Cruisair Charging

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I have a bedroom Cruisair unit that isn’t performing as well as the other two. I’ve made sure the condensing coil and evaporator are clean, but this unit isn’t producing any condensation water from the drain tube, whereas the other two discharge water almost constantly due to the GA humidity.

I hooked up the gauges and added freon slowly until the sight glass cleared and all foam was gone. The Cruisair manual has charts to help identify the correct charge, but I’m not reaching the recommended numbers. The manual states to add freon until the sight glass is clear.

My issue is that the high side pressure only reaches 105 psi when it should be around 210 psi, and the low side is at 60 psi when it should be closer to 70 psi. Jack mentioned he got around 45 degrees at the suction line, but I’m getting 65 degrees.

Here are the room air temps with the outdoor air temperature at 82 degrees:

• A/C air temp at the vent: 69.3°F
• Air intake (return): 74.7°F
• Room temp: 76.5°F

So, my question is: how do you determine the correct amount of freon to add without overcharging? I suspect the unit is low on freon, and adding more might bring the numbers closer to the manual’s recommendations.

[MyPrevost]

Hi Tom,

You might want to reach out to AAP in Milford, VA at 804-633-9454. Fred, Johnny, and Bill are the key contacts there. You could have a leak in the system. These systems are designed to shut down under high pressure if the freon is overcharged.

Getting the best performance from my system has been a mix of science and art (and a bit of luck). I’m also having issues with my bedroom unit.

Best,
Jim

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I had trouble with my galley Cruisair holding a charge a couple of months ago. One thing I learned from both Prevost and Johnny at AAP is that the cost of rebuilt and new Cruisair units has skyrocketed.

In my case, it turned out the issue was a leaking hot gas bypass valve. It was quite difficult to detect, but the Prevost tech did an excellent job of tracking it down, cutting it out, and sweating in a new one. I haven’t had any problems since.

 

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Truk,

You’re not quite there yet. Keep adding freon until the suction side feels “beer cold,” then use an IR gun to measure the temperature. Slowly add freon until you reach the lowest temperature. If you go past the optimal temperature and have the high side hooked up, you can reduce the charge by briefly opening the high side valve to let some freon escape back into the jug.

At 65 degrees, it will take more freon than you might expect, and there should be bubbles in the sight glass when you’re finished.

[MyPrevost]

truk call me rick 813-833-2284 there’s a couple things that could be wrong

[MyPrevost]

Jack,

The manual is very specific about the sight glass not having any bubbles, but Johnny at AAP mentioned that the sight glass should have bubbles. It seems like the newer units might be different from the old ones. Thanks for the advice—I’ll give it a try. I also remember Lester mentioning at POG 1 that it needed to be “Beer Cold 30”!

Rick, I’ll be calling you soon.

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You are right, I think that it all changed about 1996,let us know how you fixed it.

[MyPrevost]

What’s the ideal IR reading for the suction side? I’m currently reading 42°F on one unit, and 43°F and 40°F on the others. Should I aim for the low 30s? I’m aware that the reading can vary depending on where you point the IR gun—I’m currently shooting the fitting where the line connects, which also has the Schrader valve.

We’re planning to adjust these on Monday, so any specific temperature target would be helpful. It was around 85°F inside the building this morning when I took these readings.

Thanks!

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I went down to Steve Bennett’s today and checked out his system. We saw different numbers, but his unit still produced very cold air. It seems like this might be one of those situations where it’s a bit of a guessing game to get it just right.

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Kevin,

I use a rubber band to secure the trigger on the IR gun and then wedge the gun into position near the Schrader valve. This helps keep the IR gun steady and prevents it from moving. Your temperatures look quite good. If it were to get into the low 30s, it might risk freezing.

 

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Thanks Jack, good idea to hold the gun in one spot. I will see if I can get mid to high 30’s!

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Jack,

I had to pause the work because we took a trip to the Smoky Mountains, but I’ll be back on mine this week. I was only getting 65°F at the suction side near the Schrader valve with the IR gun. I plan to call Rick as he suggested to figure out why the high side pressure is only at 105 psi. I’m hoping that being undercharged is the issue.

Kevin might get his down to 36°F while polishing the fittings!

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I guess I should stop, already polished!

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