I'm looking to buy a used popup that has A/C. I've seen a number of nice popups that don't have A/C, but are prewired for one.
If a popup is pre-wired for A/C, how much work is involved in installing a roof-top unit?
In my opinion, if you are thinking about buying used, it's probably pretty easy to find a PUP with an A/C already installed. Of course, that is if you buy from someone that lives in a part of our beautiful country that lends a warm summer. I'm not well versed on the procedures of cutting the space and mounting (and proper sealing) but if you're looking for A/C, I'd spend some time finding someone that has a used unit with an A/C already installed. My friend just purchased a 1998 Starcraft in excellent condition for use by his family of 5 for $3,000! It has A/C. Just have to be diligent at looking. There are a lot of people out there that think camping is what the wife is going to want to do. Then they store it for awhile until they realize the ultimate... Happy hunting!
If they are pre-wired, that usually means they also have the standard 14x14 roof opening as well, i.e. a crank open vent. RV a/cs are made to fit those openings and are pretty straight-forward to install after removing the existing vent. Instructions will come with the a/c - whether a Coleman or a Dometic (Duotherm). The biggest problem is that hey are heavy - you will need help from a buddy.
Sealing is not a big deal. There is a gasket that goes underneath the outer section, around the 14x14 roof opening and you merely tighten down a set of four bolts that clamp the inner and outer sections together against the gasket.
Or at least, that's the theory of it. I haven't ever instaled one from scratch myself.
I'm currently looking into doing the same and for the most part, it looks like it will be an easy task. One thing I wanted to add, however is that you may have to check to see that the breaker dedicated to the AC is hooked up. The reason I say this is that I was taking apart the crank-type roof vent in my unit for cleaning and I noticed that the romex for the pre-wired AC in the roof was terminated by just cutting it. There was an 18 inch length of cable that was wrapped around the roof vent trim but there were no wire nuts or any other special connectors used to terminate the wires. This made me wonder if there was any voltage present so I made sure the breaker dedicated to the AC was in the on position and checked for voltage and there was none which was good because it would have been a fire hazard in its present condition. I haven't unscrewed the breaker panel but I would guess that they (purposefully) left the breaker disconnected and it should be a simple manner to hook it up when installing the AC.
I have done the install, and it was pretty easy. Heed the previous quote, that it is heavy. I did manage the entire operation singlehanded, However, I wouldn't repeat it. I just got in a situation where it was my only option.
The 14x14 hole is all you need. The trick with pre-wired is whether the wiring has a conduit to the opening. Mine did not, so I had to drill one in. Not hard, just added 10 minutes to the job.
As has been mentioned, no holes, just slides in, bottom attaches and it acts like a clamp. Way easier to put one in that to change a vent. Just be sure to clean old sealer off as best as you can.
With a pop up even the weight is not as much of an issue, the roof isn't that high. On mine I had to lift it, then step up onto the side rail of my pickup, then push uip and over. Again, not a task I would repeat.