do not have any details on the refrigerant type. I have a gauge and tool to fill R134a systems on my vehicles but I am not sure if this would work if the old AC unit is an R12 system. Not sure if R12 is even available anywhere.

Thanks for your thoughts.
-Deon

The age of your TT and AC would be easier to change to a newer AC unit and will make it much cooler for you.
Try this LINK for a new one the 14" opening should be ok for new ones.

Sounds like the cooling unit is shot. It is not cost effective to mess with it. Buy a new one and get a new warranty and be back to being cool. I have not heard of much success of tapping and recharging, and if it does on one under warranty you just voided it.

After 27 years I'd think everything is pretty well used up. Buying a new unit is the better option. You will spend near $100 for a A/C technician to recharge you ole unit, and around $600 for a new one with a 3 year warranty, that's 18% invested in the old one that may experience compressor failure tomorrow.

any chance it was turned down to low and froze up. chevman