AC Clutch not engaging

[mnathan]

Hello all,

Recently my AC stopped blowing out cold air. Here are some notes about the issue.

-Hot air works fine, when set to cold it just blows tepid
-AC light does turn on when pressed
-AC Clutch does not engage when AC set to 60f full fan speed.
-With car off I can spin the clutch manually
-edit: AC Fuse appeared undamaged. Thanks EDBWOY
-edit: Blend door functioning

This is my first time doing any AC work. Any tips on how to go about fixing this? I have plenty of tools but no know-how. I have heard that those AC recharge cans are useless. Unfortunately today is Christmas day, so I am unable to go purchase a pressure gauge for the refrigerant lines.

[VStar650CL]

There are a whole raft of things which can cause the compressor to not engage. The ECM will prevent it if the refrigerant pressure is low or the pressure sensor is bad, the HVAC brain will prevent it if any of the temperature sensors (cabin, evap, ambient) reads cold, and the BCM will prevent it if the blower feedback shows the blower isn't working. The clutch is actually driven by the IPDM, which is located next to the battery on an M. You can test the clutch circuit by using the IPDM Auto Active Test, described on page PG-22 here:
https://www.nicoclub.com/service-manual ... 8%2FPG.pdf

If the clutch clicks during the AAT then it's probably healthy and your problem is something else upstream. If so, first thing to try is adding about half a pound of refrigerant and see if the system will kick on. If it does, the system may just have bled down over years or you might have a leak. Get a UV dye kit, add some dye, and run it a bit. If the UV flashlight and glasses don't show any yellow splotches then you probably just need an evac and recharge. A/C systems do lose refrigerant over time just like a tire loses air, refrigerant molecules are simply much larger than air molecules and leach out much more slowly. If half a pound doesn't wake it up then things get complicated, you probably have a bad sensor somewhere.

[mnathan]

AAT completed. I can hear a click and see it move a very small amount.

Imgur link with sound: https://imgur.com/a/xkZY3I3

I will buy a kit and add some refrigerant tomorrow when the stores open. I suppose I can kill two birds with one stone by adding some UV. That AAT test was neat. Revealed to me that I only have one fog light and one license plate light.

Thanks!

[VStar650CL]

[mnathan]

I feel it may be crucial to include that my radiator/fan assembly mounting hardware broke at one point, leading to the radiator and fan to drag lightly on the ground. I remounted it with zip ties about a year ago.

When I look for leaks with UV tomorrow that will certainly be a suspect area. The condenser should be mounted directly to that and probably has moved a lot more than the average condenser.

[VStar650CL]

Yep, you may well have developed a fatigue crack in the condenser plumbing. That's pretty common when a radiator support is damaged and not repaired properly. Definitely worth looking at.

[mnathan]

I found that I can loan manifold gauges and a vacuum pump from Orilies. Hoping this local branch has it so I can add some R134a following ChrisFix's guidance. Found a can that has a UV dye additive but no stop leak, which seems ideal.

I've heard an AC leak can take some time to show with UV so hopefully this 300 mile drive will get it flowing. Oddly enough I will also be adding dye to my oil for a very bad leak (1.5qt/1000mi), so hopefully the dyes show up as different colors.

This may be the price to pay for zip-tying a radiator on. Lesson learned

[VStar650CL]

If the problem is cracked plumbing then it will show up pretty quick. Stuff like flattened o-rings can take a lot longer, but all the most common stuff -- fractured pipes, abraded hoses, bad compressor seals, road-damaged condensers -- will all show up quickly. You may already have dye in the system, take a look at the label on the bottom of the engine hood. If it's green, that means dye was added at the factory.

[mnathan]

You are right, the label detailing the type and mass of refrigerant is green and asks for "Nissan UV Luminous Oil Type S".

This means I can check for the leaked UV material before adding dye to my oil, which is convenient.

I am mainly hoping that if the system has leaked, that it is already entirely empty. If there is any remaining R134 I wouldn't have the ability to purge or store it correctly. I would hate to go to a shop but I don't think there is an alternative for that type of thing.