Nothing wrong with your Yellow Jacket test kit, or a digital unit like the one I linked to. Both require the same type of connection to the LP system, one just displays the pressure in an analog/mechanical fashion, the other displays it digitally/electronically.
Both types of gauges would need to be calibrated periodically, or at least checked against a real water column manometer to ensure its accuracy. That’s probably why a lot of guys prefer to simply make one out of clear tubing and a ruler. Unless your ruler shrinks or grows, or you use one of those fisherman’s rulers that always measure long, there’s no calibration needed.
The Yellow Jacket kits I’ve seen have always come with a tube nipple to connect the gauge to a test port. Is yours not the right size? Have you located a test port?
Here’s a picture of the backside of my fridge, showing the location of the best test port you should use when checking the LP pressure to the fridge burner. Unfortunately, that plug on mine is stuck and I couldn’t get it out. There are a couple of other test ports on my camper. My regulator at the LP tanks has a test port, so I used that one instead.
There are a lot of little things that can cause an absorption fridge to not perform well, and low LP pressure is one of them. If your fridge works well on AC, and poorly on LP, you have an LP problem, not a cooling unit problem.
The statement that they are coolers is totally false. If they are working right, you should see it maintain around 0-10 degrees in the freezer, and 35 degrees in the fridge section. In fact, these are the temps I typically see on my fridge. The fridge probe is right under the cooling fins. This was when I was in Phoenix last year, and the outside temp was over 100, and inside the camper was about 78.
:):)
