DIY: A/C Insulation

[LugNut]

I too did this modification, a couple of months ago, in response to the very weak AC performance. Thanks for the idea!



I did the entire suction line, from the firewall to the compressor. I mostly used insulation for 1/2 in. copper tubing (one stick, from Home Depot), but also a little for 3/4 in. on some bigger sections. For even bigger parts, like the in-line accumulator, I had to wrap with two split pieces.

There's definitely more cooling capacity, but at the cost of fuel economy. Before I could barely detect a difference in lugging of the engine with the compressor engaged. But now there's a big AC load on the engine.

On warm days I now get 40F air, but today, at 105F outside, I only got 52F. And still definitely not enough total cooling capacity even though the supply air is much cooler than before. But much better than no AC at all!

In response to some questions/concerns by prior posters, yes, there should be insulation on this line (but do at your own risk). My RAV4 does have some factory-installed insulation for part of the run. And if you have a split-system AC at your house/apartment, look at its large line ("suction"/"vapor") -- it hopefully still has its black foam insulation. But the small line ("pressure"/"liquid") definitely should not have insulation -- the refrigerant is still very hot coming out of the condenser, so losing more heat on its way to the expansion valve is a good thing.

Also, yes there is danger in doing this mod. First, lots of sharp edges, etc. under the hood! But there's also a danger that if the system is overcharged, or the AC is operated when too cold outside, that "liquid" refrigerant could enter the compressor and damage/destroy it. The accumulator is there to help prevent this, and I almost left it uninsulated. But I've done AC work, so repairing a system isn't that scary to me, and this insulation mod was intriguing. Glad I did it, so far. You, though, might want to have your refrigerant pressures checked immediately after doing this mod.